Re: Topband: Antenna analysers in close proximity to BC station.

[Terry Conboy]

On 2012-11-03 8:25 PM, WO0W wrote:
Perhaps you can take a portable transmitter and manual tuner to the 
site. At the point where you wish to place an L network, attach the 
manual tuner and transmitter and adjust the tuner for a good match.  
Take the tuner away from the source of interference, put a 50 Ohm 
dummy load on the tuner input, and measure the impedance on the tuner 
output with the MFJ-259B.  I believe that should be close to the value 
of the impedance of the antenna that was measured, with little or no 
affect from the strong broadcast signal.


In event the application you are using doesn't report the voltages on 
the L network components, the application, Transmission Lines for 
Windows, found on the CD with the late versions of the Antenna Book 
will present values for the L components and the voltage applied to 
each with a given input power.


73 de WOØW
This is a great idea.  But don't forget that the output Z of the 
terminated tuner will look like the conjugate of the antenna impedance.  
In other words, the sign of the reactance (if any) will be reversed.


73, Terry N6RY
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Re: Topband: Antenna analysers in close proximity to BC station

[john battin]

It seems the thread was gone off the original subject, but  and it may have 
been mentioned before  but with my arrays I used an LP-100 with a low power 
transmitter as a source. The high signal levels completely swamps out BC and 
other signals. It reads complex impedences very accurately.
John K9DX

  
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Re: Topband: Antenna analysers in close proximity to BC station

[James Rodenkirch]

Tom: is there data that nail down the horizontal wire to vertical wire ratio?  
I see in that write up by wa1on mention of 2.25:1 h to v but...is that some 
rule that can't be violated or.../

For instance, assuming a vertical section height of 10' I could run a longer 
horizontal section but don't know if that gains me anything.

Thoughts??  Jim R. K9JWV

> From: tsho...@wmata.com
> To: rodenkirch_...@msn.com
> Subject: RE: Topband: Antenna analysers in close proximity to BC station
> Date: Mon, 5 Nov 2012 14:02:58 +
> 
> Sounds to me, like something very close to a "flag" or "rectangular pennant" 
> antenna which would be fed from an end. E.g. 
> http://www.qsl.net/wa1ion/flag/flag_antenna.htm
> 
> But I also note that I found webpages calling your proposal an "elevated 
> ewe", without a ground rod and feeding in a lower corner. 
> 
> I've always had better results with the antennas on the ground with ground 
> rods (e.g. K9AY). Not sure what I've done wrong whenever I tried the elevated 
> flag/pennants but they did not work well for me.
> 
> Tim N3QE
> 
> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James 
> Rodenkirch
> Sent: Monday, November 05, 2012 8:08 AM
> To: topband@contesting.com
> Subject: Re: Topband: Antenna analysers in close proximity to BC station
> 
> So, I'm looking at setting a EWE antenna up - what happens if I simply make 
> it a full loop?  In other words, instead of driving 4' ground rods in at both 
> ends I run a wire between the bottom of the terminating resistor and the 
> matching balun.I'm going to try the shorter version first - 10 feet up 
> and 21 feet across so the full loop will be 62' of wire in that rectangular 
> shape.
> 
> Thank you, in advance, for any feedback  and 72, Jim Rodenkirch K9JWV
> 
> ___
> Topband reflector - topband@contesting.com
  
___
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Re: Topband: Antenna analysers in close proximity to BC station

[James Rodenkirch]

Thanks, Tom - looks like running that "bottom wire" would be "worth it" 'cuz I 
have one 4' ground rod near where I want to install the EWE so that saves the 
cost of buying another rod...Hi Hi.

Appreciate the quick response!  72, Jim Rodenkirch K9JWV

> From: w...@w8ji.com
> To: rodenkirch_...@msn.com; topband@contesting.com
> Date: Mon, 5 Nov 2012 08:19:12 -0500
> Subject: Re: Topband: Antenna analysers in close proximity to BC station
> 
> > So, I'm looking at setting a EWE antenna up - what happens if I simply 
> > make it a full loop?  In other words, instead of driving 4' ground rods in 
> > at both ends I run a wire between the bottom of the terminating resistor 
> > and the matching balun.I'm going to try the shorter version first - 10 
> > feet up and 21 feet across so the full loop will be 62' of wire in that 
> > rectangular shape.
> >
> 
> All EWE's, Flags, Pennants, K9AY's, and everything else are just small 
> terminated loops. They all act like a pair of short verticals that have the 
> cross-fire feedline phasing integrated into the horizontal conductor 
> distance, with the vertical drops actually being the desired antennas.
> 
> You could run a wire across the bottom, except the antenna load and source 
> are not symmetrically placed. This means you would have to ground the bottom 
> wire to prevent the system from being negatively impacted by the 
> asymmetrically of the load and source position.
> 
> 73 Tom
> 
> 
> 
> ___
> Topband reflector - topband@contesting.com
  
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Re: Topband: Antenna analysers in close proximity to BC station

[Tom W8JI]

So, I'm looking at setting a EWE antenna up - what happens if I simply 
make it a full loop?  In other words, instead of driving 4' ground rods in 
at both ends I run a wire between the bottom of the terminating resistor 
and the matching balun.I'm going to try the shorter version first - 10 
feet up and 21 feet across so the full loop will be 62' of wire in that 
rectangular shape.




All EWE's, Flags, Pennants, K9AY's, and everything else are just small 
terminated loops. They all act like a pair of short verticals that have the 
cross-fire feedline phasing integrated into the horizontal conductor 
distance, with the vertical drops actually being the desired antennas.


You could run a wire across the bottom, except the antenna load and source 
are not symmetrically placed. This means you would have to ground the bottom 
wire to prevent the system from being negatively impacted by the 
asymmetrically of the load and source position.


73 Tom



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Topband: Antenna analysers in close proximity to BC station

[Εμμανουήλ Κερατζάκης]

Hi topBanders! 

I live in an area about 10km away from a BC station that transmits on frequency 
981khz and whose power is 200Kw. Whenever I had tried to take measurements with 
a 160m antenna- with the latest equipment on the market- it was always 
impossible. The equipment was always becoming an FSM. The addition of filters 
given for this kind of projects did nothing. However, I did manage to solve the 
problem once and for all by building a simple circuit with materials found in 
almost every shack's junkbox.
The basic circuit was first introduced by W8CGD "Measurement of R+jx " in QST 
June 1965 and was gradually improved throughout time.
I will refer to relative articles like the ones by G3HCT in Radcom, June 1979, 
G3LDO "ARRL ANTENNA COMPENDIUM Vol 4, Vol 5" and lastly a wonderful project and 
its software by SV1BYO which was based on the method of Five-Meter Method and a 
Computer.
The whole set up consists of a power source (in my case, Elecraft K2- 1Watt), a 
digital Voltmeter and a laptop on the base of my antenna. You insert the 
measurements of the Voltmeter in the appropriate program boxes and you 
immediately get the results on the measurements of R and jx of the antenna 
without any interference by the BC station. 

73
Manolis, SV1AOZ
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Re: Topband: Antenna analysers in close proximity to BC station

[James Rodenkirch]

So, I'm looking at setting a EWE antenna up - what happens if I simply make it 
a full loop?  In other words, instead of driving 4' ground rods in at both ends 
I run a wire between the bottom of the terminating resistor and the matching 
balun.I'm going to try the shorter version first - 10 feet up and 21 feet 
across so the full loop will be 62' of wire in that rectangular shape.

Thank you, in advance, for any feedback  and 72, Jim Rodenkirch K9JWV
  
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Re: Topband: Antenna analysers in close proximity to BC station

[Tom W8JI]

Thinking again about this, we have missed out a stage. After measuring the 
tuner output impedance, we need to make a temporary L network which, when 
terminated with 50 ohms, looks like the antenna. Now put the MFJ on this 
terminated network and measure it's R +/- jX values which will represent 
the antenna.


Networks with loss are not always bilaterial.

Since tuners have unevenly distributed losses, they are not bilaterial.

If I adjust a typical tuner for 1:1 SWR into 50 ohms and reverse it, the new 
input impedance will not be 1:1 SWR. 


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Topband: Antenna analysers in close proximity to BC station

[Tom Boucher]

Thinking again about this, we have missed out a stage. After measuring the 
tuner output impedance, we need to make a temporary L network which, when 
terminated with 50 ohms, looks like the antenna. Now put the MFJ on this 
terminated network and measure it's R +/- jX values which will represent the 
antenna.

73
Tom G3OLB

WO0W wrote: 

___
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Topband: Antenna analysers in close proximity to BC station

[Tom Boucher]

That's an interesting idea Red and worth a try.

73
Tom G3OLB

WO0W wrote: 

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Re: Topband: Antenna analysers in close proximity to BC station.

[WO0W]

Hi, Tom;

Perhaps you can take a portable transmitter and manual tuner to the site.  At 
the point where you wish to place an L network, attach the manual tuner and 
transmitter and adjust the tuner for a good match.  Take the tuner away from 
the source of interference, put a 50 Ohm dummy load on the tuner input, and 
measure the impedance on the tuner output with the MFJ-259B.  I believe that 
should be close to the value of the impedance of the antenna that was measured, 
with little or no affect from the strong broadcast signal.

In event the application you are using doesn't report the voltages on the L 
network components, the application, Transmission Lines for Windows, found on 
the CD with the late versions of the Antenna Book will present values for the L 
components and the voltage applied to each with a given input power.

73 de WOØW

From: "Tom Boucher"
To: "160 reflector"
Subject: Topband: Antenna analysers in close proximity to BC station.


A ham friend asked me to design a matching network for his 160 metre end fed 
quarter wave, so I asked him to provide an impedance reading using his 
MFJ-259B. I would then use the Berkley site 
(http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html
  ) to provide the necessary values for an 'L' network, as I have done many 
times at my own station.

 


The readings he provided were total nonsense and quite erratic, so we concluded 
his MFJ-259B was dead. He assured me that he always does a static discharge 
before connecting the MFJ.

 


So I paid him a visit, taking along my Palstar Antenna analyser thing, which 
has always performed well at home, and what-do-you-know, the readings on that 
were also erratic, total nonsense and it behaved in a way I have never seen 
before.

 


Than someone suggested the problem may be due to a 50Kw BC station on 909 KHz, 
situated less than 5 miles away, causing both antenna analysers to misbehave.

 


We ended up with a good old-fashioned link coupled parallel tuned circuit with 
the antenna tapped a few turns up from the ground end. This works fine but he 
is power limited due to arcing across the tuning capacitor. So we would ideally 
like to revert to the 'L' network plan, but how to use the antenna analyser in 
the presence of a high BC station field. Anyone any ideas?

 


73

Tom G3OLB

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Re: Topband: [Topband] Antenna analysers in close proximity to BC station

[DAVID CUTHBERT]

One way to confirm that it is the BC station is to test the antenna during
the day then at night when the (most) BC stations reduce(s) power. You
might even be able to take a valid measurement when the BC station power is
reduced.


Dave WX7G
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Re: Topband: [Topband] Antenna analysers in close proximity to BC station

[N1BUG]

On 11/03/2012 11:00 AM, Pete Smith N4ZR wrote:

I just lugged my TS-930 out to the tower base.  It took all of 5 minutes
to set the Omega match where it needed to be.


I have a two conductor cable permanently run from the tower base to 
the shack, where it is wired to key the rig. That way, all I have to 
take to the tower with me is a small SWR bridge. I also have a 100 
foot "cord" which I can use to extend the rig keying line to the top 
of the tower if and as needed for adjusting whatever antenna might 
be serving as top loading.


This setup pre-dates buying an MFJ-259B a couple of years ago. I 
don't have any strong RF sources nearby, so the latter works fine.


73,
Paul
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Re: Topband: [Topband] Antenna analysers in close proximity to BC station

[Pete Smith N4ZR]

I just lugged my TS-930 out to the tower base.  It took all of 5 minutes 
to set the Omega match where it needed to be.


I wonder what these BC stations run at night - my local one on 1550 runs 
a KW daytime and 6 watts at night.  Single 6L6?


73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.

On 11/3/2012 10:48 AM, Doug Grant wrote:

I had the same annoying problem when troubleshooting my 160M phased
vertical array. Using the MFJ259, neither vertical seemed to have a
j=0 point anywhere near the 160M band, and the readings jumped around
a bit. I concluded that it was AM BC interference. There is a local
station on 1490 a few miles away across salt water, with both analog
and digital signals, and the transmitter is apparently not adjusted
well for the digital, since the signal is very wide.

I tried the MFJ filter and was not successful (if anyone wants to buy
it, contact me off list).

I was able to borrow a vintage General Radio RF impedance bridge from
a local guy, and it worked great. I used my MFJ259 as the signal
source and IC706 as the detector. I could tune the box to drop the
detected signal from pinning the meter to nearly inaudible and read
the R and X to within an ohm easily. Got both verticals to resonate at
1830 (originally one was at 1800, one at 1920 or so). Turned out that
one was about 30 ohms, and one was about 60, which puzzled me.
Numerous experiments using the GR box to corroborate models led me to
figure out that my tower was coupling significantly to the "60-ohm"
element, and I was able to eliminate that problem.

I later found a GR box for sale and bought it.

I suppose one of the newer fancy VNA boxes would also work after
calibration for any filters inserted, but I like old stuff and don't
mind a little calculator or Excel work. I tried unsuccessfully to
persuade a couple of manufacturers to make an updated (lighter,
smaller) version of the GR box.

73,

Doug K1DG
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Re: Topband: Antenna analysers in close proximity to BC station.

[Russ Tobolic]

I have a 2KW ERP station at 1480KHz 1.5 mi north of me and a 20KW ERP at 1300 
KHz south of me .  With that combination my MFJ-259B is TOTALLY useless on 160. 
 I bought the $100 MFJ-731 filter and the 259B was then "almost" TOTALLY 
useless.  Wrapping a $100 bill around my vertical's base loading would have had 
the same effect. The MFJ filter is now good at attracting dust on the shelf for 
the last 5 years.  Now using the LP-100 which works fine.

Russ, N3CO


 From: ZR 
To: Tom Boucher ; 160 reflector 
; Chris G3SVL  
Sent: Friday, November 2, 2012 8:11 PM
Subject: Re: Topband: Antenna analysers in close proximity to BC  station.
 
MFJ sells a filter for that but I dont know how well it works around serious 
BCB RF; 10KW at the high end of the band in 2 directions in about 7-8 miles 
doesnt bother my unfiltered 259B nor do the FM and UHF TV sites about 2 miles 
away.

Carl
KM1H




- Original Message - From: "Chris G3SVL" 
To: "Tom Boucher" ; "160 reflector" 

Sent: Friday, November 02, 2012 6:42 PM
Subject: Re: Topband: Antenna analysers in close proximity to BC station.


> At 21:21 02/11/2012, Tom Boucher wrote:
>> .. but how to use the antenna analyser in the presence of a high BC 
>> station field. Anyone any ideas?
> 
> Hi Tom,
> 
> I have 2.4KW of MW BC transmitter 300m from the base of my 160m antenna, so I 
> know the problem.  I've found an ICE BC filter to be pretty good - but I've 
> only ever used it to tweak a matching system, not to take absolute readings.
> 
> I've used a loaned N8LP LP100A and that worked fine - but of course that's an 
> entirely different measurement system.
> 
> 73 Chris, G3SVL
> ___
> Topband reflector - topband@contesting.com
> 
> 
> -
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1427 / Virus Database: 2441/5369 - Release Date: 11/02/12
> 

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Re: Topband: [Topband] Antenna analysers in close proximity to BC station

[Doug Grant]

I had the same annoying problem when troubleshooting my 160M phased
vertical array. Using the MFJ259, neither vertical seemed to have a
j=0 point anywhere near the 160M band, and the readings jumped around
a bit. I concluded that it was AM BC interference. There is a local
station on 1490 a few miles away across salt water, with both analog
and digital signals, and the transmitter is apparently not adjusted
well for the digital, since the signal is very wide.

I tried the MFJ filter and was not successful (if anyone wants to buy
it, contact me off list).

I was able to borrow a vintage General Radio RF impedance bridge from
a local guy, and it worked great. I used my MFJ259 as the signal
source and IC706 as the detector. I could tune the box to drop the
detected signal from pinning the meter to nearly inaudible and read
the R and X to within an ohm easily. Got both verticals to resonate at
1830 (originally one was at 1800, one at 1920 or so). Turned out that
one was about 30 ohms, and one was about 60, which puzzled me.
Numerous experiments using the GR box to corroborate models led me to
figure out that my tower was coupling significantly to the "60-ohm"
element, and I was able to eliminate that problem.

I later found a GR box for sale and bought it.

I suppose one of the newer fancy VNA boxes would also work after
calibration for any filters inserted, but I like old stuff and don't
mind a little calculator or Excel work. I tried unsuccessfully to
persuade a couple of manufacturers to make an updated (lighter,
smaller) version of the GR box.

73,

Doug K1DG
___
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Re: Topband: Antenna analysers in close proximity to BC station.

[Tom]

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom
> Sent: Friday, November 02, 2012 5:21 PM
> Subject: Topband: Antenna analysers in close proximity to BC station.
> 
> We ended up with a good old-fashioned link coupled parallel tuned circuit
> with the antenna tapped a few turns up from the ground end. This works
> fine but he is power limited due to arcing across the tuning capacitor. So
> we would ideally like to revert to the 'L' network plan, but how to use
> the antenna analyser in the presence of a high BC station field. Anyone
> any ideas?

Tom,

The problem with a low pass filter is it acts like a transmission line and
matching network combination. Even if an analyzer allows calibrating out,
results can be compromised. Results are useless if you cannot calibrate out.

The MFJ filter is a parallel tuned network in parallel with a series tuned
trap for the AM band. Because it corrects as an open circuit at the desired
frequency, it has almost no effect on the reading on the setup frequency. 

The amount of null depth depends on the characteristics of the antenna
system you have and the spacing of the BC station to the frequency you are
measuring. Typically I'd expect 20 dB. If you change the trap inductor to a
higher Q inductor it might get up to 30 dB. 

What won't work is a low pass, high pass, or band pass, unless it appears as
an open with near-zero transmission line effect. This limits the type of
filters that will work to something like the MFJ. The exception is a filter
designed into the detector, or an analyzer and filter that can calibrate out
and tell you what is happening on the other side of the filter. 

I've been telling MFJ for years they need to get an analyzer that uses
selective detectors. IMO that would be more important than sweeps and all
that other stuff. Most people probably just want to know the R and j
accurately, and don't care about a computer interface.

73 Tom

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Re: Topband: Antenna analysers in close proximity to BC station.

[Richard Fry]

Tim N3QE wrote:
And I think clear channel stations do not cut back power at night... do 
clear channel stations actually still exist?


There are about 116 AM broadcast stations in the U.S. using 50 kW 
transmitter power during the day. Some of them reduce power at night, 
however KFMB (760 kHz) San Diego operates with 5 kW non-directional days, 
and 50 kW directional at night.


Some of these 116 stations are directional day and night, and some of those 
have different patterns for day and night.


The directional patterns used by some of these 116 stations may have an ERP 
of around 500 kW at the center of their major lobe.


The stations using 50 kW non-directional day and night are:

KFI  640 kHz  Los Angeles
WSM  650  Memphis
WFAN  660  NYC
WSCR  670  Chicago
KNBR  680  San Francisco
WLW  700  Cincinnati
WGN  720  Chicago
WSB  750  Atlanta
WJR  760  Detroit
WABC  770  NYC
WBBM  780  Chicago
WGY  810 Schenectady
WBAP  820  Ft. Worth
WCCO  830  Minneapolis
WHAS  840  Louisville
KOA  850  Denver
WCBS  880  NYC
WLS  890  Chicago
KDKA  1020  Pittsburgh
WHO  1040  Des Moines
KNX  1070  Los Angeles
WTAM  1100  Cleveland
KMOX  1120  St. Louis
KSL  1160  Salt Lake City
WHAM  1180  Rochester
WOAI  1200  San Antonio
WPHT  1210  Philadelphia

WBZ 1030 Boston and WWL 870 New Orleans use 50 kW day and night, but with 
directional arrays to favor radiation over land areas.


A groundwave field intensity of 2.5 V/m or more can be present at a radius 
of 1 km from the stations in the above list.  That can rise to more than 7 
V/m in the main lobe of a directional station with 500 kW ERP.


The original concept of a clear channel meaning that only one 50 kW, 24/7, 
non-directional station was authorized on that frequency at night is gone. 
The FCC has allowed nighttime service on all of them by stations located far 
enough away from those on the list above when using fairly low power (some 
less than 1 kW), and usually, directional arrays.


The stations listed above are given protection to their nighttime 
(secondary) service areas for interference to their 0.5 mV/m-50% skywave 
contour from stations on the same channels.


RF 


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Re: Topband: Antenna analysers in close proximity to BC station.

[Shoppa, Tim]

At my QTH, many of the local (just a few miles away) AM BC stations cut back 
power a lot at sunset.

The cleanup is remarkable on my transmit Marconi. Before sunset and without any 
reject filters, I literally have 50V RMS between antenna and ground. It can 
light up a neon light on modulation peaks of the nearest stations (OK I cheated 
and built a tuned circuit for 630 WMAL to make that happen! But it does 
happen.) At night it clears up dramatically and is closer to 10V RMS.

It may be as easy as waiting for sunset to do the antenna analyzer thing. (Not 
sure if this helps the original poster in the UK... don't know if UK/Euro 
stations have the same day/night switcheroo that NA stations coordinate. And I 
think clear channel stations do not cut back power at night... do clear channel 
stations actually still exist?).

Tim N3QE

From: Topband [topband-boun...@contesting.com] on behalf of ZR 
[z...@jeremy.mv.com]
Sent: Friday, November 02, 2012 8:11 PM
To: Tom Boucher; 160 reflector; Chris G3SVL
Subject: Re: Topband: Antenna analysers in close proximity to BC  station.

MFJ sells a filter for that but I dont know how well it works around serious
BCB RF; 10KW at the high end of the band in 2 directions in about 7-8 miles
doesnt bother my unfiltered 259B nor do the FM and UHF TV sites about 2
miles away.

Carl
KM1H




- Original Message -
From: "Chris G3SVL" 
To: "Tom Boucher" ; "160 reflector"

Sent: Friday, November 02, 2012 6:42 PM
Subject: Re: Topband: Antenna analysers in close proximity to BC station.


> At 21:21 02/11/2012, Tom Boucher wrote:
>>.. but how to use the antenna analyser in the presence of a high BC
>>station field. Anyone any ideas?
>
> Hi Tom,
>
> I have 2.4KW of MW BC transmitter 300m from the base of my 160m antenna,
> so I know the problem.  I've found an ICE BC filter to be pretty good -
> but I've only ever used it to tweak a matching system, not to take
> absolute readings.
>
> I've used a loaned N8LP LP100A and that worked fine - but of course that's
> an entirely different measurement system.
>
> 73 Chris, G3SVL
> ___
> Topband reflector - topband@contesting.com
>
>
> -
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1427 / Virus Database: 2441/5369 - Release Date: 11/02/12
>

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Re: Topband: Antenna analysers in close proximity to BC station.

[ZR]

MFJ sells a filter for that but I dont know how well it works around serious 
BCB RF; 10KW at the high end of the band in 2 directions in about 7-8 miles 
doesnt bother my unfiltered 259B nor do the FM and UHF TV sites about 2 
miles away.


Carl
KM1H




- Original Message - 
From: "Chris G3SVL" 
To: "Tom Boucher" ; "160 reflector" 


Sent: Friday, November 02, 2012 6:42 PM
Subject: Re: Topband: Antenna analysers in close proximity to BC station.



At 21:21 02/11/2012, Tom Boucher wrote:
.. but how to use the antenna analyser in the presence of a high BC 
station field. Anyone any ideas?


Hi Tom,

I have 2.4KW of MW BC transmitter 300m from the base of my 160m antenna, 
so I know the problem.  I've found an ICE BC filter to be pretty good - 
but I've only ever used it to tweak a matching system, not to take 
absolute readings.


I've used a loaned N8LP LP100A and that worked fine - but of course that's 
an entirely different measurement system.


73 Chris, G3SVL
___
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-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 10.0.1427 / Virus Database: 2441/5369 - Release Date: 11/02/12



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Re: Topband: Antenna analysers in close proximity to BC station.

[Tree]

It is a common solution to put a 160 meter band pass filter on the SWR
meter and it will work.

I had to do this on both 160 meters and 80 meters at A73A.  The high power
AM station was miles away.

Tree N6TR

On Fri, Nov 2, 2012 at 3:22 PM, HAROLD SMITH JR wrote:

> MFJ makes a filter for their Antenna analysers. I am sure that if it does
> not
> work for you, you can get your monies back.
>
> 73..Price W0RI
>
>
>
> I have the same problem with a 50KW FM station a couple of miles away
> affecting my Palstar ZM-30.  It is useable on the rig side of an antenna
> tuning unit, but most of my antennas are self resonate therefore the FM
> broadcast RF rides right into the bridge making it mostly worthless when
> directly attached to any antenna such as a dipole, vertical, yagi, etc.
>
> Sometimes I can get a useable reading if I turn the antenna 90 to the
> broadcast tower, but that only works with the rotatable antennas.
>
> Experiments with filtering using small value caps, small pi networks, a
> series FM trap, or ferrites have been unsuccessful.  Any filter I put in
> front of the analyzer influences the reading substantially.  BTW... this
> broadcast station also comes in on my frequency counter too, with no
> antenna
> attached.
>
> Please let the group know if any of you have come up with a "transparent at
> ham frequencies" inline filter.
>
> 73
>
> Lloyd - N9LB
>
> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com]On Behalf Of Tom
> Boucher
> Sent: Friday, November 02, 2012 4:21 PM
> To: 160 reflector
> Subject: Topband: Antenna analysers in close proximity to BC station.
>
>
>
>
> A ham friend asked me to design a matching network for his 160 metre end
> fed
> quarter wave, so I asked him to provide an impedance reading using his
> MFJ-259B. I would then use the Berkley site
> (
> http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.
> html<http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html>)
>  to provide the necessary values for an 'L' network, as I have done
> many times at my own station.
>
> The readings he provided were total nonsense and quite erratic, so we
> concluded his MFJ-259B was dead. He assured me that he always does a static
> discharge before connecting the MFJ.
>
> So I paid him a visit, taking along my Palstar Antenna analyser thing,
> which
> has always performed well at home, and what-do-you-know, the readings on
> that were also erratic, total nonsense and it behaved in a way I have never
> seen before.
>
> Than someone suggested the problem may be due to a 50Kw BC station on 909
> KHz, situated less than 5 miles away, causing both antenna analysers to
> misbehave.
>
>
>
> We ended up with a good old-fashioned link coupled parallel tuned circuit
> with the antenna tapped a few turns up from the ground end. This works fine
> but he is power limited due to arcing across the tuning capacitor. So we
> would ideally like to revert to the 'L' network plan, but how to use the
> antenna analyser in the presence of a high BC station field. Anyone any
> ideas?
>
>
>
> 73
>
> Tom G3OLB
> ___
> Topband reflector - topband@contesting.com
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.930 / Virus Database: 2441.1.1/5369 - Release Date: 11/02/12
> 02:34:00
>
> ___
> Topband reflector - topband@contesting.com
> ___
> Topband reflector - topband@contesting.com
>
___
Topband reflector - topband@contesting.com

Re: Topband: Antenna analysers in close proximity to BC station.

[Guy Olinger K2AV]

The AIM 4170 (and probably some others) allows you to calibrate THROUGH
filters and coax, etc, to the far side. That way a high pass filter in
front of the unit is completely transparent, and you can see stuff on the
other side with the filter's impedance, passband ripple, etc taken out.
 All done in software.

That feature has been very useful on 160m for eliminating BC interference.
 Beyond BC band there are a lot of uses for remote calibration besides
making filters transparent.  Just one is calibrating to the end of a
feedline, and then using it as a reference to detect problems in the
feedline.  Terminate at the far end and any variation since it was new
shows up as departures from flat readings from the termination.

It DID cost me some money to purchase, it's not the cheep solution, but
I've never looked back.

Having good test equipment that does the job is really worth it.

73, Guy.

On Fri, Nov 2, 2012 at 6:31 PM, Greg - ZL3IX  wrote:

> Hi Tom,
>
> I used to have the same problem with my N2PK VNA, but then I put a
> switchable high pass filter in before the detector - after the reflection
> bridge that is.  Provided that the VNA calibration is done with the filter
> switch in the same state as you intend to do the measurement, it has no
> effect on the readings at all.
>
> Don't know how easy it is to mess with the insides of the either the MFJ
> or Palstar, but if you can get at the detector the same solution should
> work.
>
> 73, Greg, ZL3IX
>
>
> On 2012-11-03 10:21 a.m., Tom Boucher wrote:
>
>>
>> A ham friend asked me to design a matching network for his 160 metre end
>> fed quarter wave, so I asked him to provide an impedance reading using his
>> MFJ-259B. I would then use the Berkley site (http://bwrc.eecs.berkeley.**
>> edu/Research/RF/projects/**60GHz/matching/ImpMatch.html)
>>  to provide the necessary values for an 'L' network, as I have done many
>> times at my own station.
>>
>>
>> The readings he provided were total nonsense and quite erratic, so we
>> concluded his MFJ-259B was dead. He assured me that he always does a static
>> discharge before connecting the MFJ.
>>
>>
>> So I paid him a visit, taking along my Palstar Antenna analyser thing,
>> which has always performed well at home, and what-do-you-know, the readings
>> on that were also erratic, total nonsense and it behaved in a way I have
>> never seen before.
>>
>>
>> Than someone suggested the problem may be due to a 50Kw BC station on 909
>> KHz, situated less than 5 miles away, causing both antenna analysers to
>> misbehave.
>>
>>
>> We ended up with a good old-fashioned link coupled parallel tuned circuit
>> with the antenna tapped a few turns up from the ground end. This works fine
>> but he is power limited due to arcing across the tuning capacitor. So we
>> would ideally like to revert to the 'L' network plan, but how to use the
>> antenna analyser in the presence of a high BC station field. Anyone any
>> ideas?
>>
>>
>> 73
>>
>> Tom G3OLB
>> __**_
>> Topband reflector - topband@contesting.com
>>
>>
> __**_
> Topband reflector - topband@contesting.com
>
___
Topband reflector - topband@contesting.com

Re: Topband: Antenna analysers in close proximity to BC station.

[Chris G3SVL]

At 21:21 02/11/2012, Tom Boucher wrote:
.. but how to use the antenna analyser in the presence of a high 
BC station field. Anyone any ideas?


Hi Tom,

I have 2.4KW of MW BC transmitter 300m from the base of my 160m 
antenna, so I know the problem.  I've found an ICE BC filter to be 
pretty good - but I've only ever used it to tweak a matching system, 
not to take absolute readings.


I've used a loaned N8LP LP100A and that worked fine - but of course 
that's an entirely different measurement system.


73 Chris, G3SVL
___
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Re: Topband: Antenna analysers in close proximity to BC station.

[Greg - ZL3IX]

Hi Tom,

I used to have the same problem with my N2PK VNA, but then I put a 
switchable high pass filter in before the detector - after the 
reflection bridge that is.  Provided that the VNA calibration is done 
with the filter switch in the same state as you intend to do the 
measurement, it has no effect on the readings at all.


Don't know how easy it is to mess with the insides of the either the MFJ 
or Palstar, but if you can get at the detector the same solution should 
work.


73, Greg, ZL3IX


On 2012-11-03 10:21 a.m., Tom Boucher wrote:


A ham friend asked me to design a matching network for his 160 metre end fed 
quarter wave, so I asked him to provide an impedance reading using his 
MFJ-259B. I would then use the Berkley site 
(http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html
 ) to provide the necessary values for an 'L' network, as I have done many 
times at my own station.

  


The readings he provided were total nonsense and quite erratic, so we concluded 
his MFJ-259B was dead. He assured me that he always does a static discharge 
before connecting the MFJ.

  


So I paid him a visit, taking along my Palstar Antenna analyser thing, which 
has always performed well at home, and what-do-you-know, the readings on that 
were also erratic, total nonsense and it behaved in a way I have never seen 
before.

  


Than someone suggested the problem may be due to a 50Kw BC station on 909 KHz, 
situated less than 5 miles away, causing both antenna analysers to misbehave.

  


We ended up with a good old-fashioned link coupled parallel tuned circuit with 
the antenna tapped a few turns up from the ground end. This works fine but he 
is power limited due to arcing across the tuning capacitor. So we would ideally 
like to revert to the 'L' network plan, but how to use the antenna analyser in 
the presence of a high BC station field. Anyone any ideas?

  


73

Tom G3OLB
___
Topband reflector - topband@contesting.com



___
Topband reflector - topband@contesting.com

Re: Topband: Antenna analysers in close proximity to BC station.

[HAROLD SMITH JR]

MFJ makes a filter for their Antenna analysers. I am sure that if it does not 
work for you, you can get your monies back.

73..Price W0RI



I have the same problem with a 50KW FM station a couple of miles away
affecting my Palstar ZM-30.  It is useable on the rig side of an antenna
tuning unit, but most of my antennas are self resonate therefore the FM
broadcast RF rides right into the bridge making it mostly worthless when
directly attached to any antenna such as a dipole, vertical, yagi, etc.

Sometimes I can get a useable reading if I turn the antenna 90 to the
broadcast tower, but that only works with the rotatable antennas.

Experiments with filtering using small value caps, small pi networks, a
series FM trap, or ferrites have been unsuccessful.  Any filter I put in
front of the analyzer influences the reading substantially.  BTW... this
broadcast station also comes in on my frequency counter too, with no antenna
attached.

Please let the group know if any of you have come up with a "transparent at
ham frequencies" inline filter.

73

Lloyd - N9LB

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com]On Behalf Of Tom
Boucher
Sent: Friday, November 02, 2012 4:21 PM
To: 160 reflector
Subject: Topband: Antenna analysers in close proximity to BC station.




A ham friend asked me to design a matching network for his 160 metre end fed
quarter wave, so I asked him to provide an impedance reading using his
MFJ-259B. I would then use the Berkley site
(http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.
html ) to provide the necessary values for an 'L' network, as I have done
many times at my own station.

The readings he provided were total nonsense and quite erratic, so we
concluded his MFJ-259B was dead. He assured me that he always does a static
discharge before connecting the MFJ.

So I paid him a visit, taking along my Palstar Antenna analyser thing, which
has always performed well at home, and what-do-you-know, the readings on
that were also erratic, total nonsense and it behaved in a way I have never
seen before.

Than someone suggested the problem may be due to a 50Kw BC station on 909
KHz, situated less than 5 miles away, causing both antenna analysers to
misbehave.



We ended up with a good old-fashioned link coupled parallel tuned circuit
with the antenna tapped a few turns up from the ground end. This works fine
but he is power limited due to arcing across the tuning capacitor. So we
would ideally like to revert to the 'L' network plan, but how to use the
antenna analyser in the presence of a high BC station field. Anyone any
ideas?



73

Tom G3OLB
___
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No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.930 / Virus Database: 2441.1.1/5369 - Release Date: 11/02/12
02:34:00

___
Topband reflector - topband@contesting.com
___
Topband reflector - topband@contesting.com

Re: Topband: Antenna analysers in close proximity to BC station.

[Lloyd Berg - N9LB]

I have the same problem with a 50KW FM station a couple of miles away
affecting my Palstar ZM-30.  It is useable on the rig side of an antenna
tuning unit, but most of my antennas are self resonate therefore the FM
broadcast RF rides right into the bridge making it mostly worthless when
directly attached to any antenna such as a dipole, vertical, yagi, etc.

Sometimes I can get a useable reading if I turn the antenna 90 to the
broadcast tower, but that only works with the rotatable antennas.

Experiments with filtering using small value caps, small pi networks, a
series FM trap, or ferrites have been unsuccessful.  Any filter I put in
front of the analyzer influences the reading substantially.  BTW... this
broadcast station also comes in on my frequency counter too, with no antenna
attached.

Please let the group know if any of you have come up with a "transparent at
ham frequencies" inline filter.

73

Lloyd - N9LB

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com]On Behalf Of Tom
Boucher
Sent: Friday, November 02, 2012 4:21 PM
To: 160 reflector
Subject: Topband: Antenna analysers in close proximity to BC station.




A ham friend asked me to design a matching network for his 160 metre end fed
quarter wave, so I asked him to provide an impedance reading using his
MFJ-259B. I would then use the Berkley site
(http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.
html ) to provide the necessary values for an 'L' network, as I have done
many times at my own station.

The readings he provided were total nonsense and quite erratic, so we
concluded his MFJ-259B was dead. He assured me that he always does a static
discharge before connecting the MFJ.

So I paid him a visit, taking along my Palstar Antenna analyser thing, which
has always performed well at home, and what-do-you-know, the readings on
that were also erratic, total nonsense and it behaved in a way I have never
seen before.

Than someone suggested the problem may be due to a 50Kw BC station on 909
KHz, situated less than 5 miles away, causing both antenna analysers to
misbehave.



We ended up with a good old-fashioned link coupled parallel tuned circuit
with the antenna tapped a few turns up from the ground end. This works fine
but he is power limited due to arcing across the tuning capacitor. So we
would ideally like to revert to the 'L' network plan, but how to use the
antenna analyser in the presence of a high BC station field. Anyone any
ideas?



73

Tom G3OLB
___
Topband reflector - topband@contesting.com
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.930 / Virus Database: 2441.1.1/5369 - Release Date: 11/02/12
02:34:00

___
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Re: Topband: Antenna analysers in close proximity to BC station.

[Bob K6UJ]

Tom,

I will be interested  to see what the solution(s) will be  for the BC station 
interference.

Wanted to thank for the reference to the impedance problem calculators.  They 
are great!  

73,
Bob
K6UJ


On Nov 2, 2012, at 2:21 PM, Tom Boucher wrote:

> 
> 
> A ham friend asked me to design a matching network for his 160 metre end fed 
> quarter wave, so I asked him to provide an impedance reading using his 
> MFJ-259B. I would then use the Berkley site 
> (http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html
>  ) to provide the necessary values for an 'L' network, as I have done many 
> times at my own station.
> 
> 
> 
> The readings he provided were total nonsense and quite erratic, so we 
> concluded his MFJ-259B was dead. He assured me that he always does a static 
> discharge before connecting the MFJ.
> 
> 
> 
> So I paid him a visit, taking along my Palstar Antenna analyser thing, which 
> has always performed well at home, and what-do-you-know, the readings on that 
> were also erratic, total nonsense and it behaved in a way I have never seen 
> before. 
> 
> 
> 
> Than someone suggested the problem may be due to a 50Kw BC station on 909 
> KHz, situated less than 5 miles away, causing both antenna analysers to 
> misbehave.
> 
> 
> 
> We ended up with a good old-fashioned link coupled parallel tuned circuit 
> with the antenna tapped a few turns up from the ground end. This works fine 
> but he is power limited due to arcing across the tuning capacitor. So we 
> would ideally like to revert to the 'L' network plan, but how to use the 
> antenna analyser in the presence of a high BC station field. Anyone any ideas?
> 
> 
> 
> 73
> 
> Tom G3OLB
> ___
> Topband reflector - topband@contesting.com

___
Topband reflector - topband@contesting.com

Topband: Antenna analysers in close proximity to BC station.

[Tom Boucher]

A ham friend asked me to design a matching network for his 160 metre end fed 
quarter wave, so I asked him to provide an impedance reading using his 
MFJ-259B. I would then use the Berkley site 
(http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html
 ) to provide the necessary values for an 'L' network, as I have done many 
times at my own station.

 

The readings he provided were total nonsense and quite erratic, so we concluded 
his MFJ-259B was dead. He assured me that he always does a static discharge 
before connecting the MFJ.

 

So I paid him a visit, taking along my Palstar Antenna analyser thing, which 
has always performed well at home, and what-do-you-know, the readings on that 
were also erratic, total nonsense and it behaved in a way I have never seen 
before. 

 

Than someone suggested the problem may be due to a 50Kw BC station on 909 KHz, 
situated less than 5 miles away, causing both antenna analysers to misbehave.

 

We ended up with a good old-fashioned link coupled parallel tuned circuit with 
the antenna tapped a few turns up from the ground end. This works fine but he 
is power limited due to arcing across the tuning capacitor. So we would ideally 
like to revert to the 'L' network plan, but how to use the antenna analyser in 
the presence of a high BC station field. Anyone any ideas?

 

73

Tom G3OLB
___
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