Re: Topband: B7P

[John Kaufmann via Topband]

It is also my experience that stations in China and Southeast Asia in general 
do not hear well at all on the low bands.  One exception is BG2AUE.  I have 
worked him multiple times on 80m CW from my QTH in the Boston area. He hears 
extremely well on 80.  Every single time I've worked him there, he's been very 
weak but he's always answered me immediately.  I've also seen him spotted a few 
times on 160 but have yet to hear him there.  That's an extremely difficult 
path from W1 on 160.  In fact, zone 24 is one of the two remaining zones I need 
for 160 WAZ, the other zone being 26.

73, John W1FV


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Re: Topband: 9M2AX finally after 15 years

[John Kaufmann via Topband]

Congratulations Steve for this epic contact!  As already pointed out, much of 
the difficulty is the very high level of QRN on Ross's end.  He gets almost 
daily thunderstorms.  My experience coincides with what Dave, W0FLS, said.  The 
most favorable conditions to work 9M2AX are around the equinoxes.  Ross has 
said his noise level is lowest then.  

After 20 years of chasing Ross, I finally worked him right around our spring 
equinox on March 23, 2007.  From here in W1, the path is a skewed path to the 
SE, and that path seems to exist (sporadically) only during low sunspot years.  
At best, it's a very marginal and difficult path.  I had been hearing 9M2AX 
throughout that month just after my sunset but he was never able to pull me 
through.  Finally we got enhanced propagation on March 23 just a few minutes 
after my sunset and a few minutes before his sunrise.  There were signal bursts 
almost like meteor scatter pings.  We were able to exchange callsigns and 
signal reports before he quickly disappeared.  I continued to hear Ross until 
the first week in April, after which we no longer had any common darkness.

It's good to hear that Ross is active again after several years off the low 
bands.  It takes a lot of persistence on his end to listen to QRNNN every day 
and make only an occasional contact.

73, John W1FV

-Original Message-
From: Topband  On 
Behalf Of David Raymond
Sent: Monday, February 12, 2024 4:01 PM
To: topband@contesting.com
Subject: Re: Topband: 9M2AX finally after 15 years

Congratulations Steve!  I've learned over the years that the best time to work 
Ross, at least from here in the Midwest (Iowa), is within a month or so of 
either fall or spring equinoxes.   Ross has always been a reliable, persistent 
operator and works hard to pull calls through his QRN.

73. . .Dave, W0FLS

On 2/12/2024 1:28 PM, ve...@shaw.ca wrote:
> For at least 15 years (perhaps more) I have been chasing Ross 9M2AX for a new 
> one on 160m.
> For some reason, a QSO has eluded us.
>
> >From VE6 Ross is 13,000km at 320 degrees AZ, and the path is usually skewed 
> >southward.
> Every morning this winter season I have been at the radio RX for Ross, but in 
> spite of fair-good reports from ops down south in AZ and CA, I have never 
> copied him.
>
> For some reason, this morning his signal peaked up just before my sunrise.
> My tower was cranked down, so I had to wait for it to get to full height and 
> the amp to warm up.
>
> After many calls and a few QRZ? Ross gave a 6 ?.  A few more calls and he had 
> my call, but gave me a VE6WZ ?? without a report.
> I responded with ONLY his report and made sure NOT to send my call again.  I 
> was getting quite concerned that I might lose the contact after I sent my 
> report many times.
> Finally, Ross came back with a 339 and we completed the QSO.
> Our QSO was at 1452z, 10min before my sunrise at 1502z.
>
> Ross struggles with very high QRN in 9M2 so I am very grateful he was able to 
> pull me out.
> Because I have waited so many years for this QSO, I wanted it to be as "pure" 
> as possible, so I avoided any packet cluster "hints" that I was calling, and 
> I did not acknowledge I was even QRV in the KST chat room.
>
> I must say that Ross is a true QRN-warrior to persevere through what must be 
> painful RX conditions!
>
> I was TX with the 2 el Parasitic array, and listening in diversity.
>
> Here is a recording of our QSO.  If you listen, you will understand why I was 
> quite worried I was going to lose the QSO.
> This morning his signal seemed almost equal on the direct path, and the skew 
> west path.
> In the left ear is the west 4 element BSEF Beverage (BOG) array, and the 
> right ear is the Asia 2 el Beverage (BOG) broadside phased pair.
> (the clicking is poor internet packet dropouts on my connection to my 
> remote 100km north of my home)
>
> https://drive.google.com/file/d/1ot1RhA1Gim1VoHEw6u0QA3T7QShf9bCE/view
> ?usp=sharing
>
> 73, de steve, ve6wz
> https://www.youtube.com/@ve6wz/videos
>
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband 
> Reflector

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Re: Topband: NCC-2 antenna pattern?

[John Kaufmann via Topband]

If you are going to use the NCC-2 to null a nearby in-band transmitter, I think 
it's very likely that the NCC-2 will get overloaded by the extremely strong RF 
and not be usable.  I've tried this before and found that to be the case.  In 
fact, I designed my own totally passive nuller to get around this problem.  It 
worked and was able to create very deep nulls on an in-band transmitter, but 
turned out to be very impractical because it required constant adjustment to 
maintain a null as antennas were changed or rotated.  

The other thing to consider is that if the interference is coming from the same 
direction as a signal you want to hear, nulling the interference will also null 
the signal. Nulling works best when the interference comes from a very 
different direction than the signal.  It also helps greatly if the interference 
sensing antenna receives the interference much more strongly than the main 
antenna.  This can be done by placing the sensing antenna close to the 
interference source, if that's possible.

73, John W1FV

-Original Message-
From: Topband  On 
Behalf Of Kenny Silverman
Sent: Saturday, December 16, 2023 10:05 PM
To: Rick Kunath 
Cc: topband 
Subject: Re: Topband: NCC-2 antenna pattern?

Rick, my application is for an in-band RX antenna, but on a higher band. I just 
thought the guys here might know more about the NCC-2, MFJ or QRM eliminator 
than most others. 

One thought was to create a 2 ele phased vertical array for the RX antenna with 
a known pattern and put the null towards the TX array, along with physical 
separation to allow in-band receiving. 

But I was thinking an adjustable phasing system may produce a better null. But 
I wouldn’t want the adjustable unit to create a clover leaf pattern for 
example. One null might take out the interference but another null towards the 
desired receiving direction might be created and is not desired. 

I hope I’m explaining this well. 

Regards , Kenny K2KW 

> On Dec 16, 2023, at 9:47 PM, Rick Kunath  wrote:
> 
> What's your application Kenny and what would you be feeding the antenna 
> output of the phaser into?
> 
> Rick Kunath, K9AO
> 

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Re: Topband: ZD9W

[John Kaufmann via Topband]

I heard them a couple nights ago on 160 CW, around 2330Z, roughly an hour
after local sunset in W1.  They were actually quite strong on peaks but
there was deep QSB that took them down to almost nothing.  They seemed to be
having trouble hearing.  I heard them come back to N1DG but all the other
stations they worked were Europeans.

73, John W1FV

-Original Message-
From: Topband  On
Behalf Of Craig Clark
Sent: Monday, October 9, 2023 12:29 PM
To: topband@contesting.com
Subject: Topband: ZD9W

Looking at DX Summit it looks like FT* will be his preferred mode of
operation. 
Not on digital. Any information on possible CW operation? 


Craig Clark
K1QX
603-520-6577 cell
603-899-6103 home
Sent from my iPad
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Re: Topband: High Impedance RX Antennas

[John Kaufmann via Topband]

Another tool I've found indispensable for setting up and troubleshooting phased 
vertical RX arrays is a two-port VNA.   I use an Array Solutions VNA-2180 (now 
discontinued) for critical measurements.  I also have a NanoVNA H4 
(https://nanovna.com/) which is a very "affordable" VNA that can be used as a 
portable, handheld, standalone instrument and that you can take out in the 
field.  In most cases, the NanoVNA H4 is more than good enough.

There is a learning curve to using a VNA.  However, once you learn it, you'll 
be able to make very accurate measurements of delay line lengths, preamplifier 
gain and phase, phase combiner gain and phase.  Most VNA's also have a TDR 
function, although it is usually based on frequency domain measurements that 
are transformed to the time domain.

I'm running a homebrew RX array and it would have been almost impossible to get 
it running as well as it is now without a VNA.

73, John W1FV
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Re: Topband: 1940 kHz Intruder

[John Kaufmann via Topband]

Here in the Greater Boston area, the signal peaks from the southwest on my 
8-circle array.  It's not real strong, varying between S4 and S6.  I can tell 
there is some audio in there but it's not strong enough to identify.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of David Olean
Sent: Wednesday, January 4, 2023 7:09 PM
To: Frank W3LPL; topband
Subject: Re: Topband: 1940 kHz Intruder

I listened this evening at 2345 UT Jan 4, and hear the best strength 
with a southwest beverage. I live in Southern Maine. Signal was about S9 
and sounded distorted with possibly two station audio streams.  I hope 
this helps. My beverages were really messed up (destroyed is more like 
it) from the last cyclone around christmas. My EU and East wires are 
dead at the moment. I have all the others working again.

Dave K1WHS

On 1/3/2023 5:56 PM, Frank W3LPL wrote:
> The 1940 kHz broadcast station is audible now (2245Z Tuesday)
> Its roughly northeast of Maryland, perhaps in New England
>
> I did not hear it yesterday
>
> 73
> Frank
> W3LPL
> _
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Re: Topband: [RFI] Powerline noise question

[John Kaufmann via Topband]

The WD8DSB mini-flag truly is a fantastic RFI-hunting tool.  When I saw the 
original article in QST, I recognized immediately that this was a great 
"invention" by WD8DSB.  Like many of you, I deal with quite a bit of man-made 
RFI on 160m, so I bought one of the very first ones sold by DX Engineering.  Of 
course, it's not hard to build your own from the QST article.  The antenna is 
very broadband and works from the medium wave bands up to at least 50 MHz.  
Having a unidirectional pattern with a sharp null off the back is a huge 
advantage over conventional bidirectional DF loops.  You can narrow down 
direction of signal arrival unambiguously to within a few degrees.
As W3LPL says, it is a very low gain antenna that does need a very good preamp 
behind it.  You need a preamp with not only a lot of gain but also a very good 
noise figure because ultimately the sensitivity for hunting weak signals is 
limited by noise.  I have the companion preamp that DX Engineering sells for 
this antenna.  Its noise figure is about 4 to 5 dB, which is quite good for a 
reasonably priced, battery-powered preamp that you can carry around with you.  
By way of comparison, I also have a homebrew high gain (35 dB) preamp, made 
with MMIC's, with a noise figure of 2 dB, which is very close to the best you 
can do for HF.  However, most of the time I use the DX Engineering preamp 
because it is good enough for all but the weakest signals.
Bottom line is that the WD8DSB mini-flag and a portable receiver are all you 
need for tracking down noise sources.  As one more auxiliary tool, I sometimes 
use the tinySA Ultra (an improved version of the original tinySA hand-portable 
spectrum analyzer) to look at the spectral signature of a suspected source in 
the field to confirm it's the same source that I'm seeing at my station.  See 
tinysa.org/wiki/ for more information.
Disclaimers:  I have no affiliation or commercial interest in DX Engineering or 
the tinySA product.
73, John W1FV


-Original Message-
From: Frank W3LPL 
To: Richard 
Cc: rfi ; PVRC ; topband 

Sent: Fri, Dec 30, 2022 8:09 pm
Subject: Re: Topband: [RFI] Powerline noise question

Rick,

You'll be very pleased with the performance of the WB8DSB RFI hunting
flag antenna.  

Don't forget to need lots of preamp gain. The WB8DSB flag is about 60 dB
down from a dipole on 160 meters. 40 dB of preamp gain is needed until
you're very close to the RFI source.

73
Frank
W3LPL

- Original Message -
From: "Richard" 
To: "Frank W3LPL" , "rfi" , "PVRC" 
, "topband" 
Sent: Friday, December 30, 2022 8:25:47 PM
Subject: Re: [RFI] Powerline noise question

Thanks Frank.  You got me unstuck.
I have ordered the DX Engineering Kits and the PL330 receiver.

73
Rick N6RK


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Re: Topband: My new 9 Circle works great!

[John Kaufmann via Topband]

Here is additional information on the 9-circle low-band receiving array.  It
was originally designed for operation on both 160 and 80 meters.

It was based on a couple articles I wrote for NCJ in the September/October
and November/December issues in 2011.  The design was turned into a set of
electronics kits that were produced and sold by DX Engineering in
collaboration with the Yankee Clipper Contest Club (YCCC) and myself.
There were a few changes made in the DX Engineering implementation relative
to the NCJ design, the most significant being a reduction in the circle
diameter from 140 to 120 feet.  This reduction had negligible effect on 160m
but it improved the 80m performance and also allowed the array to produce
"usable" performance on 40m.  

The DX Engineering kits eventually sold out and were discontinued after
that.  However, there are still a few direction switch box kits left over
that you can order from DX Engineering:
https://www.dxengineering.com/parts/dxe-yccc-switch.  You can also download
a copy of the system user's manual from DX Engineering:
https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.
pdf.   The manual has a lot of technical information about the system,
including circuit diagrams and beam pattern calculations, as well as
assembly instructions for the DX Engineering kits.

More recently, PI4CC has produced 9-circle PCB's that you learn about here:
https://www.pi4cc.nl/tech-info/rx-array/.  VE6WZ also created his own
version of the PCB's and he will share the info with you, or he may chime in
here.  You can learn more about the VE6WZ system on his qrz.com page.

Disclaimer:  I have no commercial interest in or affiliation with any of the
sources of electronics mentioned above.

73, John W1FV


-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Joe
Sent: Monday, December 5, 2022 2:16 PM
To: topband@contesting.com
Subject: Re: Topband: My new 9 Circle works great!

Any links to this system?

Joe WB9SBD

On 12/4/2022 1:34 PM, Jim Miller wrote:
> Thanks to Steve's, VE6WZ, excellent YouTube videos, I decided to tackle a
> better RX antenna. I've been using a 2 element array phased by an NCC-2
> which is better than what I've had in the past (BOG, K9AY) but I wanted
> better.
>
> After evaluating my space available and finding it too small I asked my
> neighbor for seasonal use of their adjoining lot and they graciously
> agreed! My N, NW and W elements are on their property.
>
> Steve's videos include KiCad files for the combiner and preamps and he was
> very helpful by email with any of my questions.
>
> I just completed the array last night and got it on the air and I was
> astonished by how well it worked.
>
> Of course it isn't going to create signals out of thin air but it is much
> quieter due to better RDF and the front to back is very impressive. Strong
> signals on the waterfall just disappear when the antenna is reversed!
>
> I'm very happy to get such an improved antenna for 80 and 160 in a 120ft
> diameter circle!
>
> As a bonus I use it with PSTRotator and a USB controlled relay box so no
> manual switch box is required on my desk. Just a mouse click selects the
> desired direction or it can track my logger automatically.
>
> FYI, most of the cost is in the aluminum, the combiner and preamps were
> pretty cheap to build.
>
> Many thanks to VE6WZ!!
>
> 73
>
> jim ab3cv
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Re: Topband: Non-amateur stations in Europe on 1860 and 1900 kHz

[John Kaufmann via Topband]

> So how is the QRN doing over there now? Any likelihood of 160m activity
from
> the USA soon?
>
> Roger G3YRO

The QRN on the East Coast is still fairly high most evenings, but there is
propagation to Europe.  OK1CF is on regularly and is usually Q5.  Also a few
G's have been heard recently with decent signals.

73, John W1FV



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Topband: Non-amateur stations in Europe on 1860 and 1900 kHz

[John Kaufmann via Topband]

Some evenings I hear noise-like transmissions, approximately 3 kHz wide,
around 1860 and 1900 kHz that appear to be originating in Europe.  I presume
they are not amateur signals.  On European SDR's they are quite loud and
operating continuously every day.  I find they are actually useful as
propagation indicators into Europe.  They are usually audible when there are
no European amateur signals (CW) to be heard.

 

Do any of you folks in Europe know what these transmissions are?
Transmitter location?  Transmitter power?  Antenna?

 

73, John W1FV

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Re: Topband: Beverage upgrade question

[John Kaufmann via Topband]

Even in a quiet rural location, the limiting noise on 160 will be external 
atmospheric noise.  Improving RDF will generally improve your signal/noise 
ratio against the atmospheric noise.  There are exceptions when there is a 
source of high noise, like thunderstorms, in the same direction as the signals 
you are receiving.  In that case, improving RDF may not help so much.

I have a couple antennas whose RDF's differ by about 4 dB.  That's a pretty 
significant difference.  When I switch back and forth between the two with both 
antennas aimed at the direction of signal arrival, the improvement in S/N with 
the higher RDF antenna is very obvious to my ears, especially when the received 
signals are weak.  From that I would surmise that even a 1 dB difference in RDF 
would be discernable when signals are weak, although the difference won't be 
dramatic.

One thing to keep in mind is that increasing the RDF of an antenna system 
causes an unavoidable narrowing of the beam pattern.  This means the RDF 
advantage is realized only in an increasingly narrow range of angles.  This 
means that the S/N will drop off more sharply for signals off the peak of the 
antenna's main lobe.

73, John W1FV  

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of Kenny Silverman
Sent: Tuesday, August 23, 2022 4:07 PM
To: topband
Subject: Topband: Beverage upgrade question

In a rural area with no significant man made noise, if you redesign a beverage 
for better RDF when do you start to notice a difference?

I’m considering upgrading my single EU beverage at 625’ (190m) to a pair in 
echelon where will each be 550’ (168m) with 20’ (6m)  spacing . The increase in 
RDF is 0.8 dB - will it be noticeable?

I realize if there’s noise in a direction where you reduce the energy you will 
better hear the difference , but my EU beverage is quiet.   Though the F/B 
change will help with thunder storms off the back. 

Overall I tend to receive better than I transmit to EU.  

73 , Kenny K2KW 
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Re: Topband: 8Q7WM Z-22 in VE6

[John Kaufmann via Topband]

I have a low dipole, about 10 feet high, that I use as an alternate receiving 
antenna on 160.  My main receiving antenna is an 8-circle array of short 
verticals.  The vertical array is almost always much better for DX, but once in 
a while the low dipole is better, sometimes dramatically so.  The situations 
that favor the dipole are always the same:  it's at my sunrise and for a period 
of time (15-20 minutes in duration) after sunrise.  If there is any DX 
propagation at all, it usually fades rapidly right at sunrise when listening on 
the verticals.  However, once in a while the DX comes up on the dipole as it 
drops down on the verticals.  It has allowed me to work DX (VK, ZL, JA) after 
sunrise that would otherwise be very difficult or impossible to hear on the 
verticals.

I guess the old adage still holds...you can never have too many antennas on 160 
(as long as they don't interact destructively with each other).

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of VE6WZ_Steve
Sent: Tuesday, March 1, 2022 11:01 AM
To: Robin
Cc: Topband
Subject: Re: Topband: 8Q7WM Z-22 in VE6

Hi Robin…

No I did not RX on anything but the Beverages and 9 C.
However….who knows? Perhaps they might have been better if I had.

This morning Kevin VK6LW was crazy strong, but it seems the 8Q7 boys diid not 
show up.
Let's hope they keep trying that path before they leave.

73, de steve ve6wz

> On Feb 28, 2022, at 10:56 PM, Robin  wrote:
> 
> Hi Steve
> 
> Did you try a high angle receive antenna?  Not so sure on this end, but when 
> we were working skew paths from XZ0A we simply had to have a cloud warmer 
> receive antenna in order to hear anything until a couple hours after local 
> dark. Went several days of near nothing until we put up a dipole at 15 feet, 
> then made something like 30 eastern NA Qs the first night we had that antenna.
> 
> Almost all of the skew contacts we made were reported as arriving from 
> 210-240 for NA east of the Midwest..
> 
> This was during a solar high when the polar oval was strong, so nothing was 
> making it through that area.
> 
> This condition was consistent for several weeks - all the time we were there.
> 
> Quiet environment, diesel powered island hotel, several miles across water to 
> the typical noisy Asian town, and a lot of miles to a big city.
> 
> TX antenna was a full size quarter wave groundplane.  (180 ft antenna fed at 
> 50 ft with dozen radials), so it probably did have a modest high angle signal 
> - a big fat main lobe.
> 
> to this day we have no idea if the RX arrival angle matched the TX departure 
> angle.  The low dipole was not TX grade.
> 
> Robin, WA6CDR
> XZ0A
> 
> 
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Re: Topband: More radials towards EU

[John Kaufmann via Topband]

EZNEC is correct.  Adding more radials, even long ones, in a specific
direction won't preferentially favor the direction in which the radials are
added.  It will help raise the overall efficiency of the antenna to a
degree, depending on how many radials are already in place, but any
improvement will be distributed uniformly over all directions.  

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Ignacy Misztal
Sent: Friday, December 3, 2021 1:16 PM
To: topband@contesting.com
Subject: Topband: More radials towards EU

My shunt fed tower has 36 radials 70 to 100 ft long. Would adding a few
longer radials towards EU help to EU?
 Eznec says no.

Ignacy NO9E
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Re: Topband: Feedline Choke Placement in RX systems

[John Kaufmann via Topband]

In the case of the YCCC 9-circle array, which I designed, common mode 
suppression is deployed at both the antenna ends of the feedlines and at the 
combiner where the antenna feedlines come together.  The YCCC feedpoint preamp 
already includes common mode suppression, so additional feedline chokes should 
not be necessary there.  

 

The reason for additional common mode suppression at the combiner is as 
follows.  The 9-circle system is different than other receiving arrays in that 
there is a center element which is usually collocated with the phase combiner 
because that is a convenient place to install the combiner.  However, the 
convergence of all the feedlines at the combiner, very close to the center 
element, can create severe feedline-induced pattern distortion unless common 
mode suppression is deployed at the ends of each of the feedlines where they 
enter the combiner.  This is because the outsides of the coax feedline shields 
form what looks like a field of wires that intersect near the center of the 
array, much like a radial system. The pattern distortion is created by common 
mode currents on the feedlines coupling to the center element, even though 
there is no direct electrical connection to the center element.

 

I never gave consideration to this effect until I deployed my first prototype 
system in the field and discovered the pattern of the array was not very good 
despite VNA measurements on the combiner and preamps that showed accurate gain 
and phase.  I eventually discovered through antenna modelling that strong 
coupling exists between the feedline shields and the center element.  The 
addition of the feedline chokes at the combiner effectively breaks the 
electrical path for current flow on the outside of the shields of the feedlines 
where they intersect at the combiner.  This almost completely eliminates the 
pattern distortion.  Once I deployed the feedline chokes, the pattern cleaned 
up dramatically, just as the modelling predicted.  

 

The YCCC combiner does not incorporate the common mode suppression internally.  
This is best done on the feedlines themselves, installing feedline chokes a few 
feet away from the combiner.

 

73, John W1FV

 

 

From: Dennis W0JX [mailto:w...@yahoo.com] 
Sent: Tuesday, November 30, 2021 12:48 PM
To: topband@contesting.com; John Kaufmann
Subject: Feedline Choke Placement in RX systems

 

K9YC made an interesting comment in his post, saying that the feedline chokes 
would be most effective if placed at the antenna end of the feedline.

 

W1FV's 9 circle YCCC array has them right at the controller.

 

The older K7TJR combiner utilized no feedline chokes. However, I believe that 
Lee's new design has built in common mode protection on the combiner circuit 
board.

 

So what is the best way? Is placement dependent upon the combiner design?

 

BTW, K3LR is using 2.4 in #31 toroids with at least 24 turns of RG-179 as 
feedline chokes in his 8 circle HiZ array and I believe that there are chokes 
on both ends of the antenna feedlines. Of course, K3LR operates in a high 
intensity, multi-transmitter environment and may need all that choking.

 

73 Dennis W0JX

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Re: Topband: W1FV 9-Circle Feedline & control Line Chokes?

[John Kaufmann via Topband]

You can make a feedline choke with snap-on ferrites as follows:  wind 4
turns of the feedline through 5 snap-on cores of Fair-Rite part #0431176451.
The core has an inner diameter of about 3/4 inch and 4 turns of RG-6 is the
limit of what will fit in the core.  However, using 5 cores will provide a
large total choking impedance (~10 kohm) on 160.  A larger core will accept
more turns but at significantly more cost for the cores.  The advantage of
making chokes with RG-179 wound through smaller cylindrical cores is the
much lower cost, although it's a bit more work to make these chokes.

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Rich Dailey
Sent: Monday, November 29, 2021 8:14 AM
To: topband@contesting.com
Subject: Topband: W1FV 9-Circle Feedline & control Line Chokes?

Homebrewing a 9-circle vertical array, and I'm looking for opinions from
other 9-circle users on 
what chokes you're using on the feedlines (rg-6) at the switch box, and on
the control line. I can go the 
binocular core route with rg-174, as per W1FV's article, but would prefer
the simplicity of several turns through a snap-on choke. 
tnx! 
73 de Rich, N8UX 
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Re: Topband: Interesting observation and comment (Skewed Path Vs. Horizontal/Vertical Polarization)

[John Kaufmann via Topband]

On 160 and 80, I have an 8-circle vertical receiving array.  On very long
paths, it is not uncommon to see skewing.  The most common example is the
path to JA, where the direct path heading should be about 330 degrees from
my QTH in New England.  However, for the last couple winter seasons, when
the path has been open, it has almost always been skewed to the west or west
northwest.  It has been quite rare to have a true direct path to JA on
either 160 or 80 from here.  Because my array is strictly vertically
polarized with no horizontal component, the skewing appears to be occurring
in the vertical polarization dimension.  I don't have a directional
horizontal antenna to compare here.

Coinciding with this skewing to JA has been the almost complete absence of a
true northerly path over the pole into Asia, primarily zone 18.  In other
solar cycles, the over-the-pole path has opened for at least one or two
seasons at the bottom of the cycle, but not this most recent cycle.  

I might suspect there is some local source of skewing at my QTH that is
deflecting signals from the direct path heading, yet from time to time my
array does receive DX signals over the true short path to the northwest.  In
particular, KL7's are sometimes received from the correct NNW heading on 160
and 80.  For that reason, I tend to discount the possibility of locally
generated skewing.

73, John W1FV

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Re: Topband: Portable Flag follow up (DX Engineering preamp noise figure update)

[John Kaufmann via Topband]

I have the DX Engineering preamp that I use with the DX Engineering portable
flag and can confirm the 4.5 dB noise figure.  Using the methods I described
here in an earlier post, I measured the noise figure as between 4 to 5 dB. 

Also I measured the gain (S21) from 0.1 to 30 MHz with my VNA-2180.  It
comes out to be 32 dB at 1.8 MHz.  Overall the gain response is essentially
the same as what WD8DSB measured on a prototype of the preamp and reported
on his Web page (https://sites.google.com/site/portableflagantenna/).  There
is a broad dip in gain of about 1 dB in the middle of the HF range, but it's
inconsequential.

Finally I measured the input impedance (S11) of the DX Engineering preamp.
It varies a bit with frequency but when reported as SWR relative to 50 ohms,
it ranges between 1.2:1 and 1.5:1 over the HF range.  It will be a fine
match for the flag which has a 50 ohm feedpoint impedance.

Overall I think these are very good numbers for a relatively inexpensive
preamp that is portable and battery powered.  (Disclaimer:  I have no
affiliation with or commercial interest in DX Engineering).

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Don Kirk
Sent: Tuesday, March 9, 2021 6:22 PM
To: topband
Subject: Re: Topband: Portable Flag follow up (DX Engineering preamp noise
figure update)

I should have said the so the 4.5 dB noise figure is certainly not
unreasonable.

Sorry for the typo.
73,
Don (wd8dsb)

On Tue, Mar 9, 2021 at 6:20 PM Don Kirk  wrote:

> A couple of weeks ago there were a lot of postings about my portable flag
> for radio direction finding (for tracking down RFI), and someone asked
> about the DX Engineering preamp that was designed for use with my portable
> flag and specifically what the noise figure was for this preamp.  Tim
> (K3LR) said DX Engineering would measure it, and today he reported it
> measured 4.5 dB.
>
> Tim mentioned that there were trade offs in the design such as low current
> draw and high gain, so the 4.5 dB noise figure is certainly unreasonable.
> It really is the only preamp I now use with my portable flag, and very
> pleased with how it works.
>
> Just FYI,
> Don (wd8dsb)
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
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Re: Topband: FW: The WD8DSB mini-flag antenna (LONG!)

[John Kaufmann via Topband]

I think there may be some semantic confusion over the term "averaging" and
how averaging affects noise when making spectral measurements, so let me
clarify what I mean.  My comments are specific to the P3 but are fairly
general.

The P3 has an AVERAGE function.  It allows you to perform averaging of video
traces over time intervals between about 50 milliseconds and 1 second.  If I
am trying to measure the dBm value of random noise, the trace looks somewhat
ragged at the lowest averaging times.  The trace on the display will bounce
up and down several dB.  I want the average value of the trace because
that's what gives me the noise spectral level.  I can do some visual
averaging of the ragged trace to obtain the average.  However, enabling
longer averaging times in the P3 makes this easier because it reduces the
jaggedness and the trace converges to a pretty smooth one.  However, the
smooth trace has exactly the same *average* value as the jagged trace.
Anyone who has a P3 can demonstrate this to themselves.  So, when I say the
averaging hasn't reduced the noise level, it's the average level of the
noise that hasn't changed.  

On the other hand, if I really want to make a weak narrowband signal stick
out of the noise, then I will reduce the noise bandwidth of the spectrum
measurement.  The narrower bandwidth will filter out more noise in the RF
(not video) domain.  In the P3 you do this by reducing the frequency span.
With the P3 you can vary the frequency span between 200 kHz and 2 kHz.
Because the noise bandwidth is approximately span/450 in the P3, a 2 kHz
span, for example, should give a factor of 10 (or 10 dB) reduction in
average noise compared to a span of 20 kHz.  When dealing with narrowband
coherent signals, this can really make very weak signals become visible on
the display when they are virtually invisible in a larger measurement
bandwidth.

I hope this clears up any confusion.

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Jim Brown
Sent: Thursday, February 25, 2021 10:39 PM
To: topband@contesting.com
Subject: Re: Topband: FW: The WD8DSB mini-flag antenna (LONG!)

On 2/25/2021 5:16 PM, John Kaufmann via Topband wrote:
> The P3 averages power, not amplitude, so using longer averaging times just
> smooths the display and doesn't reduce random noise.

It has nothing to do with power. Last I looked, the P3 is reading and 
displaying the instantaneous voltage in the IF, and can be calibrated to 
voltage at the input.

I've been doing swept measurements of complex quantities for nearly 40 
years, first at audio frequencies and now at RF. Averaging DOES cause 
random contents of a bin to approach zero (or the noise floor), making 
correlated signals stand out. This has long been well understood.

I the principle to measure the dynamic response of broadcast signal 
processing in a peer-reviewed paper to the Audio Engineering Society in 
1986.  The test signal was a swept sine embedded deep in musical program 
material to the point that it was barely audible to a trained listener, 
and detected by a synchronized swept narrowband detector. Because the 
swept excitation and swept detector are synchronized, the measurement 
produces the complex response of the system, and program material, being 
non-coherent, averages out.

http://k9yc.com/AESPaper-TDS.pdf

73, Jim K9YC
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Re: Topband: FW: The WD8DSB mini-flag antenna (LONG!)

[John Kaufmann via Topband]

The P3 averages power, not amplitude, so using longer averaging times just
smooths the display and doesn't reduce random noise.

John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Jim Brown
Sent: Thursday, February 25, 2021 8:03 PM
To: topband@contesting.com
Subject: Re: Topband: FW: The WD8DSB mini-flag antenna (LONG!)

On 2/25/2021 2:29 PM, John Kaufmann via Topband wrote:
> The P3 noise measurement bandwidth was about 100 Hz in my measurements.
I hope that everyone realizes that setting a high value for averaging 
cancels non-correlated noise in spectrum displays, including the 
waterfall, greatly increasing the visibility of correlated signals and 
noise. Correlated can be understood as non-random, and includes nearly 
all ham transmission modes and most electronically generated noise like 
computer clocks, trash from electronic power handling and switch-mode 
power supplies.

73, Jim K9YC
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Re: Topband: FW: The WD8DSB mini-flag antenna (LONG!)

[John Kaufmann via Topband]

The P3 noise measurement bandwidth was about 100 Hz in my measurements.  
Quoting from the P3 user's manual, "the effective bandwidth of the P3 is 
generally one display pixel, which is approximately span / 450.  I used a span 
of 50 kHz, so it comes out to 111 Hz.  Because the relationship is only 
approximate, I round it to 100 Hz in my calculations, which is good enough for 
my purposes.  To obtain the noise density in a 1 Hz bandwidth, you just 
subtract 20 dB (a factor of 100 for the difference in bandwidth) from the 
measured noise level in the P3.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of Lee STRAHAN
Sent: Thursday, February 25, 2021 4:46 PM
To: topband@contesting.com
Subject: Topband: FW: The WD8DSB mini-flag antenna (LONG!)


Hi John,
   What did you use as the P3 bandwidth for your noise measurement?  And 
conversion to 1Hz equivalent.
 The P3 has its own bandwidth and is not affected by setting the receiver 
bandwidth.
Lee  K7TJR OR

(Note:  what follows is a long, technical discussion about noise and “small” 
antennas.  I invoke some math and physics here, so if you are not comfortable 
with it, feel free to disregard or delete this e-mail.  I went through this 
exercise to help teach myself the limits here and maybe others might find it 
helpful or educational as well.)

  
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Re: Topband: The WD8DSB mini-flag antenna (LONG!)

[John Kaufmann via Topband]

 the extension on my 
antenna if I'm doing some stationary tests in my backyard, otherwise I use it 
as shown on the cover of QST.

 

I Really appreciate you jumping in so quickly on the antenna build and 
reporting some of your results.  Sometimes when I have a few minutes I will go 
outside and just play with the antenna and marvel on how simple it is, but how 
well it works. 

 

I hope I have now covered the majority of everyones questions and comments.  If 
there are other comments or questions we probably should move this discussion 
over to the RFI Reflector or e-mail me direct.

 

73,

Don (wd8sb)

 

On Tue, Feb 23, 2021 at 1:26 PM John Kaufmann via Topband 
 wrote:

Some of you may have seen the article by WD8DSB in the latest issue of QST.
I believe WD8DSB is on this reflector.  His article describes a mini-flag
antenna that can be used for direction-finding.  The neat thing about this
antenna, besides its compact size, is that it is unidirectional and is very
broadband.  It works from the AM BCB through 10m.  It produces a sharp null
off the back which allows you to determine signal direction without the
direction ambiguity you get with a conventional unterminated loop.



DX Engineering is producing this antenna as a kit, along with a companion
preamp.  (Disclaimer:  I have no affiliation or commercial interest in DX
Engineering).  See:  https://www.dxengineering.com/parts/dxe-noiseloop.  I
just bought the flag kit last week and finished assembling it this past
weekend.  I see today that the kit is now back-ordered until April so it was
good that I ordered it as soon as I saw the QST article.  



It took me about 3 hours to assemble the mini-flag even though the DXE Web
site says it can be done in 1-2 hours.  There is a bit of fussy mechanical
assembly involved in getting the symmetry and dimensions just right,
although it's not hard work.  The flag is 42 inches wide and 21 inches tall.
The DXE version of the antenna has slightly smaller dimensions than those
given in the QST article, which results in a small reduction in gain, which
doesn't really matter, but the pattern is the same.



I did some testing of the mini-flag in the AM BCB.  The gain is very
low--about -65 dBi on 160m--so it needs a good preamp.  I used a homebrew
preamp made up of a couple of MMIC's that produce about 35 dB of gain.  The
DXE preamp for this antenna won't be available until April.  On the higher
frequencies, less preamp gain is needed because the gain of the mini-flag
increases with frequency.



My initial tests indicate this antenna clearly works.  By rotating the flag
for the deepest null, I could nail the heading an AM BCB station to a few
degrees.  



This antenna could also be used as directional receiving antenna on its own
Although it is not hugely directive, it can be rotated easily to peak or
null signals or noise, and it is better than a conventional unterminated
loop.  It has essentially the same RDF as other larger flag or pennant
antennas but is obviously far more compact.



This is a nice contribution by WD8DSB.  Now I have to go off with the
mini-flag and chase some local noise sources that have been plaguing me this
winter on the low bands.



73, John W1FV



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Re: Topband: The WD8DSB mini-flag antenna

[John Kaufmann via Topband]

As a follow-up to my original post, here are a few additional comments.

Don, you mention that you designed the mini-flag for a deep null off the
back at low elevation angles, which is entirely understandable.  As I said
in my earlier post, the null is very pronounced in the AM BCB on local
groundwave signals.  However, I also see pretty significant nulls on
higher-angle signals, too.  Just a short time ago, I was listening to W1AW
on the low end of 160.  They are located only ~100 miles from me.  Their
signal has to be arriving at a pretty high angle, but the null is still
quite pronounced.

My homebrew preamp, that I mentioned in my post, uses a cascade of UTO 511
and UTO 533 mini-amplifier modules.  I used this preamp, not necessarily
because it's optimal, but because I already happened to have it on hand.
The gain of the 511 is given as 16 dB typical while the 533 is 17 dB, which
should yield a net gain of ~33 dB for the cascade of the two.  The noise
figure on the 511 that serves as the input amplifier is specified as 2.3 dB,
but its spec sheet gives an operational frequency range of 5-500 MHz, so I
can't be sure the noise figure (or the gain) holds up at lower frequencies.
Nonetheless I can hear the ambient noise in my receiver increase on 160m
when I connect the mini-flag to the preamp, which suggests the noise figure
for this preamp is at least adequate at my location.  I use a Yaesu FT-817ND
"backpack" radio as a portable radio with this antenna.

In EZNEC I calculate the RDF of this mini-flag as 7.4 dB on 160m at a 20
degree elevation angle.  That's essentially the same as the K9AY loop or
other similar pennant/flag antennas.  For use as a receiving antenna, the
important thing is the noise figure of the preamp.  The DX Engineering Web
site does not give the noise figure of their preamp.  Don, perhaps you know?

The other thing that might degrade the antenna is common-mode signal pickup,
which can be a problem for very low gain antennas where you are working with
very small signals.  However, based on what I observe in terms of antenna
pattern for this mini-flag, I can't say that I see any pattern effects that
might be attributable to common mode degradation.  Don, maybe you can
comment here as well on this aspect of the antenna.

As I also mentioned in my earlier post, the dimensions of the DXE
implementation are somewhat smaller than what's given in the QST article.
For me, that works out well because the width of the DXE mini-flag just
manages to fit inside the trunk of my mid-size sedan.  A wider flag would
not fit.

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Don Kirk
Sent: Tuesday, February 23, 2021 5:22 PM
To: wb6r...@mac.com
Cc: Top Band List List
Subject: Re: Topband: The WD8DSB mini-flag antenna

HI Steve,

Thanks for the nice implementation comment.

The portable flag front to back ratio is highly related to the elevation
angle and frequency of operation (just like any terminated loop), and
therefore I did not want to overstate the front to back ratio in my
portable flag article.  I designed the portable flag for direction finding
local RFI (ground wave based signals) and therefore made sure I selected an
appropriate termination resistor to provide a very deep null at low
elevation angles on 160, 80 and 40 meters where I often deal with RFI (the
portable flag has a very high front to back ratio at low elevation angles),
and because of this it also has exceptional front to back ratio at low
elevation angles down in the AM Broadcast Band.  Very small flags have just
as good front to back ratio and RDF as a full size flag as long as the
appropriate termination resistor is used.  The problem is when the flag
becomes too large for the frequency of operation which causes the
directional properties to degrade.  You can see some front to back ratio
vs. elevation plots for my portable flag on my simple portable flag website
and here is the URL to that site:
https://sites.google.com/site/portableflagantenna/home

Problem with very small flags is that the noise figure of the preamp
becomes a critical parameter, and because of this I don't recommend
attenuators be placed before the preamp as this causes degradation in the
signal to noise ratio.  I stumbled upon this issue when doing field tests
on one of the DX Engineering prototype preamps, and had them change the
design so the attenuators now come after the actual amplifier stage which
solved the problem.

Everything I said above about the performance of very small terminated
loops assumes no interaction with surrounding objects, and ignores issues
related with feedlines since the feedline is very short on the portable
flag.

P.S. I make no money from DX Engineering as I agreed to not be paid in
order to keep the price of the portable flag as low as possible.

73,
Don (wd8dsb)
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Searchable Archives: http://www.contesting.com/_topband - 

Topband: The WD8DSB mini-flag antenna

[John Kaufmann via Topband]

Some of you may have seen the article by WD8DSB in the latest issue of QST.
I believe WD8DSB is on this reflector.  His article describes a mini-flag
antenna that can be used for direction-finding.  The neat thing about this
antenna, besides its compact size, is that it is unidirectional and is very
broadband.  It works from the AM BCB through 10m.  It produces a sharp null
off the back which allows you to determine signal direction without the
direction ambiguity you get with a conventional unterminated loop.

 

DX Engineering is producing this antenna as a kit, along with a companion
preamp.  (Disclaimer:  I have no affiliation or commercial interest in DX
Engineering).  See:  https://www.dxengineering.com/parts/dxe-noiseloop.  I
just bought the flag kit last week and finished assembling it this past
weekend.  I see today that the kit is now back-ordered until April so it was
good that I ordered it as soon as I saw the QST article.  

 

It took me about 3 hours to assemble the mini-flag even though the DXE Web
site says it can be done in 1-2 hours.  There is a bit of fussy mechanical
assembly involved in getting the symmetry and dimensions just right,
although it's not hard work.  The flag is 42 inches wide and 21 inches tall.
The DXE version of the antenna has slightly smaller dimensions than those
given in the QST article, which results in a small reduction in gain, which
doesn't really matter, but the pattern is the same.

 

I did some testing of the mini-flag in the AM BCB.  The gain is very
low--about -65 dBi on 160m--so it needs a good preamp.  I used a homebrew
preamp made up of a couple of MMIC's that produce about 35 dB of gain.  The
DXE preamp for this antenna won't be available until April.  On the higher
frequencies, less preamp gain is needed because the gain of the mini-flag
increases with frequency.

 

My initial tests indicate this antenna clearly works.  By rotating the flag
for the deepest null, I could nail the heading an AM BCB station to a few
degrees.  

 

This antenna could also be used as directional receiving antenna on its own.
Although it is not hugely directive, it can be rotated easily to peak or
null signals or noise, and it is better than a conventional unterminated
loop.  It has essentially the same RDF as other larger flag or pennant
antennas but is obviously far more compact.

 

This is a nice contribution by WD8DSB.  Now I have to go off with the
mini-flag and chase some local noise sources that have been plaguing me this
winter on the low bands.

 

73, John W1FV

 

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Re: Topband: UA9BA Spitfire antenna

[John Kaufmann via Topband]

This antenna was clearly working well at UA2FW in the recent CQ 160 contest.
When I listened on the band, UA2FW was, by far, the strongest signal coming
out of Europe in mediocre conditions.  Normally northern Europe, including
UA2, is at a disadvantage in terms of propagation to the US.  Also, UA2FW
has the highest claimed multi-op score in the CQ 160 contest, so it's a
remarkable achievement.

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Alexander Teimurazov
Sent: Wednesday, February 10, 2021 10:44 AM
To: 'TopBand List'
Subject: Topband: UA9BA Spitfire antenna

https://dxnews.com/ua9ba-spitfire-160m/

 

 73   Al 4L5A

 

 






 

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Re: Topband: RG6 recommendations

[John Kaufmann via Topband]

Hi Charlie, 

What you see in your TDR sweep of the RG6 is absolutely normal.  I've seen 
exactly the same thing.  The rise in apparent impedance with distance is caused 
by the loss in the cable.  If you had a lower loss cable, the TDR trace would 
be flatter.  As long as you don't seen any significant bumps or dips, your 
cable run is fine.

For use with Beverage antennas, the loss in the RG6 is inconsequential unless 
maybe you have an extremely long run of cable (thousands of feet).   

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of Charles Stackhouse via Topband
Sent: Sunday, January 24, 2021 8:33 PM
To: topband@contesting.com
Subject: Topband: RG6 recommendations

After a period of inactivity, I set out to get my station going again. The 
Beverages were not working with very low signal levels and I replaced 600 foot 
RG6 feedline from shack to Beverage switch in the woods with new RG6 which 
still had the plastic wrap around the spool.
I was surprised when things were no better. The "new" coax is not right. The 
TDR sweeps show a straight line increase in impedance from 78 ohms to 95 ohms. 
There are no impedance "bumps" seen. The 400 feet left on the spool do the same 
thing as does 800 feet of the same stuff bought at the same time.
This stuff was bought on Ebay and is gel-flooded RG6 labelled "Commscope Inc. 
GA390709 and GA3907022." I bought it in Sept 2014 and it has been stored ever 
since in a dry heated basement.
Using an oscilloscope as a TDR I see that the impedance line is not level as 
with good coax but slopes  upward at an angle.  I also checked by placing a 330 
ohm resistor at the end of the cable and ran an SWR trace from 1-8 MHz with the 
SWR only 2-2.5. 
Why is this cable so lossy? Was it bad to begin with or did it deteriorate in 7 
years?
What recommendations for good RG6 can anyone make. There has been lots of 
critter chewing upon cables in the past so I guess gel-flooded cable would be 
preferable. Should I spend $230 for DXEngineerings good stuff or can I get by 
cheaper? 
p.s. I went out and checked each Beverage at the switchbox today and 4 out of 6 
were great. Only 3" of snow and temp was about 25 deg F. I was able to keep the 
snow and dielectric grease off of my laptop.
73, Charlie W2GN
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Re: Topband: Best conditions of the season

[John Kaufmann via Topband]

We got a piece of the action, too, in New England.  I worked JH1HDT, HL5IVL, 
and VK6LW just before my SR.  HL5IVL peaked up to 579 right at SR.  We only get 
propagation to HL very infrequently here in W1.  JA7BXS was in there but he 
first fired up on the disturbance on 1825 and was being obliterated by it.  He 
later moved to 1820 but a BCB spur took him out there, too. 

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of Ron Spencer via Topband
Sent: Friday, December 11, 2020 8:11 AM
To: topband
Subject: Topband: Best conditions of the season

160 was excellent this morning. Early (1138 with sunrise at 1214) heard, and 
worked, Tad, JH1HDT. Not long after worked Kim HL5IVL. Kevin VK6LW answered my 
CQ as did AL7JI (not in that order). Worked Adrian, VK2WF.  Worked Takar, 
JA7BXS too even though he was zero beat on 1820 with a BC signal making it 
difficult. Almost 20 minutes after SR still hearing Kim and Tad. Hope we have 
more of these kind of days! Thanks all for the Qs. 



Ron

N4XD

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Re: Topband: EZNEC Ground Errors

[John Kaufmann via Topband]

I have two receiving antennas on 160:  an 8-circle vertical array and a low
dipole up 10 feet.  I have been noticing that in the first part of the
evening, the dipole often hears Europe as well as, or nearly as well as, the
8-circle.  This appears to indicate that the signals are arriving at
relatively high angles.   This might also explain why a transmit dipole at a
moderate height can work well for DX.  Other times, the dipole is way down
from the 8-circle, and I would expect a vertical transmit antenna to do
better.

Occasionally in the mornings, around SR, the dipole also hears the DX as
well as or sometimes better than the 8-circle.

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Artek Manuals
Sent: Friday, December 11, 2020 9:39 AM
To: topband@contesting.com
Subject: Re: Topband: EZNEC Ground Errors

OR

The propagation mode on 160 is not what we have popularly come to "Accept".

There is a growing body of evidence that particularly at gray line that 
signals often arrive at a higher angles. This is often attributed to 
"ducting" . Maybe a lot more of 160 intercontinental propagation is  due 
ducting rather than the more commonly thought of low angle earth to F 
layer hop/multi-hop stuff seen at higher frequencies?

Where do i get a pair of those glasses that lets me look at radio waves 
so I actually see them arrive

Dave
NR1DX

On 12/11/2020 8:58 AM, Roger Kennedy wrote:
> Guy I have ALWAYS thought that the various Computer-based modelling of
> Ground and its effect on Antennas is WAY off . . .
>
> And surely the errors are MOST significant on 160m, not just because
> Antennas are near the ground (in wavelength terms) . . . but also because
> even the ground 130 ft deep is still going to have an effect . . . and
there
> is no way EZNEC can possibly take that into account, even if you KNEW what
> was underneath your topsoil !
>
> In my particular case it's not the effect on Verticals on 160m that
interest
> me . . . it's the effect on a Low Dipole.
>
> Any DX stations I work on 160m will confirm I put out a pretty respectable
> signal . . . my signal reports around the world and more recently I am
able
> to compare my RBN Reports across NA and they tend to be very similar to
the
> other British DXers.
>
> However, most people are surprised to discover that for the last 50 years
I
> have always used a Horizontal Half Wave dipole on 160m, at around 50ft.
>
> BUT I believe that EZNEC plots showing that most of the RF is just very
High
> Angle is WRONG . . . that's because in practice the Ground underneath it
is
> rubbish . . . so the Dipole's effective height above Ground is much
higher.
>
> And in fact, it seems that most people who have Dipoles on 160m mounted
over
> or near a very comprehensive Radial system DO get poor results using them
> for DX . . . but that goes to confirm my theory (which is all based on my
> actual experience on Top Band)
>
> Roger G3YRO
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
Reflector

-- 
Dave manu...@artekmanuals.com www.ArtekManuals.com

-- 
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

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Re: Topband: I identified signal on 1.825 MHz this morning

[John Kaufmann via Topband]

Here in the Boston area it was peaking from the SW on my 8 circle array.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of w...@w5zn.org
Sent: Friday, December 11, 2020 7:24 AM
To: David Raymond
Cc: topband@contesting.com; Topband
Subject: Re: Topband: I identified signal on 1.825 MHz this morning

Signal is ~45 degrees from EM45 Arkansas. running about 15 dB above my 
noise floor.

73 Joel W5ZN


On 2020-12-11 05:15, David Raymond wrote:
> Signal bearing from central Iowa/EN21 is about 70 degrees based on
> some interpolation from the 8 circle array.
> On 12/11/2020 6:06 AM, Don Kirk wrote:
>> I’m hearing a very strong pulsating signal that sounds like it might 
>> be
>> some kind of digital communications and it’s bearing is approximately 
>> 73
>> degrees from my QTH near Indianapolis and wonder if others are hearing 
>> it
>> at at what heading and does anyone recognize what it is? It’s on right 
>> now
>> at 7:06 AM
>> 
>> Don wd8dsb
>> _
>> Searchable Archives: http://www.contesting.com/_topband - Topband 
>> Reflector
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband 
> Reflector
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Re: Topband: Need Opinion on DXE RPS-1 or RPS-2 Preamp

[John Kaufmann via Topband]

I have the RPA-1, the predecessor to the RPA-2.  It's an outstanding preamp 
with a low noise figure and very high dynamic range.  I'm sure it would make a 
fine BOG preamp.

73, John W1FV



-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of Edward via Topband
Sent: Thursday, December 3, 2020 4:43 AM
To: topband@contesting.com
Subject: Re: Topband: Need Opinion on DXE RPS-1 or RPS-2 Preamp

Sorry.  Meant RPA 1 or 2. 

> On 3 Dec 2020, at 12:38 PM, Edward  wrote:
> 
> Any good?  If not this one, which preamp would you recommend for a BOG 
> antenna?

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Re: Topband: FT8 clutter on the DX Cluster

[John Kaufmann via Topband]

I use the VE7CC node for spots.  You can filter out FT8 spots on VE7CC via the 
'set/noft8' command.

73, John W1FV

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Re: Topband: 8 vs 4 direction 4-SQ?

[John Kaufmann via Topband]

For signals that arrive from directions that are in between the main lobe 
headings of a 4-square, you will lose up to a few dB of S/N compared to having 
8 directions.  Whether that matters to you is purely a personal performance vs. 
complexity/cost decision.  If 90% of what you work is covered by 4 directions, 
then 4 directions may be good enough.  If you don't want to give up any 
performance in any direction, then go for 8 directions.  There is no right or 
wrong answer.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] 
On Behalf Of Gary K9GS
Sent: Thursday, March 19, 2020 3:11 PM
To: topband@contesting.com
Subject: Topband: 8 vs 4 direction 4-SQ?

A couple of companies, LBS and RemoteQTH, have started selling 8 direction 4- 
SQ controllers.I'm trying to understand if this would be worthwhile. My 
reasoning is that the main lobe is so broad you have the in-between 45 degree 
directions covered anyway. Thoughts?73,Gary K9GS
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Re: Topband: NVIS Antenna

[John Kaufmann via Topband]

Inverted vee dipoles do produce some vertically polarized radiation off the
ends.  However, that vertical component has maximum gain at zenith, i.e.
straight overhead.  It does not contribute to any significant low-angle
radiation.  You can see this by doing an antenna model.

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Jim Brown
Sent: Sunday, March 15, 2020 2:36 PM
To: topband@contesting.com
Subject: Re: Topband: NVIS Antenna

Hi Ed,

I've studied this extensively for horizontally polarized antennas, but 
only for flat ones; I thin that inverted Vees have some vertical 
components.

For horizontally polarized antennas, maximum gain at high angles occurs 
at a mounting height of about 75 electrical degrees, and falls by only 
about 1 dB if raised to 120 electrical degrees. By "high," I'm talking 
70 degrees elevation.

Also, RX is different from TX, in that with RX we don't care about loss, 
only signal to noise. Ground loss is a contributor to those variations 
based on mounting height. N6RO, an old hand on topband with a great 
antenna farm, rearranges his M/6 station for topband contests to bring 
LOTS of his antennas to the station he uses single-op.

That study is here.  http://k9yc.com/AntennaPlanning.pdf

73, Jim K9YC


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Re: Topband: Slightly OT - amplifier noise

[John Kaufmann via Topband]

Steve,

An alternative is to do the cancellation with all passive circuitry.  You
can find some designs on the Web but you'll have to build them yourself. An
example (one that I built) is this one from WA1ION:
https://www.pa4tim.nl/wp-content/uploads/2011/02/passive_bb_phasing.pdf.
The drawback to the passive designs is the insertion loss.  The WA1ION
design works quite well but I've measured its insertion loss as about 12 dB.
That may not be acceptable in many situations, particularly on the higher HF
bands.

73, John W1FV  

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of n2ica...@gmail.com
Sent: Saturday, March 14, 2020 12:41 PM
To: Topband
Subject: Topband: Slightly OT - amplifier noise

This discussion of Hi Z amplifiers has been quite interesting. Excellent 
information from W1FV and K7TJR.

I have an RX amp question, related but slightly off-topic.

I have an MFJ-1025/1026 noise canceler. I like to use it on the higher HF
bands 
to cancel power line QRN. The noise is typically S3-S4, but I want it down
to S0 
to hear the bottom layer of stations. My sense antenna works fine, and the
QRN 
is canceled. However, the MFJ-1025 amplifier noise is quite significant,
often 
negating the QRN cancellation. The MFJ amplifiers are J310's. Any 
recommendations for something quieter ?

73,
Steve, N2IC

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Re: Topband: Hi Z amplifiers for 160m (LONG)

[John Kaufmann via Topband]

f the main lobe 
goes up by 20*log(2) = 6dB. That would imply that the gain of the array 
has gone up by 6dB and that the azimuth beamwidth of the main lobe has 
gone down by a factor of 4. However, if you look at gain of a linear 
broadside array when you double the number of elements (assuming 
constant element spacing), the gain goes up by at most 3dB. If the 
average gain for the isotropic atmospheric noise is a constant 0dB, then 
signal-of-interest in the antenna bore site can only go up by at most 
3dB relative to the atmospheric noise. But the mathematical sum of the 
components of the signal-of-interest have gone up 6dB, so the 
mathematical sum of the components of the isotropic atmospheric noise 
have to go up by at least 3dB.

I think I have this right, John, but feel free to shoot holes in it if I 
don't. I know thinking about it made my head hurt.

73, Mike W4EF

On 3/12/2020 4:37 PM, John Kaufmann via Topband wrote:
> To assess the impact of amplifier circuit noise in "active" receive arrays,
> we only need to be concerned with the contribution of amplifier circuit
> noise relative to atmospheric noise.   The details of how signals are phased
> in any particular array do not matter.  The objective is to keep the total
> contribution of amplifier noise far below the atmospheric noise so as not to
> degrade the overall system noise floor in any significant way.  However, we
> need to understand that the combiner circuit that phases up the signals in a
> receive phased array responds very differently to amplifier noise and
> atmospheric noise.  This makes it less obvious how to determine whether the
> circuit noise of a particular amplifier is "low enough".  Fortunately, there
> is a simple way to determine that using basic principles.
>
> Let's start with a single amplified vertical antenna.  To simplify the
> analysis, we just set the gain of the vertical to 0 dB.  In practice we can
> do a NEC analysis to calculate absolute gain in dBi, factoring in real
> losses but that is not necessary and does not change the conclusions.  The
> antenna feedpoint amplifier adds its own noise to whatever signal plus
> atmospheric noise is received by the vertical.  Let's set the circuit noise
> power equal to one "circuit noise unit" and the atmospheric noise power to
> one "atmospheric noise unit".  Of course we can put voltage (or power)
> numbers on those units, based on properties of the amplifier, the
> atmospheric noise, the actual antenna gain, and the measurement bandwidth.
> However, that makes things unnecessarily complicated, so we won't do that.
>
> Next we create an array of N amplified vertical antennas, each one identical
> to the single vertical we started out with.  We feed the signals from all
> the antenna amplifiers into an ideal combiner circuit that does not add its
> own noise.  The combiner circuit phases up signals to create a directive
> beam pattern.  Now we ask how much atmospheric noise appears in the phased
> up sum compared to the amount of total amplifier circuit noise.
>
> The atmospheric noises received at the various verticals are all correlated.
> The correlation comes about because the atmospheric noise is the same at
> each vertical except for time delay differences caused by geometric path
> length differences to each antenna element.  However, as I described in an
> earlier e-mail, the amplifier circuit noises coming from each of the antenna
> amplifiers are all uncorrelated.
>
> For uncorrelated noises, the combiner simply adds the circuit noise powers
> of the individual amplifiers as I described previously.  For N elements with
> N amplifiers, the total circuit noise power out of the combiner is then N
> times one "circuit noise unit" (ignoring any additional gain or throughput
> loss imparted by the combiner circuit).
>
> To determine the total atmospheric noise coming out of the combiner circuit,
> let's assume the atmospheric noise has a completely uniform distribution in
> 3-dimensional space.  That is, the strength of the atmospheric noise is the
> same in every direction.  This is an idealized assumption, but is often a
> reasonable approximation to reality.  Under these assumptions, the total
> atmospheric noise out of the combiner turns out to be just one "atmospheric
> noise unit"!  In other words, it is exactly the same as the atmospheric
> noise coming out of a single vertical.  This is because the total
> atmospheric noise power picked up by the array is just the gain of the array
> (relative to a single vertical) averaged over all of 3-dimensional space
> times one "atmospheric noise unit" (the noise picked up by a single
> vertical).  That average gain is exactly 0 dB, so the total atmospheric
> noi

Re: Topband: Hi Z amplifiers for 160m (LONG)

[John Kaufmann via Topband]

To assess the impact of amplifier circuit noise in "active" receive arrays,
we only need to be concerned with the contribution of amplifier circuit
noise relative to atmospheric noise.   The details of how signals are phased
in any particular array do not matter.  The objective is to keep the total
contribution of amplifier noise far below the atmospheric noise so as not to
degrade the overall system noise floor in any significant way.  However, we
need to understand that the combiner circuit that phases up the signals in a
receive phased array responds very differently to amplifier noise and
atmospheric noise.  This makes it less obvious how to determine whether the
circuit noise of a particular amplifier is "low enough".  Fortunately, there
is a simple way to determine that using basic principles.

Let's start with a single amplified vertical antenna.  To simplify the
analysis, we just set the gain of the vertical to 0 dB.  In practice we can
do a NEC analysis to calculate absolute gain in dBi, factoring in real
losses but that is not necessary and does not change the conclusions.  The
antenna feedpoint amplifier adds its own noise to whatever signal plus
atmospheric noise is received by the vertical.  Let's set the circuit noise
power equal to one "circuit noise unit" and the atmospheric noise power to
one "atmospheric noise unit".  Of course we can put voltage (or power)
numbers on those units, based on properties of the amplifier, the
atmospheric noise, the actual antenna gain, and the measurement bandwidth.
However, that makes things unnecessarily complicated, so we won't do that.

Next we create an array of N amplified vertical antennas, each one identical
to the single vertical we started out with.  We feed the signals from all
the antenna amplifiers into an ideal combiner circuit that does not add its
own noise.  The combiner circuit phases up signals to create a directive
beam pattern.  Now we ask how much atmospheric noise appears in the phased
up sum compared to the amount of total amplifier circuit noise.  

The atmospheric noises received at the various verticals are all correlated.
The correlation comes about because the atmospheric noise is the same at
each vertical except for time delay differences caused by geometric path
length differences to each antenna element.  However, as I described in an
earlier e-mail, the amplifier circuit noises coming from each of the antenna
amplifiers are all uncorrelated.

For uncorrelated noises, the combiner simply adds the circuit noise powers
of the individual amplifiers as I described previously.  For N elements with
N amplifiers, the total circuit noise power out of the combiner is then N
times one "circuit noise unit" (ignoring any additional gain or throughput
loss imparted by the combiner circuit).

To determine the total atmospheric noise coming out of the combiner circuit,
let's assume the atmospheric noise has a completely uniform distribution in
3-dimensional space.  That is, the strength of the atmospheric noise is the
same in every direction.  This is an idealized assumption, but is often a
reasonable approximation to reality.  Under these assumptions, the total
atmospheric noise out of the combiner turns out to be just one "atmospheric
noise unit"!  In other words, it is exactly the same as the atmospheric
noise coming out of a single vertical.  This is because the total
atmospheric noise power picked up by the array is just the gain of the array
(relative to a single vertical) averaged over all of 3-dimensional space
times one "atmospheric noise unit" (the noise picked up by a single
vertical).  That average gain is exactly 0 dB, so the total atmospheric
noise doesn't change in our idealized system.  It doesn't matter what the
antenna pattern is; the average gain is always 0 dB, which is why we did not
need to be concerned with details of how signals are phased up to form a
beam pattern.  Of course, a different gain applies to actual signals that
are coming from a specific direction and are not uniformly distributed like
atmospheric noise, which is why we see a S/N improvement when the array is
aimed at a signal of interest.

So, we have demonstrated that in relative terms, the amplifier circuit noise
power in an array of N amplified antennas goes up by a factor N whereas the
atmospheric noise does not change.  That increase in the amplifier noise
contribution relative to atmospheric noise degrades the overall noise figure
of the system.  However, as long as we keep the amplifier noise contribution
small enough, the noise figure degradation can also be kept to a minimum.
That is why having more amplified elements makes it more important to design
the antenna amplifiers for low circuit noise.

73, John W1FV






-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Michael Tope
Sent: Thursday, March 12, 2020 4:37 PM
To: topband@contesting.com
Subject: Re: Topband: Hi Z 

Re: Topband: Hi Z amplifiers for 160m

[John Kaufmann via Topband]

Lee,
I think you are confusing voltage and power.  For incoherent sources like 
amplifier noise, the voltages of multiple incoherent sources add in a 
root-sum-squared (RSS) fashion.  The voltage of the sum of eight incoherent 
sources is square root of eight times a single noise source, assuming equal 
combining ratios.  However, because power is proportional to the square of 
voltage, then the *power* of the combined sum is the sum of the individual 
noise powers.  This is well known in the theory of random processes, which is 
the basis of communications theory.  So, what I said earlier is correct.  For a 
system with eight amplifiers, the effective total noise power in the sum is 
eight times the individual noise powers when the sources are combined with 
equal weights.  The YCCC array does not use equal weights, so the powers have 
be weighted when combining them to get the total noise power.
73, John W1FV


-Original Message-
From: Lee STRAHAN 
To: topband@contesting.com 
Sent: Wed, Mar 11, 2020 10:22 pm
Subject: Re: Topband: Hi Z amplifiers for 160m

  Hello John and all,
  Concerning the adding the noise in a typical array. If the noise was coherent 
or exactly the same signal from each element/amp the summed noise would indeed 
be 8 times. However circuit noise is always random and incoherent which causes 
the summation to be a single noise power times the square root of the number of 
elements assuming equal levels from each amp. In the case of 8 elements 4.5 dB 
increase which is no small matter as well. In the case of the three elements 
the noise summation would be about 2.4 dB higher than a single element.
Lee  K7TJR  OR

As the designer of the YCCC high impedance feedpoint amplifier, let me address 
some issues related to the design of the YCCC amplifier as well as feedpoint 
amplifiers in general.  If you don't want to read a lot of technical 
gobbledygook, please disregard this message.

The YCCC uses an AD8055 RF amp as the gain element.  As Lee, K7TJF, points out, 
there are most certainly better op amps out there.  However, the AD8055 was the 
"best" part I could find in a DIP-8 package.  The "better" op amps are all SMT 
parts but given that the YCCC preamp was a kit, I intentionally limited the 
selection to DIP-8 parts that kit builders could work with relatively easily on 
a PCB.  Not everyone is able to do a competent job soldering tiny SMT parts.

Within the universe of available RF op amps, tradeoffs must be made in terms of 
noise, linearity, and bandwidth.  The AD8055 is not the lowest noise part but 
it has excellent linearity and plenty of bandwidth for HF use.  At my QTH there 
is an AM BCB station 3 miles away, which makes it a somewhat challenging EMI 
environment.  The decision to run the op amp in a unity gain configuration 
comes down to linear dynamic range.  It is easy to design for more gain, but it 
is also easily demonstrated that you will begin to suffer in terms of unwanted 
intermods.  With the YCCC preamp, I get absolutely zero BCB intermods or 
distortion products in the 160m band at my QTH.

In general I do not like to use an outboard preamplifier between the output of 
the phased array combiner circuit and my receiver because it degrades the 
linear dynamic range of the system.  The YCCC system user's manual (Section
12.1) does specify several outboard preamps that could be used.  In a low EMI 
environment, I think they all work fine.  However, at my QTH, with the nearby 
AM BCB station, all of them, without exception, generate increased distortion 
and intermod, which I find unacceptable.  

It is always desirable to apply RF gain with a roofing filter in front, which 
is becoming common practice in high performance receivers.  With my K3S 
receiver, the use of a unity gain antenna feedpoint preamplifier is perfectly 
fine if you also turn on the preamp in the K3S.  This gives the best overall 
linear dynamic range with a preamplified short vertical system.
There is no loss in noise performance because the noise on 160 and 80 is 
totally dominated by atmospheric noise.  In measurements I made at my QTH, the 
internal noise of the YCCC preamp is about 10 dB lower than my daytime 
atmospheric noise on 160m when using a vertical about 20 feet high.

You must also consider the number of active elements in an amplified antenna 
array when evaluating overall system noise performance.  This is because the 
amplifier circuit noise power of all the feedpoint amplifiers is added together 
when the elements are phased up in a combiner.  If you have N elements in your 
array, the effective circuit noise contribution gets multiplied by N.  The YCCC 
array has 3 active elements at a time.  However, the YCCC design is somewhat 
unusual in that maximum RDF is achieved when the signals from the elements are 
combined in unequal ratios.  As a result the effective amplifier circuit noise 
contribution is less than 3 times (or 4.8
dB) the noise of a single amplifier.  

Re: Topband: Hi Z amplifiers for 160m

[John Kaufmann via Topband]

As the designer of the YCCC high impedance feedpoint amplifier, let me
address some issues related to the design of the YCCC amplifier as well as
feedpoint amplifiers in general.  If you don't want to read a lot of
technical gobbledygook, please disregard this message.

The YCCC uses an AD8055 RF amp as the gain element.  As Lee, K7TJF, points
out, there are most certainly better op amps out there.  However, the AD8055
was the "best" part I could find in a DIP-8 package.  The "better" op amps
are all SMT parts but given that the YCCC preamp was a kit, I intentionally
limited the selection to DIP-8 parts that kit builders could work with
relatively easily on a PCB.  Not everyone is able to do a competent job
soldering tiny SMT parts.

Within the universe of available RF op amps, tradeoffs must be made in terms
of noise, linearity, and bandwidth.  The AD8055 is not the lowest noise part
but it has excellent linearity and plenty of bandwidth for HF use.  At my
QTH there is an AM BCB station 3 miles away, which makes it a somewhat
challenging EMI environment.  The decision to run the op amp in a unity gain
configuration comes down to linear dynamic range.  It is easy to design for
more gain, but it is also easily demonstrated that you will begin to suffer
in terms of unwanted intermods.  With the YCCC preamp, I get absolutely zero
BCB intermods or distortion products in the 160m band at my QTH.

In general I do not like to use an outboard preamplifier between the output
of the phased array combiner circuit and my receiver because it degrades the
linear dynamic range of the system.  The YCCC system user's manual (Section
12.1) does specify several outboard preamps that could be used.  In a low
EMI environment, I think they all work fine.  However, at my QTH, with the
nearby AM BCB station, all of them, without exception, generate increased
distortion and intermod, which I find unacceptable.  

It is always desirable to apply RF gain with a roofing filter in front,
which is becoming common practice in high performance receivers.  With my
K3S receiver, the use of a unity gain antenna feedpoint preamplifier is
perfectly fine if you also turn on the preamp in the K3S.  This gives the
best overall linear dynamic range with a preamplified short vertical system.
There is no loss in noise performance because the noise on 160 and 80 is
totally dominated by atmospheric noise.  In measurements I made at my QTH,
the internal noise of the YCCC preamp is about 10 dB lower than my daytime
atmospheric noise on 160m when using a vertical about 20 feet high.

You must also consider the number of active elements in an amplified antenna
array when evaluating overall system noise performance.  This is because the
amplifier circuit noise power of all the feedpoint amplifiers is added
together when the elements are phased up in a combiner.  If you have N
elements in your array, the effective circuit noise contribution gets
multiplied by N.  The YCCC array has 3 active elements at a time.  However,
the YCCC design is somewhat unusual in that maximum RDF is achieved when the
signals from the elements are combined in unequal ratios.  As a result the
effective amplifier circuit noise contribution is less than 3 times (or 4.8
dB) the noise of a single amplifier.  In fact because of the unequal
combining ratios, the actual effective noise goes up by a bit less than 2 dB
compared to a single amplifier.  An array like the Hi-Z array with 8 active
elements combines the elements in equal proportion so the effective
amplifier circuit noise of the system is 8 times (or 9 dB) higher than the
noise of a single amplifier.  For this reason, the YCCC array can tolerate
noisier amplifiers without degrading system noise performance.  The
objective is to keep circuit noise well under atmospheric noise.

On the subject of op amp noise specs, you must consider *both* input voltage
noise and input current noise because, in general, both contribute to the
total output amplifier noise.  It is not good enough to pick an op amp with
low input voltage noise without also considering the input current noise.
For a good noise analysis, download a copy of the datasheet for the CLC425
op amp:  http://www.elektronikjk.pl/elementy_czynne/IC/CLC425.pdf.  Refer to
pages 8-10.  (The CLC425 is a very good RF op amp but has been obsoleted by
newer parts).  I put the noise equations into an Excel spreadsheet, which
allowed me to compare many different op amps in terms of total noise
performance, using their input current noise and voltage noise specs.

Not all op amps publish specs on linearity.  It is safe to assume that if no
specs are given, the linearity is not particularly outstanding.  Look for
harmonic distortion (HD2 and HD3) as well as TOI (third-order intercept)
data.  You do have to be careful in interpreting the data because the
linearity is directly tied to the amplifier gain configuration.

If I were to recommend a particularly outstanding RF op amp, it would 

Re: Topband: Strong Carrier 1828.5

[John Kaufmann via Topband]

It's also very strong in the greater Boston area.  The signal is very steady
with only a few dB of very slow fading.  I get a heading of roughly SE,
which would put it towards Cape Cod or Rhode Island, but it could be
anywhere between E and S.  It doesn't exhibit strong directivity on my
8-circle array.

73, John W1FV

-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Don Kirk
Sent: Monday, January 20, 2020 6:43 PM
To: topband
Subject: Topband: Strong Carrier 1828.5

Receiving strong carrier on 1828.5 KHz that sounds like sky wave.  Its
currently peaking 30 db over my noise floor at 6:40pm EST (2340 UTC), and
it has an approximate heading of 55 degrees from the Indianapolis area
(Fishers IN) which puts it on a line that goes from my location through the
top of Maine.

Anyone else hearing it?

Don (wd8dsb)
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Topband: Message from HI3/KC1XX

[John Kaufmann via Topband]

Greetings Topbanders,

 

Matt, KC1XX, is spending the winter in HI3 and asked me to relay this
message to all of you.  He is on the air as HI3/KC1XX but is experiencing
terrible line noise at his present location.  He hears lots of stations
calling him on the low bands but he is having great difficulty pulling out
callsigns through the noise.  He apologizes to those who have been calling
without success.  However, Matt moves to a different location down there in
early February and the noise situation should improve.  At that time he
should be able to hear and work more of you.

 

73, John W1FV

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Topband: Source for durable ladder line?

[John Kaufmann via Topband]

I'm looking for a source for durable ladder line for making two-wire
reversible Beverages for use at the KC1XX contest station.  In the past
we've used the line sold by DX Engineering but over the years we've found
that the plastic spacers between the wires become brittle and break off.  It
may be UV exposure that causes this.  We also get some pretty severe weather
at KC1XX hilltop location, with ice in the winter and frequent strong winds.
The spacer breakage sometimes exposes the wires, which then become twisted,
and the ladder line generally becomes weakened and prone to wire breakage.

 

What else is available commercially?

 

73, John W1FV

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Re: Topband: 4sq vs SAL 30 Mkii in a forest

[John Kaufmann]

I have an 8-circle array in the woods.  The tallest trees in my area are about 
60-70 feet, so your trees might be larger and denser than mine.   However, my 
system works very well, judging by the fact that its pattern seems to match 
very closely the theoretical pattern for this array.  In other words, I 
seriously doubt that the trees are detuning or degrading my array in any 
significant way.  Some people believe that trees and foliage introduce 
attenuation, even on 160 meters, but as long as the attenuation is the same for 
every element in the array, it is of no consequence because these short 
verticals are already very inefficient.  I do try to keep the verticals a few 
feet clear of big trees and foliage, and periodically I trim away foliage that 
grows in around them.  

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Fischer
Sent: Monday, February 18, 2019 2:56 PM
To: topband@contesting.com
Subject: Topband: 4sq vs SAL 30 Mkii in a forest

Hi all, newb to the topband 160 reflector here so thank you for any coaching or 
corrections on protocol…

I live on a heavily forested (douglas firs - almost all of which are 100’+) 
piece of land. 

I have enough room left to put up either an SAL 30 or a  4sq of 20’ verts with 
80’ spacing. HiZ probably

Problem is regardless of which I choose, there will be at least one or two 
trees in the “infield“ and foliage around the edges.

Any experience with the same or  thoughts? Grateful for the coaching please 
feel free to reply direct to  mikebfisc...@comcast.net  

73
K7XH

Sent from my iPhone
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Re: Topband: Rx splinter

[John Kaufmann]

It just realized that the number of turns I specified (in my post below) to
use on the Fair-Rite binocular core will be a tight fit inside the core.
The number should be scaled down as follows:

5 turns of 28 AWG magnet wire on the source side and 7 turns center-tapped
on the load side.  That will work. 

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John
Kaufmann
Sent: Saturday, February 2, 2019 11:56 AM
To: topband@contesting.com
Subject: Re: Topband: Rx splinter

The BCC splitter design suggested by PC2A is based on the "magic tee"
splitter.  An excellent tutorial on magic tee splitters can be found on
W8JI's Web site:https://www.w8ji.com/combiner_and_splitters.htm.  These
splitters are very easy and inexpensive to build.  

A 1:2 splitter design using a single ferrite core can be found here:
http://michaelgellis.tripod.com/magict.html.  See Figure 7.  There is -3 dB
throughput from the source to each load port.  This splitter introduces a
180 degree phase shift between the two output ports but this is irrelevant
for splitting a receive antenna between two receivers.  I have built many of
these using Fair-Rite 2873000202 cores.  For a 50 ohm system, change the
37.5 ohm resistance to 25 ohms.  Use 7 turns (28 AWG magnet wire is
suggested) through the binocular core on the source side and 10 turns
center-tapped on the load side.  This will provide a 50-ohm input impedance
on all ports and excellent isolation (>25 dB) between the two load ports.

73, John W1FV



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Re: Topband: Rx splinter

[John Kaufmann]

The BCC splitter design suggested by PC2A is based on the "magic tee" splitter. 
 An excellent tutorial on magic tee splitters can be found on W8JI's Web site:  
  https://www.w8ji.com/combiner_and_splitters.htm.  These splitters are very 
easy and inexpensive to build.  

A 1:2 splitter design using a single ferrite core can be found here:  
http://michaelgellis.tripod.com/magict.html.  See Figure 7.  There is -3 dB 
throughput from the source to each load port.  This splitter introduces a 180 
degree phase shift between the two output ports but this is irrelevant for 
splitting a receive antenna between two receivers.  I have built many of these 
using Fair-Rite 2873000202 cores.  For a 50 ohm system, change the 37.5 ohm 
resistance to 25 ohms.  Use 7 turns (28 AWG magnet wire is suggested) through 
the binocular core on the source side and 10 turns center-tapped on the load 
side.  This will provide a 50-ohm input impedance on all ports and excellent 
isolation (>25 dB) between the two load ports.

73, John W1FV


-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Peter
Sent: Friday, February 1, 2019 4:29 PM
To: topband@contesting.com
Subject: Re: Topband: Rx splinter

Hi

May I throw up the BCC splitter?
http://www.bavarian-contest-club.de/projects/misc_projects/splitter.pdf

Peter
PC2A

9 circle RX array PCB's
https://www.pi4cc.nl/tech-info/rx-array/


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Re: Topband: capacity needed for Deturning tower

[John Kaufmann]

On 160 I've used a vertical wire of 20 feet with a 1000 pF variable
capacitor to detune a tower at its base.  You can scale that to 80.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of terry
burge
Sent: Friday, December 21, 2018 9:22 PM
To: topband@contesting.com; terry burge
Subject: Topband: capacity needed for Deturning tower

Hi again,


This may not be possible to answer with anything like 10% accuracy but can
someone give me an idea just how much capacitance I need for putting up a
50-55' vertical wire up the lower half of my tower to detune it on 75 meters
around the DX windown (3790-3800 Khz). The tower is Rohn 55 with 117' above
ground. A 3 element 20-6 mtr Steppir at 118', a GP6 at the very top with
peak at 134' and a 40 meter dipole (63' or so) at 104'. I have my K8UR style
4-Square around the tower with the lower half of the slopers pulled in
towards the tower. 


Since I've not been able to get a beverage or bog to work due to a lot of
noise I'm going to run a detuning line up to below my Comtek unit at 64' and
try detuning the tower. But I just don't know what to expect to need for
capacitance to detune the tower. 


Terry

KI7M

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Re: Topband: Detuning TX ant + QSK

[John Kaufmann]

The user's manual I wrote for the YCCC low-band receiving array contains a 
section on detuning antennas that are near the receiving array.  You can 
download the manual at:  
https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.pdf.
  (If the URL wraps because this text gets reformatted, be sure to copy the 
entire address).   See pages 46-48 of the manual.  Figure 39 on p. 47 shows a 
simple circuit that I use with my K3 for simultaneously keying my amplifier 
(AL-1200 with the QSK-5 option) and the vacuum relays (via a driver transistor) 
on my TX verticals.  The same circuit should work with other radios and 
amplifiers.  I used a simple 1N4001 back EMF diode in this circuit.  I'm not 
sure whether a "faster" diode would be better but this seems to work for me.  

The most important thing is to prevent hot-switching the vacuum relays by 
applying RF before the contacts close fully.  On my K3, I set the QSK delay to 
10 ms and I get excellent QSK operation with this setup.  The vacuum relays 
have held up just fine over 5 or 6 years of operation so I don't think 
hot-switching has been an issue.  

73, John W1FV


-Original Message- 
From: Richard (Rick) Karlquist
Sent: Wednesday, November 28, 2018 7:02 AM
To: jkaufm...@alum.mit.edu ; 'Jim Thomson' ; 'TopBand List'
Subject: Re: Topband: Detuning TX ant + QSK



On 11/28/2018 5:18 AM, John Kaufmann wrote:
> Jim,
>
> I use Gigavac GH-1 vacuum relays for detuning my TX antennas when 
> receiving.  The contact closure/release time is 6 msec.  You have to dial 
> in enough QSK delay in your radio so that you don't hot-switch the relays.
>
> 73, John W1FV
>

A quick note on the GH-1:

1.  In theory, there is no limit to speeding up closure.
OTOH, release can only be speeded up to the extent of collapsing
the magnetic field by omitting the usual reverse voltage
protection diode.  After that, the mechanical response
remains.

2.  This works neatly with the GH-1 being energized on
transmit, where you want the quickest response.

3.  The limiting factor to speeding up this model is
contact bounce.  You can only apply a modest amount
of speed up before you are limited by contact bounce.
With other models, of course, YMMV.

73
Rick N6RK 

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Re: Topband: Detuning TX ant + QSK

[John Kaufmann]

Jim,

I use Gigavac GH-1 vacuum relays for detuning my TX antennas when receiving.  
The contact closure/release time is 6 msec.  You have to dial in enough QSK 
delay in your radio so that you don't hot-switch the relays.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim Thomson
Sent: Wednesday, November 28, 2018 5:26 AM
To: TopBand List
Subject: Topband: Detuning TX ant + QSK

For you folks that have to de-tune your  TX ant,  so your dedicated  RX ant 
works correctly,
if you also operate qsk, how do you do it ?   Are you using a sped up vac  
relay to de-tune
the TX ant ?   I don’t see any other way to accomplish that task.  Or do you 
use vox cw ? 

Jim   VE7RF 
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Re: Topband: Vertical antennas aren't always best for DX

[John Kaufmann]

JC, 

You said: " Every dipole or inverted V irradiate  50% of the power
horizontal polarized broadside with the wire and 50% of the power vertical
polarized along the wire."  You cited EZNEC as evidence.

I am merely pointing out that as a general rule, this is not true.  The
issue *is* math because that is precisely how you determine the fraction of
power that goes into horizontal polarization and into vertical polarization.
As I pointed out, the relevant math is a 3-dimensional integration of the
radiation pattern in spherical coordinates.  

Take a dipole that is 1/4 wavelength high, which we can all agree is "low"
in wavelength terms.  At a takeoff angle of 90 degrees (straight up), EZNEC
shows that the horizontal and vertical components of radiation are about the
same.  It is easy to think there is a 50/50 split in horizontal/vertical
power because of this.  However, this neglects the radiation at lower angles
where the large majority of the radiated power is produced.  At a 45 degree
takeoff angle, the broadside horizontal power dominates the vertical power
by about 4 dB and the ratio increases at lower angles.  If the dipole is
higher than 1/4 wavelength, the ratio becomes even greater.

The math does not lie.

73, John W1FV



-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
n...@n4is.com
Sent: Tuesday, November 27, 2018 8:50 AM
To: jkaufm...@alum.mit.edu; topband@contesting.com
Subject: Re: Topband: Vertical antennas aren't always best for DX

John

 

The issue here is not math. It is the interaction of fields and matter. A
good text book is Electromagnetic waves and radiating system  by Edward C
Jordan and Keith G. Balmain. Chapter 9.

 

You can not ignore the close proximity with ground on 160m antennas for both
transmit signal and receiving signal. Too close it became more a
transmission line, getting high the irradiation increase and the maximum
horizontal power radiated or receiving signal intensity are near 1 ½ wave
high. The take off angle depends on the ground itself.

 

73’s

JC

N4IS

 

From: John Kaufmann  
Sent: Tuesday, November 27, 2018 8:16 AM
To: n...@n4is.com; topband@contesting.com
Subject: RE: Topband: Vertical antennas aren't always best for DX

 

In considering the *total power* radiated by any antenna, you need to look
at the 3-dimensional antenna pattern, not a 2-dimensional slice.  The total
radiated power is the 3-dimensional integration of the 3-dimensional
radiation pattern.  It is convenient to do this in spherical coordinates
because that is how we visualize 3-dimensional patterns.   In spherical
coordinates the integration applies the *smallest* weighting at elevation
angles around zenith.  Even if the dipole is low, the calculation shows that
the fraction of power that goes straight up is small compared to the total
radiated power.   This is easily understood in 3-dimensional spherical
coordinates:
https://www.khanacademy.org/math/multivariable-calculus/integrating-multivar
iable-functions/triple-integrals-a/a/triple-integrals-in-spherical-coordinat
es.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
n...@n4is.com <mailto:n...@n4is.com> 
Sent: Tuesday, November 27, 2018 6:58 AM
To: jkaufm...@alum.mit.edu <mailto:jkaufm...@alum.mit.edu> ;
topband@contesting.com <mailto:topband@contesting.com> 
Subject: Re: Topband: Vertical antennas aren't always best for DX

Sorry ,  but all antenna's on 160m are close to the ground and it is the

case, you can check by yourself using EZENEC if you don't know how to

calculate the fields.

There is no misleading here.

73

JC

N4IS

 

-Original Message-

From: Topband mailto:topband-boun...@contesting.com> > On Behalf Of John Kaufmann

Sent: Monday, November 26, 2018 8:53 PM

To: topband@contesting.com <mailto:topband@contesting.com> 

Subject: Re: Topband: Vertical antennas aren't always best for DX

The statement that the half of a horizontal dipole's radiation is vertically

polarized is misleading and needs qualification.  There is a vertically

polarized component off the ends of the dipole but it is only of consequence

at takeoff angles approaching 90 degrees, in other words straight overhead.

I would argue that these takeoff angles are of little interest for long

distance propagation.   

At takeoff angles lower than 60 degrees or so, the total radiation pattern

of a dipole at any reasonable height becomes dominated by the horizontally

polarized component that is broadside to the dipole.   The lower the angle

or the higher the dipole, the more insignificant the vertical component

becomes. This is all verifiable in EZNEC.  If this were not true, you would

not see the well-defined radiation patterns that are produced by HF Yagi's

at higher frequencies were the radiation is horizontally polarized for

virtually all signals of interest.

73, Jo

Re: Topband: Vertical antennas aren't always best for DX

[John Kaufmann]

In considering the *total power* radiated by any antenna, you need to look
at the 3-dimensional antenna pattern, not a 2-dimensional slice.  The total
radiated power is the 3-dimensional integration of the 3-dimensional
radiation pattern.  It is convenient to do this in spherical coordinates
because that is how we visualize 3-dimensional patterns.   In spherical
coordinates the integration applies the *smallest* weighting at elevation
angles around zenith.  Even if the dipole is low, the calculation shows that
the fraction of power that goes straight up is small compared to the total
radiated power.   This is easily understood in 3-dimensional spherical
coordinates:
https://www.khanacademy.org/math/multivariable-calculus/integrating-multivar
iable-functions/triple-integrals-a/a/triple-integrals-in-spherical-coordinat
es.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
n...@n4is.com
Sent: Tuesday, November 27, 2018 6:58 AM
To: jkaufm...@alum.mit.edu; topband@contesting.com
Subject: Re: Topband: Vertical antennas aren't always best for DX

Sorry ,  but all antenna's on 160m are close to the ground and it is the
case, you can check by yourself using EZENEC if you don't know how to
calculate the fields.

There is no misleading here.

73
JC
N4IS



-Original Message-
From: Topband  On Behalf Of John Kaufmann
Sent: Monday, November 26, 2018 8:53 PM
To: topband@contesting.com
Subject: Re: Topband: Vertical antennas aren't always best for DX

The statement that the half of a horizontal dipole's radiation is vertically
polarized is misleading and needs qualification.  There is a vertically
polarized component off the ends of the dipole but it is only of consequence
at takeoff angles approaching 90 degrees, in other words straight overhead.
I would argue that these takeoff angles are of little interest for long
distance propagation.   

At takeoff angles lower than 60 degrees or so, the total radiation pattern
of a dipole at any reasonable height becomes dominated by the horizontally
polarized component that is broadside to the dipole.   The lower the angle
or the higher the dipole, the more insignificant the vertical component
becomes. This is all verifiable in EZNEC.  If this were not true, you would
not see the well-defined radiation patterns that are produced by HF Yagi's
at higher frequencies were the radiation is horizontally polarized for
virtually all signals of interest.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
n...@n4is.com
Sent: Monday, November 26, 2018 11:06 AM
To: 'Roger Kennedy'; topband@contesting.com
Subject: Re: Topband: Vertical antennas aren't always best for DX

Roger

Every dipole or inverted V irradiate  50% of the power horizontal polarized
broadside with the wire and 50% of the power vertical polarized along the
wire. After the first refraction it does not matter. 

This is an electro-magnetic wave law. You can check that on EZENEC, it is
not a anecdote.


The advantage over vertical 1/4 wave antenna is efficiency.  The vertical
efficiency depends on the ground plane resistance, it is common to see
invert L with only 50 % irradiated power, the other 50% is dissipated on the
ground.

"In Theory, we know everything, but nothing works"

"In Practice, everything works, but we don't know why"

We never will fully understand the 160m band.

73's
JC
N4IS


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Re: Topband: Vertical antennas aren't always best for DX

[John Kaufmann]

The statement that the half of a horizontal dipole's radiation is vertically
polarized is misleading and needs qualification.  There is a vertically
polarized component off the ends of the dipole but it is only of consequence
at takeoff angles approaching 90 degrees, in other words straight overhead.
I would argue that these takeoff angles are of little interest for long
distance propagation.   

At takeoff angles lower than 60 degrees or so, the total radiation pattern
of a dipole at any reasonable height becomes dominated by the horizontally
polarized component that is broadside to the dipole.   The lower the angle
or the higher the dipole, the more insignificant the vertical component
becomes. This is all verifiable in EZNEC.  If this were not true, you would
not see the well-defined radiation patterns that are produced by HF Yagi's
at higher frequencies were the radiation is horizontally polarized for
virtually all signals of interest.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
n...@n4is.com
Sent: Monday, November 26, 2018 11:06 AM
To: 'Roger Kennedy'; topband@contesting.com
Subject: Re: Topband: Vertical antennas aren't always best for DX

Roger

Every dipole or inverted V irradiate  50% of the power horizontal polarized
broadside with the wire and 50% of the power vertical polarized along the
wire. After the first refraction it does not matter. 

This is an electro-magnetic wave law. You can check that on EZENEC, it is
not a anecdote.


The advantage over vertical 1/4 wave antenna is efficiency.  The vertical
efficiency depends on the ground plane resistance, it is common to see
invert L with only 50 % irradiated power, the other 50% is dissipated on the
ground.

"In Theory, we know everything, but nothing works"

"In Practice, everything works, but we don't know why"

We never will fully understand the 160m band.

73's
JC
N4IS


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Topband: Vertical vs. horizontal antennas at KC1XX

[John Kaufmann]

I would like to add some additional observations to the ongoing discussion
about horizontal vs. vertical antennas on 160.  At the KC1XX contest station
where I operate the low bands (160 and 80), we just installed two new
horizontal dipoles for 160.  For years, KC1XX has used a 3 element inline
vertical array that is described in an article I wrote back in 2002:
http://www.kc1xx.com/antennas/160_array.pdf.  (Note that my e-mail address
in that article is obsolete, so please use the e-mail address in this
message for any personal correspondence with me).  However, we have noticed
over the years that there have been times when the verticals don't seem to
be competitive, so we decided to try a horizontal antenna alternative to see
if that would help during those times.

 

I suspect the ground conductivity at the KC1XX location is not good, so that
needs to be considered in comparing antennas.  Vertical antennas suffer much
more over poor ground than horizontal antennas.  On 80m, KC1XX has
horizontally polarized delta loop arrays and a single vertical antenna that
is used for the "B" station on 80.  The vertical is always far inferior to
the delta loops, generally by 12-15 dB, which leads me to believe the ground
quality is pretty poor.  The delta loops have gain whereas the vertical does
not, but that alone does not explain the big difference between antennas.

 

The new 160 dipoles, installed just in the past 2-3 weeks, are very high.
One is broadside NE/SW and the other SE/NW, both with the apex at 200 feet.
The ends of the NE/SW dipole are at about 160 feet and the ends of the SE/NW
dipole are 130-140 feet.  KC1XX has a hilltop location with steep terrain
drop-off in multiple directions, particularly in the sector between
northeast and south.  To the east for example, the average downsloping
gradient is about 10% for the first 2000 feet and it continues down at a
somewhat shallower gradient for several thousand more feet.  As a result,
terrain modeling with the HFTA program shows a very large enhancement in the
dipole low-angle radiation, from 0 to 10 degrees, that is easily competitive
with a vertical array.  However, I don't have any data to know how useful
those very low angles are on 160.

 

The dipoles are high enough that they do exhibit significant directivity.
DX signals drop off a lot off the ends of the dipoles as you would expect. 

 

In the CQWW contest this past weekend, I spent a fair amount of time on 160
on both days and got to compare the vertical and horizontal antennas on many
DX stations.  Neither system was superior all of the time.  If I had to
generalize, which is a bit risky based on just two days of observation, I
would say that the vertical array is better, sometimes much better, on
average.  However, it varies greatly in specific situations.

 

When the band first opens to Europe before local sunset, the dipoles are
typically much better but that difference quickly diminishes after dark.
The first night in CQWW, the vertical array was generally 10-15 dB better
into Europe throughout the night but the second night it was almost a
toss-up where it was hard to see much difference between horizontal and
vertical.   Sometimes the dipole would be a bit better on a few stations and
other times the verticals had a slight advantage.

 

To the Caribbean, the dipole and verticals were roughly comparable, although
on some stations one antenna could be as much as 10 dB better than the other
for short periods of time.  Deeper into South America, the verticals were
usually better and it was generally the same on the few African stations I
heard. 

 

We worked a couple JA's, a UA0, and some VK's.  The verticals were superior
for those contacts.

 

What was very interesting was that sometimes I observed a long, slow QSB
where signals would start to drop down on the verticals while coming up at
the same time on the dipoles.  I suspect this is a polarization effect
rather than angle-of arrival because the dipoles and verticals both have
significant low-angle response where I would not expect one to outshine the
other if polarization were not a consideration.  This leads me to think that
feeding both horizontal and vertical antennas simultaneously through a
splitter might be a good option to have some of the time.

 

In summary, if I had to pick only one antenna system it would be the
verticals.  However, the high dipoles can easily hold their own at times and
it is good to have both options now.

 

73, John W1FV

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Re: Topband: YCCC op amp preamp...

[John Kaufmann]

You can find a schematic on p.54 of the user's manual which can be download
from the DXE Web site:
https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.
pdf.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Peter
Bertini
Sent: Tuesday, November 13, 2018 5:35 PM
To: topband@contesting.com
Subject: Topband: YCCC op amp preamp...

Is there a schematic available online for the YCCC preamp?  I see DX
Engineering is long sold out of kits and I'd like to try dead bugging a few
amplifiers to play with.

Pete
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Re: Topband: Which compromise receiving antenna

[John Kaufmann]

I designed the YCCC preamp so I can answer the question about the AD8055 op
amp.

As used in the YCCC preamp, the linearity is actually very good.  We use a
YCCC receiving array at KC1XX in a multi-operator, multi-transmitter
environment with 20 foot receive verticals.  That's a pretty severe RFI
environment.  When listening on the array on either 160m or 80m, there is
absolutely zero interference or other noticeable degradations from
out-of-band transmitters.  When listening with an in-band transmitter, there
is a lot of noise near the transmitter frequency, but most of it is phase
noise from the transmitter itself.

If you want more technical detail, here are some of the considerations
behind the choice of the AD8055.  First of all, the YCCC preamp is a kit.
Based on that consideration, I ruled out surface mount op amps that
inexperienced kit builders might not be comfortable with.  In truth there
are some truly outstanding surface mount parts with much better performance.
The AD8055 comes in a standard 8-pin DIP package that's easier to work with
and it was the best 8-pin DIP part I could find.  It is intended
specifically for use in RF systems.

Second, the preamps must exhibit very accurate gain and phase matching to be
used in a multi-element active array.  The YCCC preamp meets this
requirement because it operates with unity voltage gain in a negative
feedback configuration that virtually guarantees extremely accurate gain
setting.   There is no trim adjustment needed at all for gain.  I have done
VNA measurements on many of these preamps built by different people and
every single one of them, when assembled correctly, exhibits a gain accuracy
of +/-0.1 dB gain and better than one degree of phase matching accuracy
across 160 and 80.  The large amount of negative feedback used at unity gain
also contributes directly to low distortion.

I don't have test equipment to perform accurate distortion measurements.
However, the AD8055 datasheet does have data on second and third order
harmonic distortion figures that look very good at 1.8 through 4 MHz.  In
fact these distortion levels are similar to what you might see in a high
quality stereo audio amplifier.

Having said all that, prospective system builders should be aware that DX
Engineering has just discontinued sales of the YCCC preamps as the entire
inventory of these kits has been sold out.  Once their inventory of phase
combiner and direction switch kits is sold out, those will also be
discontinued.  YCCC, as a club, has no intention of selling kits.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Richard
(Rick) Karlquist
Sent: Tuesday, November 6, 2018 3:17 PM
To: donov...@starpower.net; topband reflector
Subject: Re: Topband: Which compromise receiving antenna


I am puzzled by the choice of the AD8055 for the amplifier.
It seems to be unprepared for strong BCB signals.  Has
anyone successfully used this near a BCB station?  I am
6 miles from a 50 kW station.  It seems to me there are
much better amplifiers available.  Or why not a FET follower?

Rick N6RK
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Re: Topband: Working LP from VK6 to the USA - season approaches

[John Kaufmann]

I was one of the lucky ones to work VK6VZ on LP last November 7.   I got him at 
2128Z with signals peaking from the east.  It was exactly at my sunset.  I was 
followed by two other W1 stations before the opening ran out.  Good luck to all 
on this one!  

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Steve Ireland
Sent: Thursday, November 1, 2018 12:19 AM
To: Mark K3MSB
Cc: Topband reflector
Subject: Re: Topband: Working LP from VK6 to the USA - season approaches

Hi Mark

Great to hear from you - will definitely be looking for you. This week I've 
been chasing Z23MD (without luck so far), but done the odd CQ on 1831.5 after 
SR - my SR is currently about 2120Z..

The first couple of weeks in November is usually the best time for LP – and, as 
Roger N1RJ has pointed out, if you look at the midpoint between (after) my 
sunrise time and (before) your sunset time, this is when signals generally 
peak.  The openings usually last for two to five minutes at best, but signal 
strengths can be strong – last year on 7 November I worked several east coast 
NA stations LP with strengths peaking S7.

Vy 73

Steve, VK6VZ


From: Mark K3MSB 
Sent: Thursday, November 01, 2018 3:25 AM
To: vk...@arach.net.au 
Cc: topBand List ; k...@myfairpoint.net 
Subject: Re: Topband: Working LP from VK6 to the USA - season approaches

Hi Steve

I'd be delighted to take a crack at working you.


Last April Phil VK6GX heard my CQ and answered me,  but I was unable to hear 
him.   I was beating my head against the table,  and for some added salt in the 
womb...N0FW was telling me "Mark, he's answering you".Argh!   The RBOGS 
just didn't do that job that time!

Today was a gorgeous fall day here in southeastern PA and what better way to 
spend it than by installing a HI-Z 3 in the back yard!The mounts and 
antennas are "planted" and look great (though my wife may not quite agree).
The electronics box will have to wait until the final mowing of the yard, and I 
hope that will be tomorrow.

With business constraints,  I'm targeting Nov 10th to have the HI-Z 3 on the 
air and all radials run for the INV-L.

That's the plan and we all know how plans go

73 Mark K3MSB









On Tue, Oct 30, 2018 at 10:02 PM Steve Ireland  wrote:

  G’day

  After retiring earlier this year, I’ve managed to retrain (at least 
temporarily) my body to get up at 5am again for the pre-sunrise period here 
during November. 

  When not chasing DX to boost my DXCC total, I’ll spend time CQing on 1831.5, 
particularly in the 15 to 20 minute period after sunrise, looking first for 
EU/Africa and then North America long path.  

  I know there a number of east coast USA stations for who it is easier to work 
VK6/Zone 29 long path rather than trying for a contact at their sunset.

  Vy 73

  Steve, VK6VZ

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Re: Topband: elevated radials

[John Kaufmann]

When you are using just a single vertical, some pattern skew is probably 
acceptable.  However, at KC1XX we are using several verticals in an array and 
nonideal radiation from the individual verticals degrades the directive pattern 
that we are trying to achieve.

73, John W1FV

-Original Message-
From: Grant Saviers [mailto:gran...@pacbell.net] 
Sent: Monday, October 22, 2018 11:38 AM
To: jkaufm...@alum.mit.edu; Topband@contesting.com
Subject: Re: Topband: elevated radials

I have a 160m T with 8 elevated 125' radials and the currents are worst 
case 3:1 unequal for various reasons (nearby steel building & towers).  
I've modeled this with EZNEC Pro4 by placing the actual radial currents 
as sources in each radial.  Obviously the sum of those currents must 
equal the vertical current and those measurements agree.

I'm wondering what is your "radials generate unwanted radiation".  The 
modeling shows the pattern is less than 1 db "out of round" with my 
unbalanced currents.

I know there are many comments that radial currents must be equalized.  
My own DXpedition experience with single radial SteppIR CrankIRs and 
modeling them shows only a 2 or 3 of db "out of round".Some other 
modeling I did showed small pattern skew even with 3 or 4 radials removed.

So what am I missing?

Grant KZ1W

On 10/21/2018 15:22 PM, John Kaufmann wrote:
> We just went through the exercise of tuning up the elevated radials on the
> KC1XX 160m vertical array in advance of the upcoming CQWW DX Contests.
>
> The first thing is to make each of the radials look as electrically
> identical as possible.  We assume the length of the vertical element is
> fixed and not adjustable.  We start by connecting one radial at a time to
> the feedpoint of the vertical and measuring the impedance at the vertical
> feedpoint.  In general the impedances will not be exactly the same.  With
> unequal impedances, the currents flowing in each of the radials will
> generally be unequal, which is undesirable because then the radials generate
> unwanted radiation.   Suppressing that radiation depends on making the
> radial currents as close to equal as possible so that in the far field, the
> radiation from each radial is cancelled by the out-of-phase radiation from
> an opposing radial.  The lengths of each of the radials then need to be
> adjusted to equalize the feedpoint impedances of the vertical with one
> radial at a time.
>
> We trimmed the radial lengths to make the feedpoint reactance X=0 at the
> desired resonant frequency of the vertical.  (Note that if there are other
> vertical elements present in an array, they have to be detuned to insure
> they do not corrupt the measurement.)  However when we did this, we found
> that the resistance (R) at the feedpoint was different with each individual
> radial and it was not possible to equalize the resistances and reactances
> simultaneously.   Apparently this is because of the non-homogeneous
> environment (ground and surrounding trees) around each radial.  So, we do
> the best we can in equalizing the impedances and accept some degree of
> imperfection.  The more radials present around the vertical, the more
> forgiving the system is of imperfections in radial symmetry.
>
> As a final check we then connect all of the radials to the vertical element
> and check the impedance again.  The resonance (where the reactance X=0)
> should be close to the resonance that was obtained in the radial trimming
> exercise for the vertical with one radial at a time.
>
> 73, John W1FV
>
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Re: Topband: elevated radials

[John Kaufmann]

We just went through the exercise of tuning up the elevated radials on the
KC1XX 160m vertical array in advance of the upcoming CQWW DX Contests.

The first thing is to make each of the radials look as electrically
identical as possible.  We assume the length of the vertical element is
fixed and not adjustable.  We start by connecting one radial at a time to
the feedpoint of the vertical and measuring the impedance at the vertical
feedpoint.  In general the impedances will not be exactly the same.  With
unequal impedances, the currents flowing in each of the radials will
generally be unequal, which is undesirable because then the radials generate
unwanted radiation.   Suppressing that radiation depends on making the
radial currents as close to equal as possible so that in the far field, the
radiation from each radial is cancelled by the out-of-phase radiation from
an opposing radial.  The lengths of each of the radials then need to be
adjusted to equalize the feedpoint impedances of the vertical with one
radial at a time.

We trimmed the radial lengths to make the feedpoint reactance X=0 at the
desired resonant frequency of the vertical.  (Note that if there are other
vertical elements present in an array, they have to be detuned to insure
they do not corrupt the measurement.)  However when we did this, we found
that the resistance (R) at the feedpoint was different with each individual
radial and it was not possible to equalize the resistances and reactances
simultaneously.   Apparently this is because of the non-homogeneous
environment (ground and surrounding trees) around each radial.  So, we do
the best we can in equalizing the impedances and accept some degree of
imperfection.  The more radials present around the vertical, the more
forgiving the system is of imperfections in radial symmetry.  

As a final check we then connect all of the radials to the vertical element
and check the impedance again.  The resonance (where the reactance X=0)
should be close to the resonance that was obtained in the radial trimming
exercise for the vertical with one radial at a time.  

73, John W1FV

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Re: Topband: How to determine impedance

[John Kaufmann]

Here's another method that's based on the engineering textbook transmission
line equation and use of an impedance analyzer to make an impedance
measurement.

You can look up the transmission line equation on Wikipedia:
https://en.wikipedia.org/wiki/Transmission_line.  Scroll down the page to
the paragraph with the title "Input impedance of lossless transmission
line".This equation gives the impedance Zin looking into a transmission
line in terms of the line's characteristic impedance (Zo), the load
impedance (ZL) at the far end, and the electrical length of the transmission
line.

If electrical length of the line is 1/8-wavelength (lambda/8), you terminate
the line in a short circuit (ZL=0), and you solve for Zin, you find:  
Zin=jZo or Zo=-jZin.  Everything drops out of the transmission line equation
except for the characteristic impedance Zo that you are trying to find!
(Homework assignment for you mathematicians:   Terminate the line in an open
circuit (ZL=infinity) and solve for Zin in terms of Zo for the same 1/8-wave
line).

Now you need to set up a measurement with your analyzer that duplicates
these conditions.

Terminating the line in a short circuit is the easy part.  Next you have to
determine the frequency where the line is 1/8-wave long.  How do you do
this?  First use your impedance analyzer to find the frequency where the
line is a 1/4-wave long (if the line is terminated in an open circuit at the
far end, the input impedance goes to zero at the lowest frequency where the
line is a 1/4-wave long).   Divide that frequency by 2 and you have the
frequency where the line is 1/8-wave long.  Now tune your analyzer to that
frequency and measure the input impedance Zin to the line.  In general
Zin=R+jX.  For an ideal line, that impedance is purely imaginary, i.e. R=0
and X is some finite number.  If your analyzer gives you some small R value
that is not zero, ignore it and work with the just the X value.  You now
have Zo=-X as derived above.  You're done.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Martin
Sent: Wednesday, January 24, 2018 6:28 AM
To: topBand List
Subject: Topband: How to determine impedance

Topbanders,
for the construction of the beverage ( a 2 wire reversible beverage, that
is) from my post a few days ago i wanted to know how to measure or determine
the impedance of the open wire. I stumbled across a very simple method some
of of you might know , some might not. Anyway, here is the method. It works
for coaxial cable or open wire.
You need no fancy measurement gear-  rule, pocket calculator and LC meter
will do. For really long runs you might need the help of a tape rule or even
google maps.

Measure the length of the unknown coaxial cable or open wire (DUT Device
under test) in meters m.

With both ends open, measure capacitance C of DUT, divide it by it's length
( C' = C/m) .

Shorten one end, measure inductance of DUT, divide it by length ( L' =
L/m) .

Now calculate

Z= 1000 * squareroot(L'/C')

Voila.

It may also help to determine if and where your cable or 2 wire beverage has
an intermittance when you already know it's impedance it had before the
failure. Transform the formula accordingly.
I think it should also help to determine the impedance of the beverage (
single wire or 2 wire) measured against ground(?).


-- 

Ohne CW ist es nur CB..

73, Martin DM4iM
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Re: Topband: Big 160m openings just before K index spikes

[John Kaufmann]

I have also observed enhanced, and sometimes extraordinary, propagation at the 
onset of disturbed conditions.  A recent notable example was the LP QSO with 
VK6VZ that I reported last month:  
http://lists.contesting.com/pipermail/topband/2017-November/052869.html.  At 
the time of the QSO, the K index was 6. 

However, disturbed conditions do not always bring enhanced propagation.  There 
is not a 1:1 correlation in my experience but it's worth checking the band when 
severe geomagnetic conditions are imminent

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of George Taft 
via Topband
Sent: Friday, December 8, 2017 9:29 AM
To: Bob Lawson N6RW; topband@contesting.com
Subject: Re: Topband: Big 160m openings just before K index spikes

Hi Bob
Do agree with your observations relative to prop enhancement on the upside 
(beginning) of solar disturbances.  Especially for we northern types close to 
the northern auroral zone.
I've made some extraordinary contacts in my 35years on topband during these 
situations.
Now if we could just have one fall on the days that stns like XW4ZW and the 
BD/BG  stns are active, hi/
73  George  W8UVZ 

On Wednesday, December 6, 2017 6:09 PM, Bob Lawson N6RW  
wrote:
 

 Is it just my imagination or have others noticed big 160 meter openings
- hours before big K index spikes?

It seems that several times, we have had big openings into Europe and Asia from 
out here in Arizona and my hopes of having a great opening the next night was 
ruined by a big geomagnetic storm. Last Saturday morning, the JAs were quite 
weak here.  Sunday morning, several Asians had good signals.  BD4WN was the 
loudest I'd ever heard him and JA3YBK was 10 over 9 at sunrise until 15 minutes 
past sunrise.  He was still solid 45 minutes after sunrise.  Sunday night, I 
heard the first EU Russian since getting on TB almost three years ago.  I was 
looking forward to a great post-contest Monday night and bang - the K index 
jumped up to 4 - just like a few weeks before.  I heard no Asian signals this 
morning and so far no EU on 160 tonight (Monday night).

73 all de Bob N6RW Prescott AZ

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Re: Topband: Good long path opening from VK6 to NA

[John Kaufmann]

It was certainly a great opening between VK6 and my QTH (at W1FV).  As Steve
indicated, we had been trying to make a LP QSO for a number of years.  In
the past I had heard him a few times but it was marginal and we were never
able to connect for a two-way.  This time it was easy. 

Steve's e-mail indicates his SR was 2114Z.  My sunset was 2130Z, so based on
SS/SR times there was no common darkness between Steve and myself.  In fact,
I'm not sure there is much, if any, common darkness between VK6 and W1 at
any time of year to make LP QSO's, so that helps explain why this path is
not a common occurrence on 160, even though it does occur regularly on 80.
It's even more difficult for other parts of the USA because at this time of
year, W1 land has the earliest sunsets in the country.   I continued to copy
Steve for about 15 minutes after our QSO, meaning the opening lasted about
30 minutes past Steve's SR.  

73, John W1FV

 

 

-Original Message-
From: Steve Ireland <  vk...@arach.net.au>
To: Topband reflector < 
topband@contesting.com>
Cc: Phil Hartwell <  vk...@yahoo.com>
Sent: Wed, Nov 8, 2017 2:52 am
Subject: Topband: Good long path opening from VK6 to NA

G'day It has been a pretty poor season here so far, with conditions after
VK6 sunset into North America at/before sunrise well down on last year.
However, this morning the band opened well into eastern North America. Jeff
VY2ZM was 569 at 2100Z (14 minutes before sunrise here) peaking a couple of
minutes after my sunrise at 599, during our QSO. After a internet message
from John W1FV (MA) to try for a QSO, we worked easily - after a number of
years of trying - at 2127Z with reports of 559 both ways. At the end of the
QSO John peaked 589 and I was then QSOed by Roger N1RJ (ME) 56-79 and Dick
W1ZC (NH) 579. Long path QSOs with the USA on 160m only occur rarely from
here - I've had about 15 in 22 years - but really get the adrenaline going
when they occur. This was a really good opening - and the A Index was 32 and
the K index 6. What a strange band is the topband! Vy 73 Steve, VK6VZ ---
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Re: Topband: Good Conditions Last Night

[John Kaufmann]

Another sign of things looking up on Topband:  I worked VK6VZ on long path
at 2128Z today, right at my sunset.  Steve peaked 569 from the ENE and he
also worked at least a couple other W1's.  I also had partial copy on VK6LW
CQing around the same time but Kevin was right at the noise and not quite
strong enough to make an attempt at a QSO.

73, John W1FV

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Re: Topband: Relay switching at the base on antenna

[John Kaufmann]

I use the "Key Out" line of my K3S to drive the base of a homebrew
transistor switch that, in turn, drives a relay coil at the base of my
antenna. There is an isolation diode between the K3S keying line and the
switching transistor because I also use the same keying line to switch my
AL-1200 QSK amp.   I run full QSK with a Gigavac GH-1 vacuum relay as the
switching relay at the antenna.  I set the QSK delay in the K3S to 10 ms and
the GH-1 has a closure time of 6 ms.  It works fine.  I've never had an
issue with hot switching in full QSK.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James
Wolf
Sent: Saturday, September 23, 2017 8:08 PM
To: 'Richard (Rick) Karlquist'; 'MR TREVOR DUNNE'; topband@contesting.com
Subject: Re: Topband: Relay switching at the base on antenna

Trevor,

I suspect you may be trying to detune the tower during receive, which I plan
on doing here as well.
Check your transceiver Amplifier Key Output line.  That line should close
about 10ms before any RF output from the radio occurs, for the very reason
Rick mentions below.

Any suggestions for the group on which relay to use for this?  I don't want
to give up my QSK.

Jim - KR9U
---
>There is nothing simple about this, because you need to avoid hot
switching.  This means that you need to start with the rig signal that is
intended for use with QSK linears.  This signal will change to the transmit
state 10 ms before the transmitter actually starts putting out RF.  The name
of this signal will vary depending on the rig, and the "PTT" signal may or
may not be the correct one.  Additionally, in some rigs you may need to put
a switch in the QSK position (such as the FT1000).

>Once you have a 10 ms head start, you need a relay that will close in 
>less
than 10 ms.  If necessary, you can use speed up circuits that put a
temporary overvoltage on the coil of the relay.  This requires that the
relay is energized on TX and non-energized on RX, rather than vice versa.

>In keeping with the word "simple":  a piece of hook up wire running to 
>the
base of the antenna is much simpler than trying to send DC on the coax,
depending on how hard it would be to install this wire.  You can still use
the shield of the coax as the return connection.

>Rick N6RK

On 9/23/2017 5:39 AM, MR TREVOR DUNNE wrote:
>> Hi All
> 
> >Can Anyone tell me a simple way to switch a 12v relay at the base of 
> >an
antenna using the rigs ptt as the trigger??


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Re: Topband: greyline prop forecast

[John Kaufmann]

What Frank says (below) is 100% correct.  There is simply no substitute for
time in the chair.  I never use any propagation prediction methods.  I know
from more than three decades of lowband DXing and contesting experience when
the openings are most likely to occur but I can't predict them in advance.
Often the openings last only a few minutes, so timing is everything.

There are seasonal trends that favor greyline LP propagation during certain
months, but there is no way to predict on a day-to-day basis when it will
happen.  For example, from my New England QTH, greyline openings to JA can
occur on 80m during Nov., Dec., and Jan. (and sometimes Feb.), just after
our sunset, but there are only a small handful of days that I would
characterize as "good" days where you don't need a world-class station to
make the grade.  Even more rarely, the greyline will bring in other parts of
Asia, like UA0, BY, 9M2, etc., around the same time as JA.  I was one of the
fortunate ones to work XX9D earlier this week on 80.  I had just turned on
the radio right after my sunset and caught him CQing.  It was a day of
highly exceptional greyline propagation, which made it  possible to work XX9
through the Eu wall.

On 160, greyline LP openings in W1 land are far more rare than on 80.  I
have heard long path JA's on Top Band no more than half a dozen times in 30
years, but have never been able to work one.  However, I have been able to
work VK6, 9M2, and JT via greyline LP on 160 but it happens maybe once a
decade.  You simply have to be there when it happens.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
donov...@starpower.net
Sent: Friday, February 17, 2017 10:44 AM
To: topband@contesting.com
Subject: Re: Topband: greyline prop forecast

Hi Kris, 


There's no substitute for butt in chair time if you want to work grey line
long path DX on 80 meters. 160 meters is also possible, but much more
difficult. 


Just check your local sunrise/sunset times and the sunrise/sunset times in
your target area and sit your butt in your chair especially during the 30
minutes leading up to sunrise at the eastern end of the path. 


While we've been discussing this topic, at least half a dozen east coast USA
80 meter DXers worked XX9D on the 80 meter greyline longpath at about 2300Z
and none of us were aided by forecasts. 
Imagine that... 



I know of no 80 meter DXer who has achieved greyline long path success
through forecasts, nor do we know of any technical breakthroughs on the
horizon that will change this in the foreseeable future. 


73
Frank
W3LPL 


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Re: Topband: Cutting Delay Lines

[John Kaufmann]

In principle, any *odd* multiple of 4.118 MHz (the frequency where the cable
is 1/4 wavelengths long) will work when the far end of the cable is
open-circuited.  If you short-circuit the far end of the cable, then look
for X=0 at *even* multiples of 4.118 MHz.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Ed
Stallman
Sent: Tuesday, July 12, 2016 11:05 PM
To: Topband
Subject: Topband: Cutting Delay Lines

I'm cutting a 40 degree and a 20 Degree Delay line using RG6 at 1.83MHz for
a  receive 8 circle array ! I know the velocity factor of the RG6 and have
all the math worked out .

After doing the calculations and trimming the RG6 back , I'm looking for
X=0 at 4.118 MHZ ( or as close to X=0 as possible )

Now to my question: I'm finding the X=0 to be a broad range , looks to be +
- 50 KHz on my MFJ 259b .. I know , I need a better analyzer ... 
Can I double of quadruple the frequency to narrow the span where X=0?

Thanks Ed N5DG



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Re: Topband: low band propagation at solar min

[John Kaufmann]

(Note: disregard my earlier incomplete post) 

Carl K9LA:  " But in my opinion (and in the opinion of others) the deep and
long solar minimum between Cycles 23 and 24 (2006-2010) didn't live up to
this axiom compared to the not-so-deep and not-so-long solar minimum between
Cycles 22 and 23 (1995-1997). It suggests that all solar minimums aren't the
same."

I will continue the comparison by saying that the solar minimum in the
mid-1980's topped that of the following two decades in terms of low band
propagation.  Top Band activity in the 1980's was nothing like it is today,
but despite that I observed many openings into Europe that sounded like a
20m opening.  Propagation to mid-eastern and central Asia occurred pretty
regularly.  I remember hearing 9M2AX on long path much louder than most of
the Europeans he was working.  JA's were almost a daily occurrence into W1
during January of 1987.  

I assumed that this was normal propagation for 160 but I have never observed
anything consistently as good as it was in the 1980's.  Anyone else found
this to be true?  What was different about the solar minimum in that decade?

73, John W1FV



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Re: Topband: low band propagation at solar min

[John Kaufmann]

> As for low band propagation being better at solar min, I grew up believing
in this axiom. But in my opinion (and in the opinion of others) the deep and
long solar minimum between Cycles 23 and 24 (2006-2010) didn't live up to
this axiom compared to the not-so-deep and not-so-long solar minimum between
Cycles 22 and 23 (1995-1997). It suggests that all solar minimums aren't the
same. Perhaps a deep and long solar minimum is not good for the low bands
(and there is a physical reason for this). Again, we'll just have to wait
and see what happens.




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Topband: Strange 160m intruder

[John Kaufmann]

I have been observing an intruder whose behavior is unlike anything I have
seen before.  It consists of a comb spectrum of CW tones in the 160m band.
They pulse on and off at a regular interval.  There is never any form of
identification transmitted by it.

 

Thanks to my Elecraft P3 panadapter, I have determined that this intruder is
actually composed of two distinct sets of tones that are synchronized.  I
have posted a YouTube video of the P3 display here:
https://www.youtube.com/watch?v=-OaA1CBH_Xk.

 

In the video you can see the display is centered on one tone at 1822.9 kHz,
and it is synchronized with other tones spaced approximately, but not
exactly, every 50 kHz.  They all pulse on and off together.

 

The second set of tones pulses on when the first set pulses off, and vice
versa.  These tones are spaced about midway between the tones in the first
set.

 

>From my QTH in eastern MA, the direction of arrival is WSW and I can hear it
all night and all day.  The signals are very steady with no QSB, so it must
be something within groundwave distance of me.

 

A few months ago, I posted a report of a similar intruder on 1814 kHz.  I
never determined what that was, and nobody else could hear it.  That one has
disappeared but perhaps this new one is related to it, because the direction
of arrival is the same.  Also both are about the same strength and audible
24 hours a day.

 

Does anyone recognize what kind of intruder this might be?

 

73, John W1FV

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Re: Topband: 2 element vertical for 80m with 1/8wavelength spacing

[John Kaufmann]

I also use a vertical phased array with 1/8-wave spacing on 80m.  I did this 
because of limited space.  Like PE5T describes in his post below, I used the 
method in ON4UN's book and originally described in a series of articles by K2BT 
in Ham Radio magazine (no longer in publication) in the 1980's.  I designed my 
own custom L-C circuits for phasing and matching.  I don't think there is a 
simple plug-and-play solution that would provide good performance at close 
spacing like this.

As Kees says, the impedances at close spacing are low and you have to work at 
keeping losses small.  Otherwise you don't realize the theoretical gain.  This 
means a large radial system.  I use over 100 radials per element.   The 
theoretical gain of my system is about 4 dB.  This is about what I see in 
practice comparing my 2-element array to a single reference vertical.  My array 
is optimized for the low end of the 80m CW band and I get up to 25 dB F/B.  I 
still see some F/B as high as 3700 kHz but by 3800 kHz it is omnidirectional.  
The SWR is close to 1:1 at 3500 kHz but goes up to 2:1 around 3550 kHz.

I use a separate network optimized for 3800 kHz for SSB, but 98% of my 
operation is CW.

The system does work very well provided you have a good ground system.  I have 
worked 333 countries on 80m with this system from an average suburban location.

I also retune this system for 160m operation, but that is another story.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Kees Nijdam
Sent: Tuesday, April 19, 2016 12:07 PM
To: Filipe Lopes; topband
Subject: Re: Topband: 2 element vertical for 80m with 1/8wavelength spacing

Hello Filipe,

Yes, I have such a system.
Cost me several days to optimize it.
My comments.
The 2x157 and 39 degrees phasing lines are based on very good earth systems
(2-3 Ohm). When your radial network is 5 Ohms, it is a different story. That is 
because the driving impedances are very low (in my case 19,27+j21,14 Ohms and 
13,86-j15,73 Ohms) and the influence of the earth system on these impedances is 
big (a 1/4 lambda system is not that critical) If you do not know the 
impedances of your verticals, the only way to go forward is to measure the self 
impedances and the coupled impedances. After that you can follow the calc 
ulations in ON4UN's book and software.

My system is optimized for 3510 kHz and with a signal source at 400 meters I 
found a front to back ratio of 24 dB for this frequency.
On 3500/3520 kHz is was  20 dB, on 3540 kHz only 10 dB and higher in frequency  
the antenna becomes more and more omni directional.
However, the swr was OK over the whole band, also on 3800 kHz.
So it can be used on 3800 kHz but without directivity.

You need a very good radial system and to decide for CW or SSB . My advice: 
better and less critical is to increase the distance between the verticals with 
a few meters.

Is it worth the effort? Yes I think so. I have one vertical permanent and 
during the winter I install the other. The few dB extra gain is good but I was 
also very happy with the system as RX antenna. I have it oriented north-south 
and it is nice to hear KH6AT over the south pole and not over the north pole..

Kees, PE5T

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Re: Topband: Strange propagation

[John Kaufmann]

I was lucky enough to visit W1BB in person back in the early 1970's.  I got
to see his home station and the famous water tower station.  As I recall the
two stations were a bit further apart than walking distance, unless you
didn't mind walking a lot.  We drove there from his home.

I'm almost certain that all of his serious DXing was done from the water
tower location.  He also had a 160m station at his home, but it was on a
very small urban lot and as I recall, he had only a low dipole up for 160m
there.

Whenever I heard him operating from the water tower site, he would sign
W1BB/1 to indicate portable operation but I guess that was required back
then.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
mstang...@comcast.net
Sent: Friday, January 15, 2016 3:42 PM
To: Herbert Schoenbohm; topband@contesting.com
Subject: Re: Topband: Strange propagation


You could look at this in another way. 

Wasn't W!BB's location a the Water Tower an early form of RHR, except that
he walked to the remote site instead of operating remotely.

Does anyone know if Stew made his DXCC solely from the Water tower site?

Did anyone else ever operate from the Water tower site?

Mike N2MS



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Topband: Update on 1814 kHz mystery signal

[John Kaufmann]

I received a number of replies on the subject of the mystery CW/QRSS signal
that I've been hearing every day on 1814.0 kHz. It's strong at my QTH just
west of Boston.   Most people don't hear it and some do hear something but I
don't think it's what I am hearing.

 

Here is some additional info.  I hear the signal every morning from ~1100Z
through sunrise (currently ~1215Z), after which I shut down.  The other
morning HL5IVL was on 1814 but that frequency was totally blocked for me by
this signal.   I do not hear it during the first part of the evening from
sunset through about ~0300Z.  This pattern repeats every single day.

 

I am beginning to think the source is indeed within groundwave range of me.
This is because I see very little QSB on the signal when it is there.  I
hear it on several different antennas, include two amplified systems with
short verticals, my TX vertical (not amplified), and a low horizontal
dipole.  Interestingly it's far weaker on the dipole than the vertical
antennas, maybe because the low dipole has poor groundwave response.

 

If there are folks in the New England area, particularly MA, CT, or RI,
please take a listen if you are able.  This would help me determine how
local the problem is to me.

 

73, John W1FV

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Re: Topband: 4SQ vs. 8 circle rcv

[John Kaufmann]

Based on the RDF metric, which is a very useful way of comparing antennas,
the differences between the "best" arrays is not that great--maybe 1 to 2
dB.  I have used Beverages and a number of different receiving arrays, and
found that in practice it is very hard to discern 1 dB RDF differences
between antennas.  So yes, in a sense, there is not a huge difference
between the published numbers for the 4 square and 8 circle.

However, there are other things to consider here.  When the RDF gets large,
say more than 12-13 dB, the beamwidths get very narrow.  This means that the
angular footprint over which the high RDF is actually realized is quite
small.  Once you are outside the "sweet spot", performance falls off pretty
sharply.  Unless you can somehow rotate the beam footprint in fine steps,
like a rotary Yagi, you will have gaps where the large RDF actually doesn't
help you and you may do worse than with a lower RDF antenna with a wider
beam footprint.

The other point is that RDF is a good predictor of receiving performance
only to the extent that external atmospheric noise is more or less uniformly
distributed over the entire receiving hemisphere of solid angles.  When
noise is stronger in one particular direction, then RDF is less accurate at
predicting performance.  When you beam in a direction of high noise, you
just pick up more noise and you won't see the theoretical advantage of RDF.
I observe this every morning when I beam SW, where the ambient noise level
jumps up typically 5-6 dB  compared to other directions.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike
Waters
Sent: Wednesday, January 13, 2016 9:56 AM
To: Bill Hider
Cc: topband
Subject: Re: Topband: 4SQ vs. 8 circle rcv

According to what I read there, there is little difference between the two.
That seems odd. Was some information left out, or did I read the wrong .pptx
file?

73, Mike
www.w0btu.com


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Topband: Carrier on 1814.0 kHz

[John Kaufmann]

For weeks I have been hearing a fairly strong persistent signal on 1814.0
kHz.  It is either a continuous carrier or a series of slow CW dashes.  The
signals I hear periodically from buoy beacons come and go.  This one is
persistent.   I hear it only in darkness and not in daylight, so I presume
it is beyond groundwave range.  From my location near Boston, the signal
peaks at a heading of approximately 230-240 degrees.

 

Anyone else hear this?  If so, from what direction?

 

73, John W1FV

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Re: Topband: New Noise

[John Kaufmann]

A relatively new source of RF noise is solar panel installations.  These are
becoming more widespread and I'm now hearing multiple reports of solar panel
noise from other hams in my area.  The culprit seems to be the power
inverters that use high speed switching circuits and radiate through the
wiring.  I'm dealing with such a problem right now from a new installation
at a neighbor's house.  Fortunately the neighbor is very cooperative and we
are working with the installer (Solar City) to try to fix the problem.

My QTH used to be very quiet but no more.  Good luck.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Bob
Garrett
Sent: Sunday, January 03, 2016 8:07 AM
To: topband@contesting.com
Subject: Topband: New Noise

Greetings,

 

Approximately ten days ago, I experienced increased noise primarily on 160
meters.  After troubleshooting my HI-Z 4 square, I found that the noise was
coming from the NW and is being introduced in to the 4 el array making it
useless to hear weak signals.  I also have a 100 meter DXE bi-directional
beverage.  The noise level on that antenna is up too but still functioning.
My RBOG antennas remain quiet.  One more interesting observation before I
pose a few questions to the collective wisdom of this group.  On 80 meters,
the 4 square and beverage are still working FB.  Since I haven't spent as
much time on 80, I'm not sure if there has been an increase in the noise
floor on that band however, they certainly don't have the increased noise
I'm seeing on Topband.  

 

Yes, I have checked every component of the 4 square array and everything
checks out FB.  

 

So, my thought is someone in the neighborhood got a new electronic gismo for
Christmas.  When I listen on the 400 KHZ band, I hear some huge signals
anytime day or night.  Comparing sounds from the ARRL site, I'm thinking a
light dimmer, phone charger or a dirty wall wort.  

 

My friend Scott, K2CUB will be here in approximately a week and he has some
good noise sniffing equipment.  Now, for the questions:

 

1.If I find a noisy wall wort, will clip on torrids help suppress
the hash or does it need to be changed out with a new one? 

2.   Regarding light dimmers, what is the resolution for those devices.


3.   How about plasma TV?

Any other input appreciated.  I never knew just how quiet my QTH was until
now HI.  73 and HNY Bob K3UL

4.   something new  

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Re: Topband: 160M EWE Problems

[John Kaufmann]

> A reversible array is far and away the best way to convince yourself
> that you have a working receive antenna system. If you reverse it and
> nothing ever changes, well, you're listening to some other antenna! 
> Some (e.g. YCCC array) are supposed to be far more sensitive to near-field

> metal objects than others (e.g. K9AY loop) but even then I'm sure you'll
be
> able to find a convincing F/B on known BCB stations once you have stuff
working right.

The YCCC array and other high-performance receiving arrays have much higher
directivity, and correspondingly higher RDF's, than a K9AY loop.  On 160m,
the YCCC array has an RDF of 12.1 dB while the K9AY loop is 7.7 dB.  This is
not a criticism of the K9AY loop because it is a very simple yet effective
solution for many people.  However, it is a fact of life that achieving
higher directivity in multi-element arrays necessarily means more careful
control of the amplitudes and phases of multiple elements.  A corollary of
that is small perturbations introduced by external influences, like metal
objects, can degrade directivity rather easily.  There is no free lunch.

73, John W1FV

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Re: Topband: 9 circle array

[John Kaufmann]

In general, any metal in the near field of the array will have an effect on
pattern.  This includes radials under the array.  It's hard to predict what
the results will be in a particular situation, but it can be modeled in
EZNEC or other modeling programs.  I've done this in the past and the
results for particular situations range from negligible effects to
significant pattern distortion.   This is also true for any other receiving
array system.  Such antennas are sensitive to metallic objects nearby, and
this needs to be taken into account in laying out an array.

My RX array is installed over the outer part of the radial field for my 160m
transmit vertical system.  Modeling predicted little effect and in practice
I can't say I see any degradation in RX array performance. I also have a
switching arrangement that detunes the transmit vertical while I'm receiving
on the RX array.  This arrangement is described in the user's manual.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Ron Feutz
Sent: Monday, December 07, 2015 10:58 PM
To: topband@contesting.com
Subject: Re: Topband: 9 circle array

The site I have available for one of these systems is part of the former
radial field for my now-defunct 160M 4-square.  The RX array would go where
the ground has radials from the former elements.  These radial wires are
buried under years of accumulated tree stuff and it would not be practical
to remove them.  The radials are not physically connected to the radial
fields of the one or two transmit elements I will be using.

How would the old radial wires affect performance, if at all?

Ron KK9K




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Re: Topband: 9 circle array

[John Kaufmann]

In my earlier post, I neglected to mention the NCJ article was published in
2011.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John
Kaufmann
Sent: Monday, December 07, 2015 8:34 PM
To: 'Glenn Biggerstaff'; topband@contesting.com
Cc: Bruce Herrick
Subject: Re: Topband: 9 circle array

Hello TopBanders,

I am the author of the original NCJ article, published in September/October
and November/December issues, which is the basis for the YCCC/DX Engineering
RX array.  

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Re: Topband: 9 circle array

[John Kaufmann]

Hello TopBanders,

I am the author of the original NCJ article, published in September/October
and November/December issues, which is the basis for the YCCC/DX Engineering
RX array.  I also collaborated extensively with DXE to develop the kits that
are now available exclusively through DXE.  I should also give credit to
Tim, K3LR, on the DXE side for pushing through the collaboration with YCCC
that led to these kits now being available.  Please see:
http://www.dxengineering.com/search/brand/dx-engineering/product-line/yccc-r
eceive-vertical-array-kits-and-kit-packages.  On the YCCC side, WW1M also
gets credit for the original design work on PCB's and custom enclosures.

You can download a copy of the user's manual from:
http://static.dxengineering.com/global/images/instructions/dxe-yccc-3inline.
pdf.  There is extensive technical information on the arrays as well as
detailed kit building instructions in the manual.  To learn more about
what's available, please read the manual.  Please note that I have no
personal affiliation with DXE other than the collaboration I just described.
I make no money for my efforts.

Please direct your technical questions to mailto:yccctechsupp...@verizon.net
and not to DX Engineering.  The e-mail comes directly to me but I prefer you
send e-mail to this address rather than to my personal e-mail address.  My
personal e-mail inbox fills up regularly with lots of unrelated messages and
it is easy for me to miss your e-mails.  The tech support e-mail goes to a
separate inbox where it gets my immediate attention.

I would also be interested in hearing from others who have built and
installed one of these systems.

73, John W1FV



-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Glenn
Biggerstaff
Sent: Monday, December 07, 2015 11:52 AM
To: topband@contesting.com
Subject: Topband: 9 circle array

Has anyone built the DX Engineering version of the YCCC 9 circle array ?I am
considering one and would like anyone's feedback. I have read the NCJ
article and was on the list for the original kit version until it got
squashed. Also is anyone using the W7IUV preamp with an array of verticals?
If so did you build it on a pc board or on perfboard?

Glenn, w...@ww4b.net


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Re: Topband: K1FK to JA Via 160-Meter Long Path

[John Kaufmann]

I just wanted to add another data point to this subject.   I have heard LP
JA's on 160 on several occasions from my location in FN42 (eastern MA),
anywhere from 2120Z to 2200Z in December and January, going back to 1994 or
thereabouts.  I was never able to work any because they were working Europe
and it was not possible for me to break through the Europeans.  

I would estimate that I have heard about 10 different JA stations on LP.
With one exception, they were all from the SE direction, received on a  150m
long Beverage aimed at 140 degrees.  The one exception was one time when I
heard JA1JRK and another JA (I forget the call) peaking from the NE
direction after my sunset.  However, I have not heard any LP JA on 160 in
over 10 years. 

W1 to JA via LP is indeed a very difficult path on 160.  It occurs only very
rarely here and the openings are very short.  Also, as noted, we have to
compete with Europe, which has an opening to JA at the same time.

73, John W1FV

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Re: Topband: Point Shirley

[John Kaufmann]

W1BB's water tower shack was in a little hut at the base of the tower.  I
visited Stew back in the 1970's and got a tour of that QTH.  As I recall,
the shack also served as a civil defense facility, which is the connection
that allowed Stew to operate from there.  I remember Stew telling me that
the local hoodlums would sometimes cut his feedlines, which were out in the
open, and he had to keep a watch on things to stay on the air.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Michael
St. Angelo
Sent: Saturday, February 28, 2015 1:01 PM
To: 'K2RS'; topband@contesting.com
Subject: Re: Topband: Point Shirley

Thanks for he info.

I remember that picture. Where was his shack located for operation from the
watertower?

Mike N2MS


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Re: Topband: Foreign stns using NA remotes for K1N

[John Kaufmann]

W8JI:  The last good DXCC's were when we had a mileage limit. Even then, 
 someone could use a second site. It was actually common to use second
 sites. W1BU did it from a swamp, even W1BB had two stations.

Just for the record, it is true that W1BB had two stations, but they were in
the same town (Winthrop, MA) and literally minutes apart.  One station was
at his home, which was on a tiny, postage stamp lot.   He did most, if not
all, of his serious 160m DXing from the famous water tower location
overlooking the ocean.  I had the good fortune to visit Stew and see both
places back in the 1970's when he was active.  The times I heard him
operating on 160 from the water tower QTH, he would sign W1BB/1 to indicate
he was not at the home station.  

73, John W1FV

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Re: Topband: Non-resonant receive antennas

[John Kaufmann]

My low dipole is broadside NE-SW but at only 10 feet high, it is essentially
omnidirectional in azimuth and a cloud-warmer in elevation.  The instances
where I've seen the dipole provide a receiving advantage have all been short
path, either into JA or VK/ZL after my sunrise.  The sunrise skew path to
the southwest, which occurs only rarely, is always best on the vertical
array.  I did work DU7ET on that path during March and April of last spring.
That path seems to be best in high sunspot years.  The sunset skew path to
Asia has been non-existent here for the last few years and is best in low
sunspot years.  Back in 2006-2007, 9M2AX would come through on this path,
but I have not heard Ross for two or three years now.

I also miss the Singapore BBC station that was on 3915 kHz for many, many
years.  There is still the JA BC station on 3925 and North Korea on 2850.

73, John W1FV

-Original Message-
From: JC [mailto:n...@comcast.net] 
Sent: Friday, December 19, 2014 5:15 PM
To: 'John Kaufmann'; 'Top Band Contesting'
Subject: RE: Topband: Non-resonant receive antennas

Hi John

What is the orientation of you low dipole? I assume similar to XZ0A it is
broadside N-S. In 2010 the SSW SSE propagation  that I am calling TELP
started with  solid copy for 2 weeks in October of XU7ACY around 11:15z and
at 2 weeks per month until March. 2011 was even better and Dec 29 and 30th
were the best days I ever experienced LP. January 2012 this propagation just
stopped from the best day to zero. Nada!!! During  2013 and 2014 LP on 160m
was very rare. 2014 we had some good days with HS0 and DU7 per month., not
even close to what happened 2010 , 2011. Also very few days opening near SS.


I think your observation  is the same as my , the dipole advantage became
non-existent 2013 - 2014 because there was no propagation SSE SSW or TELP. I
used to monitor a BC on 3915 from 9V1 to check for SSE SSW propagation but
the station went QRT last March and I don't have another signal to check
propagation from South Asia anymore so we depend on activity to know is the
band is open and activity has been very low.

I hope the SSW SSE propagation mode will be back next season, or maybe it
will start like it stopped with a huge opening. 

Regards
JCarlos
N4IS


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Re: Topband: Non-resonant receive antennas

[John Kaufmann]

A few years ago, I put up a low, non-resonant dipole, about 150 feet long
and 10 feet high for use as an auxiliary receiving antenna on 160.  My main
receiving antenna was and still is an array of short verticals.  What I
found at my W1 location after I installed the dipole is similar to what N5IA
described at XZ0A.  

If the band was open before my local sunrise (not always the case!), the
verticals would always outperform the dipole by a large amount.  However, as
soon as we hit sunrise, the dipole would suddenly start equaling and then
outperforming the verticals.  The transition would take place in a matter of
a few short minutes.  Past sunrise, DX signals would drop into the noise on
the verticals but would continue to hang in on the dipole.  The dipole would
sometimes extend the opening for me by 5 to 15 minutes, allowing me to make
some contacts (mainly JA and VK, if the band was open in those directions)
that would not have been possible with the vertical array.  Sometimes the DX
would be virtually inaudible on the verticals but Q5, although not strong,
on the dipole.

What is rather interesting, however, is that in the winter seasons of
2012-2013 and 2013-2014, this dipole advantage became non-existent.  The
dipole was never even close to the verticals, either before or after
sunrise.  It caused me to go outside a number of times to see if the dipole
had fallen down, but that was never the case.  Evidently the propagation
mechanisms at work around sunrise have changed from a few years ago, at
least at my QTH.  So far in the 2014-2015 season, the dipole has still not
provided any receiving advantage around sunrise.

I generally don't operate much around local sunset, but I have never seen
any dipole advantage at sunset.  

73, John W1FV

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Re: Topband: 8 circle: DXE vs Hi-Z

[John Kaufmann]

Good points about polarization.  If the signals and/or noise are polarized
predominantly in one state, then RDF may not be a good predictor of SNR
performance, particularly if the antenna receives predominantly in an
orthogonal polarization.  On the other hand, if the polarization state of
the signals and noise evolve randomly with no preference for any one state,
which is often assumed for skywave signals, then RDF will be--on average--a
good receiving metric, subject to the previous stated qualifications about
the spatial distribution of the received noise.  However, some of the past
discussions on this reflector about preferential polarization of skywave
signals on 160 may call into question the assumption of randomly polarized
signals.

73, John W1FV


-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Richard
(Rick) Karlquist
Sent: Wednesday, December 17, 2014 3:19 PM
To: Lee K7TJR; 'Terry Posey'; 'John Kaufmann'; topband@contesting.com
Subject: Re: Topband: 8 circle: DXE vs Hi-Z

All this discussion about RDF overlooks the issue of polarization.  If you
make an array of verticals with a certain RDF (assuming noise comes from all
directions uniformly), the array will be better than an individual vertical
by the RDF factor.  However, what I have found is that a horizontally
polarized antenna, such as a low dipole frequently receives considerably
better than a vertical.  In that case, you would be better off using an
array of low dipoles.  The reason why horizontal polarization can be better
is that the horizontal component of terrestrial based noise is highly
attenuated over distance as a ground wave.

Rick N6RK
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Re: Topband: 8 circle: DXE vs Hi-Z

[John Kaufmann]

A few comments based on my own experience with various receiving arrays:

Circle diameter of the Hi-Z array:  

A circle diameter of 200 feet is specified for the Hi-Z 8-circle array on
160m.  In fact, I have found that there is nothing magic about 200 feet.
It happens to be a good compromise between maximizing RDF and minimizing
sidelobe levels.   You can use smaller circle diameters and still get very
good performance.  

For example, with a circle diameter of 140 feet and the exact same phasing
you would use for 200 feet, you still get a very clean, highly directional
pattern with all lobes to sides and back down by more than 20 dB relative to
the peak of the forward lobe.  The RDF is 12.6 dB at a 20 degree elevation
angle for the 140 foot circle vs. 13.45 dB for the 200 foot circle, so you
do give up a small amount of RDF.  Considering the 140 foot circle uses half
the real estate area of the 200 foot circle, that is a fair compromise for
many people (like me).   

To prove that smaller circle works in practice, I installed exactly that
system and have observed directivity that is totally consistent with the
results I modeled in EZNEC.  Rejection off the sides and back are excellent.
One caveat is that the smaller array is probably less tolerant of amplitude
and phase errors, although I have not done any analysis to quantify that.  I
just built everything very carefully and made the installation as clean as
possible.  I also took care to switch in detuning of my transmit antenna
when receiving on the array.

RDF as a receiving metric:

RDF is indeed a very useful metric for comparing receiving antennas.
However, we need to be aware that it assumes the ambient background
(atmospheric) noise is uniformly distributed in 3-dimensional space, which
is not always true in specific instances.  For this reason, RDF may not
exactly predict the differences between two arrays in any given situation.
It is possible for a system with a lower RDF to equal or even outperform
another system with higher RDF under certain noise conditions.  If the noise
were always uniformly distributed, then RDF would perfectly predict relative
receiving performance (actually SNR). 

The next point about RDF is that it is calculated for a specific signal
arrival direction in three dimensional space.  In terms of azimuth, it is
the peak direction of the forward lobe.  In elevation, it is common practice
to use 20 degrees, which can be considered appropriate for DX reception.  If
the signal arrives from a different azimuth or elevation angle, the SNR
advantage predicted by RDF may not actually be realized.  I have seen a
simple low dipole with a lousy RDF occasionally outperform my 8-circle
system by a large amount when the elevation angle of arriving signals is
very high and the RDF advantage of the array cannot be realized.  

As RDF gets higher, the beamwidth of the antenna system generally gets
narrower.  You can see this if you look at chart #2 in K7TJR's Dayton
presentation (http://www.kkn.net/dayton2014/HiZ_DAYTON_2014_7n2.pdf).  This
brings up another point.  By making the RDF very high, you are necessarily
restricting the angular sector over which the antenna delivers its best
performance.  This is fine as long as the angular sector coincides with a
direction that is important to you.  The flip side is you give up some of
that performance outside that sector.   For switched arrays with a finite
number of selectable directions, that could be a disadvantage when a
direction of interest falls halfway between contiguous switching directions.
Looking at the pattern of the array will tell you what you give up in the
in between directions.

These comments with respect to RDF are not intended to be disparaging.   On
the contrary I do believe RDF is an excellent tool for comparing receiving
antennas.  You just have to aware of what it actually means in practice.

73, John W1FV
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Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz

[John Kaufmann]

It is still coming in after my SR (1200Z) but dropping in strength.  Given
the hour, it is definitely not coming from EU.  The origins are in NA.

73, John W1FV

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Re: Topband: That 1.9 MHz radar signal...

[John Kaufmann]

  Stay tuned, and any additional reports are welcome...I think we have
narrowed it down to something in the Maine/New Brunswick.Nova Scotia areas.

 73,
 Doug K1DG

I would also put Newfoundland in the region of interest.  From my location
in the greater Boston area, the direction of arrival is more east than
northeast (around 75 deg as I said earlier).  I get the same heading every
time I measure the signal and I'm confident in my ability to resolve
directions with my RX array.  The F/B I see on this signal with my array
suggests the signal is not particularly high angle.  The area around St.
John's, Newfoundland area would be right in line with my estimated direction
of arrival.

73, John W1FV

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Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: That 1.9 MHz radar signal...

[John Kaufmann]

I'm not hearing it either at 0054Z.   This transmitter appears to go on and
off, so we can't deduce much unless we know it's on.

Joe (VO1NA), do you have a directional RX antenna?  If so, your readings
could really help narrow down the location.

73, John W1FV


-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
jcr...@mun.ca
Sent: Tuesday, December 09, 2014 7:47 PM
To: topband
Subject: Re: Topband: That 1.9 MHz radar signal...

Just had a quick listen (0044 utc) 1.8-2.0 MHz. CW on the bottom, a bit of
SSB and AM on the upper part of the band.
Other than a bit of crud at 1880 kHz, 160 sounds normal.
Nothing but QRN on 1915.

73
Joe  VO1NA



_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz

[John Kaufmann]

Same estimated heading (~75 deg) from the Boston area and same as last
night.  The relatively big signal strength suggests something in NA rather
than EU.  But that would place it almost out a sea from here, or possibly
very southern VE1 or FP8.  Is there anyone from that area that can give a
report or heading?  If it's Europe, it would point to the CT/EA area, or it
could be northern Africa (CN, EA9, etc.).   The heading is definitely too
far south for the signal to have its origins in places like TF or OX.

73, John W1FV


-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Don Kirk
Sent: Monday, December 08, 2014 8:50 PM
To: Michael Walker
Cc: K2RS; Mike Waters; topband
Subject: Re: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz

Copying the signal again this evening from Indianapolis area at 8:45pm EST
(0145 utc)
Heading is again approximately 75 deg.

Don wd8dsb


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Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz

[John Kaufmann]

It peaks at a heading of about 75 degrees from eastern MA, as best as I can
determine on a Hi-Z 8 circle array.  I made a video of its spectrum as
captured on my Elecraft P3 and posted it on YouTube:
https://www.youtube.com/watch?v=nwe0zp2XiuY.

73, John W1FV
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Using 80m 1/4 vertical on 160

[John Kaufmann]

Hi Mike,

I have a dual-band 160/80 meter vertical system that is based on 1/4-wave
verticals on 80.  I switch in loading coils to make them work on 160.  The
160 capability was added as an afterthought, a few years after it had been
set up for 80.  Perhaps top loading would be somewhat more efficient on 160,
but it would be difficult electrically and mechanically to switch out top
loading on 80.

The key is many radials, over 100 of them ranging in length from 30 feet to
200 feet, depending on the space available.

I won't claim to be the loudest guy on the band, but it does work.  And the
real key, as everyone knows, is being able to hear (I have a separate RX
array).   Without really chasing countries (I am missing many easy ones) I
have something like 250 countries worked and 38 zones towards WAZ from an
unexceptional suburban location.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of W0MU Mike
Fatchett
Sent: Monday, June 02, 2014 12:50 AM
To: topband@contesting.com
Subject: Topband: Using 80m 1/4 vertical on 160

Is this worth trying?

-- 
Mike W0MU

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Re: Topband: Chasing Shaclelton

[John Kaufmann]

I have studied quite a bit of the history of polar exploration and I don't
think there is any correlation between solar activity and the launching of
polar expeditions.  Multiple expeditions were undertaken to discover the
Northwest Passage, the North Pole, and then the South Pole throughout the
1800's and continuing into the early 1900's.  In the early 1900's the final
prize was the South Pole and it is highly unlikely the major expedition
leaders (Scott, Amundsen, and Shackleton) gave any consideration to solar
activity because it was all about a race to be the first there.

Now back to our regularly scheduled program...

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Bruce
Sent: Wednesday, January 08, 2014 5:43 PM
To: topband@contesting.com
Subject: Topband: Chasing Shaclelton

Why did so many polar expeditions take place in periods of high solar
activity ?
Did they believe that sun spots would result in higher earth polar
temperatures?
They found quite the reverse was true.  


Chasing Shackelton premieres today (tonight in NA) on PBS-TV. Check your
local listings for time and station.
http://www.pbs.org/program/chasing-shackleton/

73
Bruce-K1FZ
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Re: Topband: Light fiber question

[John Kaufmann]

There are niche applications, called antenna remoting, where photonic and
fiberoptic technologies are used to transmit RF signals from an antenna to a
remote receiver.  You can buy commercial systems to do this.   I once
designed such a system for a government application to send RF signals from
microwave antennas to receivers that were up to 10 km away.  These
applications exploit the advantages of optical fiber, namely (1) extremely
low loss compared to conventional RF methods that use coax or other copper
media, and (2) the extremely wide bandwidths (thousands of GHz) that can be
supported in fiber.  That's why the telecom industry now uses fiberoptics
for commercial networks, particularly for WAN applications.

However, optical fiber solutions make sense only when the application pushes
the limitations of conventional RF transmission techniques like coax or
twisted pair.  I honestly can't imagine any lowband amateur need where this
would be the case.  And optical solutions come at a cost.  High performance
optical transmitters and receivers that provide low noise and high dynamic
range do exist but they are not cheap by amateur radio standards.  

It's much easier and far less expensive to make coax (or twisted pair, if
you prefer) work properly.

73, John W1FV


_
Topband Reflector

Re: Topband: New beverage

[John Kaufmann]

Go to http://exax.net/index.html and scroll down the page to center fed
steerable wave antenna.  The diagram shows how you can feed a 2-wire
Beverage in the center, or anywhere along its length.  The two transformers
in the middle have center taps that pass signal currents from one side of
the antenna to the other side.  Therefore the entire length of the Beverage
is active at all times.  I built one of these systems many years ago and it
worked very well.

The reflection transformers at the end function exactly the same as the
reflection transformers in a conventional 2-wire Beverage, and convert
common mode currents to transmission line currents that are sent back to the
center of the antenna.  The secondary windings of the two transformers in
the center pick off the transmission line currents and provide receiver
feeds for two directions.  Functionally it is the same as a conventional
2-wire Beverage of the same overall length, except it gives you the
convenience of feeding it anywhere.

73, John W1FV
All good topband ops know how to put up a beverage at night.
_
Topband Reflector

Re: Topband: Measured RG-6 Loss: Solid Copper vs. Copper Clad center conductor

[John Kaufmann]

At KC1XX we also have a 1500-foot feedline run to one of our lowband
receiving antennas. We use RG-6 with copper clad steel center conductor, but
we install a preamp right at the antenna to compensate for feedline loss and
some passive splitting losses at the station.  A potential downside of a
preamp is degradation in dynamic range in a strong signal environment, so
you have to choose the preamp carefully.  We have had very good results with
some very high dynamic range preamps from Clifton Laboratories
(http://cliftonlaboratories.com/current_products.htm).  Incidentally I have
also measured RG-6 feedline loss numbers that are virtually identical to
what Frank has reported.

73, John W1FV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
donov...@starpower.net
Sent: Thursday, January 24, 2013 12:11 PM
To: topband@contesting.com
Cc: Doug Renwick
Subject: Re: Topband: Measured RG-6 Loss: Solid Copper vs. Copper Clad
center conductor

Hi Doug,

Quad shielded RG-6 with a copper clad steel center conductor is an excellent
choice on 160 and 80 meters as long as the cable lengths aren't very long.
Outdoor rated quad shielded CCS RG-6 is more readily available at low prices
(typically less than 10 cents per foot) than solid copper center conductor
RG-6.

RG-6 with a CCS center conductor is a poor choice for the 1500 foot
transmission lines to my 160 and 80 meter receiving antennas.  I wouldn't
hesitate to use CCS RG-6 if my cable lengths were less than 500 feet.

73
Frank
W3LPL

_
Topband Reflector

Re: Topband: Spurious Signal on 1810.8

[John Kaufmann]

About 30 minutes after local SR, the signal is definitely peaking SW from
FN42gk (eastern MA).

73, John W1FV


___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Re: Topband: Spurious Signal on 1810.8

[John Kaufmann]

From eastern MA (FN42gk) the signal is very strong in the daytime and 
nighttime.  This appears to indicate that the source is within groundwave 
distance of me.  I tried getting a direction fix this evening with my RX 
vertical array that can switch in 8 directions.  However, I see very little 
signal change with direction, which tends to indicate the propagation, at 
least after dark, is very high angle.  There may be a very slight peak to the 
southwest or west, but I can't be sure because the differences are so small.  
I'll try getting a daytime fix, maybe tomorrow morning after sunrise, when the 
propagation should become predominantly groundwave and a direction fix should 
be more reliable.

73, John W1FV


___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Re: Topband: Reducing Noise in the Shack

[John Kaufmann]

This report on RFI mitigation may be of interest to folks here:
http://edocs.nps.edu/npspubs/scholarly/TR/2007/NPS-EC-07-002.pdf.  It was
done at the Naval Post Graduate School and almost appears to have been
written for ham applications.  

73, John W1FV
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Re: Topband: Artificial Propagation...?

[John Kaufmann]

Some of you may be thinking of Project West Ford, conducted in the early
1960's by MIT Lincoln Laboratory (where I work now).   Many millions of tiny
needles were launched into orbit to generate an artificial scattering
medium above the earth for long range microwave communications. You must
remember that this was at a time when there were no communications
satellites or long-haul fiberoptic networks, which we take for granted
today.

Technically the project was a success as it demonstrated microwave links
from the east coast to west coast.  However, it required very large ground
terminals with very high transmitter power.  Eventually interest in the
concept died after the first communications satellites were deployed.  Most
of the needles eventually re-entered the atmosphere and disappeared,
although I understand a few still remain in orbit. 

See: http://en.wikipedia.org/wiki/Project_West_Ford and
http://www.damninteresting.com/earths-artificial-ring-project-west-ford/ for
more information.

73, John W1FV

-Original Message-
From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com]
On Behalf Of Arthur Delibert
Sent: Sunday, March 11, 2012 7:59 AM
To: n...@cox.net; k...@frontier.com; topband@contesting.com
Subject: Re: Topband: Artificial Propagation...?


As I remember the earlier project, it was an effort in the early or mid
1960s to create perpetual worldwide twilight by shooting millions of tiny
copper needles into the upper atmosphere.   I remember reading at the time
that they became magnetized and stuck together for that reason.  In any
event, instead of dispersing, they orbitted for awhile as a large clump.
--Art Delibert, KB3FJO
 
 ... ..9 QSB QSB - hw? BK
___
UR RST IS ... ... ..9 QSB QSB - hw? BK