Re: Topband: Thanks

[Larry via Topband]

hi guys,
you have me confused. 4U1ITU is easy from southern arizona. Bordered by 
France/Switzerland and Germany all are easily workable.
I don't understand the "black hole" comments.
Larry


-Original Message-
From: Wes 
To: topband 
Sent: Mon, 25 Feb 2019 1:50
Subject: Re: Topband: Thanks

Even blacker I think, but with the noise and SSB splatter, who can be sure?

Wes  N7WS

On 2/24/2019 1:25 PM, w...@w5zn.org wrote:
> The propagation into Arkansas on 160 meters from 4U1ITU is pretty much a 
> black 
> hole. I can only imagine what is like further west
>
> Joel W5ZN

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Re: Topband: Thanks

[Wes]

Even blacker I think, but with the noise and SSB splatter, who can be sure?

Wes  N7WS

On 2/24/2019 1:25 PM, w...@w5zn.org wrote:
The propagation into Arkansas on 160 meters from 4U1ITU is pretty much a black 
hole. I can only imagine what is like further west


Joel W5ZN


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Re: Topband: Thanks

[Jorge Diez - CX6VM]

I hope so

and that the operatior can stop EU wall

73,
Jorge
CX6VM/CW5W

El dom., 24 feb. 2019 a las 12:56, Raymond Benny ()
escribió:

> Tnx for the info.
>
> Wish someone else could put on 4U1ITU again but perhaps with a little
> notice. It's even rarer on the West coast.
>
> Ray,
> N6VR
>
>
>
> On Sun, Feb 24, 2019, 7:01 AM  wrote:
>
> > Last night Dave, K1ZZ, who is in Geneva at the Conference Preparatory
> > Meeting in advance of this fall's WRC, was able to fire up 4U1ITU on CW.
> > 4U1ITU is still a much needed DXCC entity in North America. Obviously,
> > the CQWW 160 SSB contest was this weekend. There is considerable noise
> > on 160 meters at 4U1ITU as you can imagine. Not to help matters, once
> > the tram fires up in Geneva it adds to the hash noise on the band thus
> > the decision to focus on CW rather than struggle even harder with SSB in
> > the contest.
> >
> > Dave chose to operate low in the band, on 1811 KHz initially listening
> > up 1, in an effort to avoid as much of the contest traffic as possible.
> > Later in the night he shifted to listening down at 1805 KHz to avoid
> > some SSB splatter from EU a little higher up.
> >
> > Dave was able to give about 40 USA stations a new one, mostly from
> > around 0500z to 0630z when we had some decent propagation.
> >
> > During the evening there were around 10 stations that came on 1811, or
> > close enough to disrupt the ability to hear 4U1ITU, who were politely
> > asked to QSY and everyone did. As someone who needed 4U1ITU for a new
> > DXCC on 160, and on behalf of the others, I want to thank you all for
> > understanding and being accommodating. It was greatly appreciated.
> >
> > Thanks again.
> >
> > 73 Joel W5ZN
> >
> > _
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> > Reflector
> >
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>


-- 
73,
Jorge
CX6VM/CW5W
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Re: Topband: Thanks

[Lee STRAHAN]

Rich K7ZV was reporting he was hearing Dave very light from his hilltop place 
in southern OR. He was unable to make the Q. I have a pretty high noise floor 
at the moment and did not hear anything except a ping or 2 at some 200 miles 
North of Rich.
Sigh,
Lee   K7TJR  OR

-Original Message-
From: Topband  On Behalf Of w...@w5zn.org
Sent: Sunday, February 24, 2019 12:26 PM
To: Tree 
Cc: 160 ; Raymond Benny 
Subject: Re: Topband: Thanks

The propagation into Arkansas on 160 meters from 4U1ITU is pretty much a black 
hole. I can only imagine what is like further west

Joel W5ZN


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Re: Topband: Thanks

[w5zn]

The propagation into Arkansas on 160 meters from 4U1ITU is pretty much a 
black hole. I can only imagine what is like further west


Joel W5ZN


On 2019-02-24 11:09, Tree wrote:
Back in 1990, I lived about 30 minutes from 4U1ITU and put about 25K 
QSOs
in their log during my 14 month stay.  I remember operating the ARRL 
160

contest and giving out a few QSOs.  They each were like pulling teeth.

160CW   1-Dec-90 05:281  K5NA/2 599
160CW   1-Dec-90 05:322  W1PH   599
160CW   1-Dec-90 05:443  K1ZM   599
160CW   1-Dec-90 06:014  KZ2S   599
160CW   1-Dec-90 06:195  NK1K   599
160CW   1-Dec-90 06:216  G0AWF  599
160CW   1-Dec-90 06:257  K2WI   599

The QTH is no doubt very noisy - even more than before.  I don't 
remember a
tram back then.  The other issue with the station is the path towards 
the
USA is pretty poor.  There are the Jura mountains right in the way.  
Lake
Geneva is nestled between the Jura and the Alps.  The QTH I had at home 
was
right against the Alps - and I have better success working the West 
Coast

long path on 40 than I did short path.

For us on the West coast - it would take one of those nights where we 
can
work several layers deep into Europe - which is a pretty rare event.  
Then
- that would have to be coupled with someone being focused on the band 
on
the other end.  Probably the best hope would be for some European 
station

who is normally active on 160 to be able to commute to the station when
they are aware conditions are excellent.  This was a possibility when
Pierre, HB9AMO was on the band some 30 years ago (Pierre was the first
signal I ever heard from Europe back in 1986 from Oregon - I heard
"9AMO").

Sadly - that sort of puts it in the same class as working C31 or 3A - 
which
would probably take a DX-pedition to with big antennas to make it out 
West

and focused operating over a two week period during good conditions.

Tree N6TR/7
Manning, OR

On Sun, Feb 24, 2019 at 7:56 AM Raymond Benny  
wrote:



Tnx for the info.

Wish someone else could put on 4U1ITU again but perhaps with a little
notice. It's even rarer on the West coast.

Ray,
N6VR



On Sun, Feb 24, 2019, 7:01 AM  wrote:

> Last night Dave, K1ZZ, who is in Geneva at the Conference Preparatory
> Meeting in advance of this fall's WRC, was able to fire up 4U1ITU on CW.
> 4U1ITU is still a much needed DXCC entity in North America. Obviously,
> the CQWW 160 SSB contest was this weekend. There is considerable noise
> on 160 meters at 4U1ITU as you can imagine. Not to help matters, once
> the tram fires up in Geneva it adds to the hash noise on the band thus
> the decision to focus on CW rather than struggle even harder with SSB in
> the contest.
>
> Dave chose to operate low in the band, on 1811 KHz initially listening
> up 1, in an effort to avoid as much of the contest traffic as possible.
> Later in the night he shifted to listening down at 1805 KHz to avoid
> some SSB splatter from EU a little higher up.
>
> Dave was able to give about 40 USA stations a new one, mostly from
> around 0500z to 0630z when we had some decent propagation.
>
> During the evening there were around 10 stations that came on 1811, or
> close enough to disrupt the ability to hear 4U1ITU, who were politely
> asked to QSY and everyone did. As someone who needed 4U1ITU for a new
> DXCC on 160, and on behalf of the others, I want to thank you all for
> understanding and being accommodating. It was greatly appreciated.
>
> Thanks again.
>
> 73 Joel W5ZN
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
_
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Reflector


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Re: Topband: Thanks

[Tree]

Back in 1990, I lived about 30 minutes from 4U1ITU and put about 25K QSOs
in their log during my 14 month stay.  I remember operating the ARRL 160
contest and giving out a few QSOs.  They each were like pulling teeth.

160CW   1-Dec-90 05:281  K5NA/2 599
160CW   1-Dec-90 05:322  W1PH   599
160CW   1-Dec-90 05:443  K1ZM   599
160CW   1-Dec-90 06:014  KZ2S   599
160CW   1-Dec-90 06:195  NK1K   599
160CW   1-Dec-90 06:216  G0AWF  599
160CW   1-Dec-90 06:257  K2WI   599

The QTH is no doubt very noisy - even more than before.  I don't remember a
tram back then.  The other issue with the station is the path towards the
USA is pretty poor.  There are the Jura mountains right in the way.  Lake
Geneva is nestled between the Jura and the Alps.  The QTH I had at home was
right against the Alps - and I have better success working the West Coast
long path on 40 than I did short path.

For us on the West coast - it would take one of those nights where we can
work several layers deep into Europe - which is a pretty rare event.  Then
- that would have to be coupled with someone being focused on the band on
the other end.  Probably the best hope would be for some European station
who is normally active on 160 to be able to commute to the station when
they are aware conditions are excellent.  This was a possibility when
Pierre, HB9AMO was on the band some 30 years ago (Pierre was the first
signal I ever heard from Europe back in 1986 from Oregon - I heard
"9AMO").

Sadly - that sort of puts it in the same class as working C31 or 3A - which
would probably take a DX-pedition to with big antennas to make it out West
and focused operating over a two week period during good conditions.

Tree N6TR/7
Manning, OR

On Sun, Feb 24, 2019 at 7:56 AM Raymond Benny  wrote:

> Tnx for the info.
>
> Wish someone else could put on 4U1ITU again but perhaps with a little
> notice. It's even rarer on the West coast.
>
> Ray,
> N6VR
>
>
>
> On Sun, Feb 24, 2019, 7:01 AM  wrote:
>
> > Last night Dave, K1ZZ, who is in Geneva at the Conference Preparatory
> > Meeting in advance of this fall's WRC, was able to fire up 4U1ITU on CW.
> > 4U1ITU is still a much needed DXCC entity in North America. Obviously,
> > the CQWW 160 SSB contest was this weekend. There is considerable noise
> > on 160 meters at 4U1ITU as you can imagine. Not to help matters, once
> > the tram fires up in Geneva it adds to the hash noise on the band thus
> > the decision to focus on CW rather than struggle even harder with SSB in
> > the contest.
> >
> > Dave chose to operate low in the band, on 1811 KHz initially listening
> > up 1, in an effort to avoid as much of the contest traffic as possible.
> > Later in the night he shifted to listening down at 1805 KHz to avoid
> > some SSB splatter from EU a little higher up.
> >
> > Dave was able to give about 40 USA stations a new one, mostly from
> > around 0500z to 0630z when we had some decent propagation.
> >
> > During the evening there were around 10 stations that came on 1811, or
> > close enough to disrupt the ability to hear 4U1ITU, who were politely
> > asked to QSY and everyone did. As someone who needed 4U1ITU for a new
> > DXCC on 160, and on behalf of the others, I want to thank you all for
> > understanding and being accommodating. It was greatly appreciated.
> >
> > Thanks again.
> >
> > 73 Joel W5ZN
> >
> > _
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> > Reflector
> >
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
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Re: Topband: Thanks

[Raymond Benny]

Tnx for the info.

Wish someone else could put on 4U1ITU again but perhaps with a little
notice. It's even rarer on the West coast.

Ray,
N6VR



On Sun, Feb 24, 2019, 7:01 AM  wrote:

> Last night Dave, K1ZZ, who is in Geneva at the Conference Preparatory
> Meeting in advance of this fall's WRC, was able to fire up 4U1ITU on CW.
> 4U1ITU is still a much needed DXCC entity in North America. Obviously,
> the CQWW 160 SSB contest was this weekend. There is considerable noise
> on 160 meters at 4U1ITU as you can imagine. Not to help matters, once
> the tram fires up in Geneva it adds to the hash noise on the band thus
> the decision to focus on CW rather than struggle even harder with SSB in
> the contest.
>
> Dave chose to operate low in the band, on 1811 KHz initially listening
> up 1, in an effort to avoid as much of the contest traffic as possible.
> Later in the night he shifted to listening down at 1805 KHz to avoid
> some SSB splatter from EU a little higher up.
>
> Dave was able to give about 40 USA stations a new one, mostly from
> around 0500z to 0630z when we had some decent propagation.
>
> During the evening there were around 10 stations that came on 1811, or
> close enough to disrupt the ability to hear 4U1ITU, who were politely
> asked to QSY and everyone did. As someone who needed 4U1ITU for a new
> DXCC on 160, and on behalf of the others, I want to thank you all for
> understanding and being accommodating. It was greatly appreciated.
>
> Thanks again.
>
> 73 Joel W5ZN
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
_
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Re: Topband: Thanks to K3LR and DX Engineering! (Was: RE: DX Engineering 4-Square RX Antenna: Element Amplifiers?)

[john]

yes,, says a lot,, a whole lot for dx engineering73 john

On 9/24/2015 4:58 PM, Jeff Maass K8ND wrote:

Thanks to all who replied with suggestions and information!

Tim Duffy K3LR responded on behalf of DX Engineering, and offered to have
our 4-square amplifiers checked-out and calibrated to match within +/- 0.1
dB. They are also going to look at the DXE-RFS controller to assure that it
is functioning correctly to switch the delay lines and antenna feeds when
commanded. All this at no cost to us, including shipping!

Thanks to Tim and to DX Engineering for this fantastic response!

We've been using the DXE 4-Square RX antenna system at PJ2T since 2006. When
operating on 160 and 80-meters from just 12 degrees North of the Equator,
receiving antennas that work are very important.   The DX Engineering
antenna has been an important resource in some very successful PJ2T CQWW CW
and CQWW 160 CW Contest operations, including four consecutive 1st Worldwide
finishes in the CQWW 160 CW Contest.

Thanks again, Tim K3LR!

73,  Jeff  K8ND

  


From: Jeff Maass K8ND [mailto:jma...@k8nd.com]
Sent: Tuesday, September 22, 2015 9:17 PM
To: 'cq-cont...@contesting.com'  >
Cc: 'Jim Galm (j...@w8wts.com  )'  >
Subject: DX Engineering 4-Square RX Antenna: Element Amplifiers?

  


In January, Jim W8WTS and I were at PJ2T for CQWW 160 CW, and we both noted
that our DX Engineering 4-square RX antenna did not appear to perform as
well as usual. It is a 98-foot configuration using 102-inch whips.

It is set up "field day style" for contests when we use it (i.e. not set up
permanently), and so we thought that perhaps all the handling over the years
might have caused problems with the feed and delay cables. We had a Array
Solutions AIM-4170C VNA with us, and confirmed that all the cables were
still  in good shape and were of the correct lengths.

We decided to bring home the four DXE ARAV3 active antenna amplifiers to
diagnose at home (we left the four whips on Curacao!). W8WTS has an Array
Solutions VNA-2180 2-port device, and captured curves for inputs and
outputs. His analysis is shown below. Screen captures of the resulting
curves are in an archive at:
http://www.k8nd.com/Radio/PJ2T_DXE_4-Square_amps_ photos.zip
 .

  


"Each amp has a port a sweep and a port b sweep.  There is also a reference
pair of sweeps with the amplifier jumpered out of the circuit, to verify
that the ports are calibrated correctly.  The port a sweep shows the
impedance looking into the antenna port.  We want the input impedance to be
extremely high; higher is better.  There is a peak in the Z because of the
parallel LC filter on the input of the AVA-2 that rejects out of band
signals.  You can see that they are all set correctly to peak on 1.8 Mhz.

  


"The port b sweep shows the magnitude and angle of S21.  S21 is the forward
voltage gain of the amplifier.  We want the forward voltage gain to be
exactly 1, which is shown on the graphs as 0 dB.  The four amplifiers have
different gains at 1.8 MHz, but they are very close.  The lowest is amp 1 at
1.2 dB and the highest is amp 4 at 1.4 dB.  A gain difference of 0.2 dB is
very small, but it might make a difference. "

  


They appear to be working OK, but what we don't know is:

   QUERY: How much of a gain discrepancy is tolerable in the element
amplifiers in a DXE four square?

73,  Jeff  K8ND

  

  

  

  

  

  

  


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Re: Topband: Thanks!

[ZR]

Are you now claiming that the thousands of bead choke baluns in use for 
decades at HF and 6M dont work?


I suspect that those who have been happy with the results in mimizing 
feedline radiation would heartily disagree


Carl
KM1H


- Original Message - 
From: Jim Brown j...@audiosystemsgroup.com

To: topband@contesting.com
Sent: Tuesday, May 21, 2013 11:58 AM
Subject: Re: Topband: Thanks!



On 5/18/2013 10:35 AM, Charlie Cunningham wrote:
  If you get the larger beads/tubes thatwill fit over RG-213 etc. you can 
make excellent 1:1 current baluns by slipping them over the cable before 
putting the connector on.


These are not excellent 1:1 current baluns below about 75 MHz. Below 
that range, they are a lousy common mode choke, because they are 
inductive. Inductive chokes resonate with a line that is capacitive, so 
they actually increase the current. A line shorter than a quarter wave is 
capacitive; so is a line between a half wave and 3/4 wave. And so on. 
That's why we want a choke that is highly resistive -- the resistive 
component always reduces common mode current, which is the objective of a 
common mode choke (the so-called current balun.)


There's an extensive discussion of this in my RFI tutorial, and also in 
the Coax Chokes power point (which is a pdf).  On my website. 
k9yc.com/publish.htm


73, Jim K9YC



All good topband ops know how to put up a beverage at night.
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All good topband ops know how to put up a beverage at night.
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Topband Reflector

Re: Topband: Thanks!

[ZR]

On 5/21/2013 1:18 PM, ZR wrote:
Are you now claiming that the thousands of bead choke baluns in use for 
decades at HF and 6M dont work?


I have published extensively on this, first in 2005 in a peer reviewed AES 
paper, and later in my RFI tutorial. All of this work is on my website. 
W1HIS published his work on this in 2006. A few years ago, an engineering 
supervisor at CIA sent me work from an US Army research group prepared in 
the 70s reaching the same conclusions as I had.  And literature searches 
for my AES paper found references (in a European ferrite manufacturer's 
applications notes) to the importance of resistance in chokes as far back 
as the 50s.



You didnt answer the question and anybody can write papers and create a 
website with a lot of readily available data plus new items that isnt open 
to peer review.


Ive also mentioned to you and others several times over the years of my 
actual involvement with the CIA/DOD Tempest program. There were contributors 
nationwide, companies and individuals, that all created the results that you 
appear to have discovered later.





I suspect that those who have been happy with the results in mimizing 
feedline radiation would heartily disagree


Many people believe many things that are not true.


That is a typical response to criticism or simply asking a question. It 
serves no useful purpose altho it is rather common on Topband.



Many false beliefs
are based on a grain of truth. The generalized assumption in ham 
literature has been that 500 ohms choking Z is sufficient to prevent 
pattern distortion caused by feedline radiation, but W1HIS showed that 
increasing choking Z to the range of 5,000 ohms can significantly reduce 
receive noise.


More nonsense as well over 1000 Ohms, was recognized by the late 70's among 
the serious contesters. While this is Topband, ferrite use isnt limited to 
it and you show broadband graphs.
My own Mosely TA-33 kits did wonders to stop feedline radiation and were 
soon popular with Hy Gain, KLM and others.



When I saw his paper, I immediately tried multi-turn
chokes on an antenna that was picking up a lot of noise. The choke reduced 
the noise by nearly 10 dB. Since I published my work, hundreds of hams 
have told me they have had similar results.


I thought it was you or maybe Tom that belittled that paper



73, Jim K9YC


In any case 43 mix large beads and 2.4 toroids did well until 31 came along 
and it still has its benefits.


Has anyone asked Fair-Rite about producing the 2.4 and large beads in 73 
mix?


The following older paper with update should be read by all considering the 
authors 35 year involvement with Fair-Rite. Dont be surprised if some of the 
data and text is already familiar..


http://www.incompliancemag.com/index.php?option=com_contentview=articleid=739:using-ferrites-to-suppress-emicatid=26:designItemid=130

Carl
KM1H
Topband operators do not require adult beverages, just wire ones. 


All good topband ops know how to put up a beverage at night.
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Re: Topband: Thanks!

[Mike Waters]

Hi Charlie,

You are right, and you can thank Jim, K9YC for that. I used 14 turns of
CAT5 on a 2.4 OD #31 ferrite core, per his suggestion. Photo attached.

Out of all the info I have ever read on ferrite materials and common-mode
chokes --either in print or on the Web-- Jim's info at
http://audiosystemsgroup.com/RFI-Ham.pdf has been the most valuable to me.

73, Mike
www.w0btu.com

On Wed, May 22, 2013 at 12:34 AM, Charlie Cunningham 
charlie-cunning...@nc.rr.com wrote:

 I would think 31 material would be great for RF control and suppression on
 things like CAT5 cables, telephone circuits, audio circuits etc.!

 Regards,
 Charlie, K4OTV


 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike
 Waters
 Sent: Wednesday, May 22, 2013 1:01 AM
 To: topband
 Subject: Re: Topband: Thanks!

 That's true, but 31 material is the closest thing I've come to a magic
 cure here, for several applications in the past year! :-)

 It's the ONLY material that kept 75 meter RF from getting into my shack
 computer's CAT5 LAN cable (etc.), and it worked perfectly as a choke balun
 on a G5RV-type antenna I experimented with last year.

 31 almost ought to be one of the definitions of magic in the dictionary.
 :-)

 73, Mike
 www.w0btu.com

 On Tue, May 21, 2013 at 9:07 PM, Tom W8JI w...@w8ji.com wrote:

 
  31 isn't a magic cure-all, ...


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

Re: Topband: Thanks!

[Tom W8JI]

I think that 31 material is probably a good choice for cleaning RF from
wiring that isn't handling RF power and where there isn't much in the way 
of

shunt impedance for the choke to work against -like a line from an
electricity meter carrying a much as 480 VAC (530 VAC at 480 high-line).`


That line has shunt impedances. Almost everything does. A main area for 
shunting impedance is the entrance ground.


The individual wires couple together fairly tight, so even the hot wires 
have shunt impedance.


This is one of the reasons antenna systems, with system design flaws causing 
common mode issues, have better reception  (less noise) with improved 
grounding on the mains. The shunt impedance is as important as any series 
bead or choke string. The better the ground, the less important choke 
impedance is.


Another common point is downstream at the station. If the feeders have 
common mode from poor feed arrangements, reducing shunt impedance on the 
path from antenna feeders to power mains reduces noise.


Common mode chokes are part of a system.

Because I have a good entrance layout and cable bonding, just a single bead 
makes a large difference. If I had a sloppy arrangement with high shunt 
impedances, I could have fifty beads and not change much.


This is the problem with small antennas, or antennas with high common mode 
impedance. The antenna itself doesn't present much shunt impedance. The 
series part of the pi filter or attenuator formed by the shunt impedances 
and series beads or chokes is in a high impedance path, and has very little 
attenuation even with astronomical series impedances.


It is a system with huge variables if the variables are not controlled, not 
something that generally the same where one rule fits every system.


That's also an issue on high-speed digital circuits that can't tolerate 
much

in the way of shunt capacitance.


Not on individual lines, but when the lines are properly grouped they can 
have low shunt impedance for common mode and high shunt impedance for 
desired signal modes. Although we might not always think about it, we do 
that all the time in systems.



Not so sure about it as a balun on coax carrying much RF power!


Every different system has to be looked at as a unique system, but the best 
way to avoid troubles is to design feedpoints and equipment entrance points 
properly.  Proper basics are far better than randomly peppering a mess of a 
system with beads.


The nice thing is what we do for lightning also works for RF, and vice 
versa.


An air coil choke is just as good as beads when the system is planned. As a 
matter of fact, we can build a nearly perfect single band balun with no 
beads and no solenoid chokes at all. An 80 meter dipole with a feedline in 
air and a ground ~~40-80 feet from the antenna has virtually no common mode 
without any balun at all.  As a matter of fact, a balun could make it worse.


We need to think about the system more, and guess less.

73 Tom 


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

Re: Topband: Thanks!

[Charlie Cunningham]

All good and valid points, Tom!  Thanks!

Regards,
Charlie, K4OTV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI
Sent: Wednesday, May 22, 2013 9:35 AM
To: Charlie Cunningham; topband@contesting.com
Subject: Re: Topband: Thanks!

 I think that 31 material is probably a good choice for cleaning RF from
 wiring that isn't handling RF power and where there isn't much in the way 
 of
 shunt impedance for the choke to work against -like a line from an
 electricity meter carrying a much as 480 VAC (530 VAC at 480 high-line).`

That line has shunt impedances. Almost everything does. A main area for 
shunting impedance is the entrance ground.

The individual wires couple together fairly tight, so even the hot wires 
have shunt impedance.

This is one of the reasons antenna systems, with system design flaws causing

common mode issues, have better reception  (less noise) with improved 
grounding on the mains. The shunt impedance is as important as any series 
bead or choke string. The better the ground, the less important choke 
impedance is.

Another common point is downstream at the station. If the feeders have 
common mode from poor feed arrangements, reducing shunt impedance on the 
path from antenna feeders to power mains reduces noise.

Common mode chokes are part of a system.

Because I have a good entrance layout and cable bonding, just a single bead 
makes a large difference. If I had a sloppy arrangement with high shunt 
impedances, I could have fifty beads and not change much.

This is the problem with small antennas, or antennas with high common mode 
impedance. The antenna itself doesn't present much shunt impedance. The 
series part of the pi filter or attenuator formed by the shunt impedances 
and series beads or chokes is in a high impedance path, and has very little 
attenuation even with astronomical series impedances.

It is a system with huge variables if the variables are not controlled, not 
something that generally the same where one rule fits every system.

 That's also an issue on high-speed digital circuits that can't tolerate 
 much
 in the way of shunt capacitance.

Not on individual lines, but when the lines are properly grouped they can 
have low shunt impedance for common mode and high shunt impedance for 
desired signal modes. Although we might not always think about it, we do 
that all the time in systems.

 Not so sure about it as a balun on coax carrying much RF power!

Every different system has to be looked at as a unique system, but the best 
way to avoid troubles is to design feedpoints and equipment entrance points 
properly.  Proper basics are far better than randomly peppering a mess of a 
system with beads.

The nice thing is what we do for lightning also works for RF, and vice 
versa.

An air coil choke is just as good as beads when the system is planned. As a 
matter of fact, we can build a nearly perfect single band balun with no 
beads and no solenoid chokes at all. An 80 meter dipole with a feedline in 
air and a ground ~~40-80 feet from the antenna has virtually no common mode 
without any balun at all.  As a matter of fact, a balun could make it worse.

We need to think about the system more, and guess less.

73 Tom 

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

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

Re: Topband: Thanks!

[Tom W8JI]

These are not excellent 1:1 current baluns below about 75 MHz. Below 
that range, they are a lousy common mode choke, because they are 
inductive. Inductive chokes resonate with a line that is capacitive, so 
they actually increase the current. A line shorter than a quarter wave is 
capacitive; so is a line between a half wave and 3/4 wave. And so on. 
That's why we want a choke that is highly resistive -- the resistive 
component always reduces common mode current, which is the objective of a 
common mode choke (the so-called current balun.)



You may be confused, or I am. He asked about 31 mix beads:


Hi Folks;
Thanks a bunch, to all those who responded with source possibilities for 31 
mix toroids !  I will add a note here, after I actually make a purchase to 
designate the lucky victim of my small purchase.

73 Dean  W5PJR




31 materials has a Q of about 1 on 80 meters. This means a good part of the 
impedance is resistive.


While I don't beads are a good choice with large coax, only one pass can be 
made through the window with normal types of high power coax, I don't think 
the material itself is all that bad.


Also, attenuation has as much to do with grounding and wise engineering of 
common mode shunt impedances as it does choke impedance. Choke material is 
almost always a compromise between heat and Q at high power. For receiving, 
lossy common mode choke materials always work. Not so for transmitting.  One 
size will never come close to fitting all.


73 Tom 


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

Re: Topband: Thanks!

[Tom W8JI]

Well, I haven't used 31 mix material for common-mode chokes or current
baluns, because I didn't have any - but it would be my choice. I used 
higher

frequency material because I had plenty of it - some in substantial sizes


31 isn't a magic cure-all, just as no other single material is. One of the 
most difficult things in the world is designing something that fits systems 
with conflicting goals.


When power levels increase, or when systems have very high voltages 
impressed across the choke, a higher Q material often works better. Tuner 
baluns are an example where theoretically optimum common mode impedance is 
traded off for reducing heat. If a balun melts down, it is useless.


The balun that never gets hot is a short circuit or perfect lossless 
reactance. The balun that has immunity to resonance is a balun that will 
melt down with certain load impedances.


The ARRL still doesn't have the issue of baluns on the inputs of tuners 
correct, so we have a long way to go in public education. There was a 
discussion on the Elecraft reflector where someone just got it wrong in an 
analysis, and an ARRL staffer used the flawed design analysis to justify a 
Handbook tuner with poor balance design.


Every system has to be looked at as a system.

73 Tom 


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

Re: Topband: Thanks!

[Charlie Cunningham]

Well, I've wondered about the heating of 31 material because of the large
resistive term.

I've used higher frequency material (71 as I recall) because I had lots of
it in all shapes and sizes in Designer Kits and we used it a LOT of it to
reduce high-frequency emissions from electricity meter electronics on wiring
and cables that exited the meter. Nothing really to ground to on a meter.
The chassis is connected to one of the line phases!! Problematic for
external antennas, too!!

Charlie, K4OTV

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI
Sent: Tuesday, May 21, 2013 10:08 PM
To: topband@contesting.com
Subject: Re: Topband: Thanks!

 Well, I haven't used 31 mix material for common-mode chokes or current
 baluns, because I didn't have any - but it would be my choice. I used 
 higher
 frequency material because I had plenty of it - some in substantial sizes

31 isn't a magic cure-all, just as no other single material is. One of the 
most difficult things in the world is designing something that fits systems 
with conflicting goals.

When power levels increase, or when systems have very high voltages 
impressed across the choke, a higher Q material often works better. Tuner 
baluns are an example where theoretically optimum common mode impedance is 
traded off for reducing heat. If a balun melts down, it is useless.

The balun that never gets hot is a short circuit or perfect lossless 
reactance. The balun that has immunity to resonance is a balun that will 
melt down with certain load impedances.

The ARRL still doesn't have the issue of baluns on the inputs of tuners 
correct, so we have a long way to go in public education. There was a 
discussion on the Elecraft reflector where someone just got it wrong in an 
analysis, and an ARRL staffer used the flawed design analysis to justify a 
Handbook tuner with poor balance design.

Every system has to be looked at as a system.

73 Tom 

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

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

Re: Topband: Thanks!

[Charlie Cunningham]

Well, Tom

I think that 31 material is probably a good choice for cleaning RF from
wiring that isn't handling RF power and where there isn't much in the way of
shunt impedance for the choke to work against -like a line from an
electricity meter carrying a much as 480 VAC (530 VAC at 480 high-line).
That's also an issue on high-speed digital circuits that can't tolerate much
in the way of shunt capacitance.

Not so sure about it as a balun on coax carrying much RF power!

73
Charlie, K4OT V

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI
Sent: Tuesday, May 21, 2013 10:08 PM
To: topband@contesting.com
Subject: Re: Topband: Thanks!

 Well, I haven't used 31 mix material for common-mode chokes or current
 baluns, because I didn't have any - but it would be my choice. I used 
 higher
 frequency material because I had plenty of it - some in substantial sizes

31 isn't a magic cure-all, just as no other single material is. One of the 
most difficult things in the world is designing something that fits systems 
with conflicting goals.

When power levels increase, or when systems have very high voltages 
impressed across the choke, a higher Q material often works better. Tuner 
baluns are an example where theoretically optimum common mode impedance is 
traded off for reducing heat. If a balun melts down, it is useless.

The balun that never gets hot is a short circuit or perfect lossless 
reactance. The balun that has immunity to resonance is a balun that will 
melt down with certain load impedances.

The ARRL still doesn't have the issue of baluns on the inputs of tuners 
correct, so we have a long way to go in public education. There was a 
discussion on the Elecraft reflector where someone just got it wrong in an 
analysis, and an ARRL staffer used the flawed design analysis to justify a 
Handbook tuner with poor balance design.

Every system has to be looked at as a system.

73 Tom 

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

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

Re: Topband: Thanks!

[Mike Waters]

That's true, but 31 material is the closest thing I've come to a magic
cure here, for several applications in the past year! :-)

It's the ONLY material that kept 75 meter RF from getting into my shack
computer's CAT5 LAN cable (etc.), and it worked perfectly as a choke balun
on a G5RV-type antenna I experimented with last year.

31 almost ought to be one of the definitions of magic in the dictionary.
:-)

73, Mike
www.w0btu.com

On Tue, May 21, 2013 at 9:07 PM, Tom W8JI w...@w8ji.com wrote:


 31 isn't a magic cure-all, ...

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

Re: Topband: Thanks!

[Charlie Cunningham]

Good luck, Dean!!

I'm sure you can find what you need! (I've even thought about approaching  
Kreger Components about establishing a small dealership to serve the amateur 
community)  I think that Jim's comments about buying  box-sized lots to 
minimize damage, have merit, though.

Good luck in your quest - I'm sure that you can find just what you need!

Best regards,
Charlie, K4OTV
Charles Cunningham, Jr.  PE

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of 
dospi...@q.com
Sent: Saturday, May 18, 2013 9:38 AM
To: topband@contesting.com
Subject: Topband: Thanks!



  

Hi Folks; 

  

Thanks a bunch, to all those who responded with source possibilities for 31 mix 
toroids !  I will add a note here, after I actually make a purchase to 
designate the lucky victim of my small purchase. 



73 Dean  W5PJR 

Tijeras, NM 

  

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

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

Re: Topband: Thanks!

[Charlie Cunningham]

Hi, Dean

Well good luck in your hunt.

Over the years I've found many uses for various Fair-Rite cores at HF. If you 
get the larger beads/tubes thatwill fit over RG-213 etc. you can make excellent 
1:1 current baluns by slipping them over the cable before putting the connector 
on. You can hold them in place with wire-ties. The ferrite is completely 
impervious to weather as far as I can tell.

I've also used Fair-Rite cores to construct the input matching transformer in 
my home-brew 3-500Z amp and I've used smaller binocular cores to wind matchng 
transformers for 160 receiving loops.

So, many applications for the cores - not just on Topband!  :-)

Have a good afternoon!

Charlie, K4OTV

-Original Message-
From: dospi...@q.com [mailto:dospi...@q.com] 
Sent: Saturday, May 18, 2013 12:24 PM
To: Charlie Cunningham
Subject: Re: Topband: Thanks!


Hi Charlie:

Thanks for the infos and the good wishes.  Im looking at the fair-rite 
catalog and trying to come up with a good selection for experimentation when I 
run into RFI problems.

Not sure how much of a ham market there really is, outside of the lowbanders. I 
never hear anybody else complaining about it.  

I guess the buy bulk advice is good for somebody, but certainly didnt 
address my question. 

73 and TU again

Dean W5PJR
Tijeras, NM


- Original Message -
From: Charlie Cunningham charlie-cunning...@nc.rr.com
To: dospi...@q.com, topband@contesting.com
Sent: Saturday, May 18, 2013 10:17:18 AM
Subject: RE: Topband: Thanks!

Good luck, Dean!!

I'm sure you can find what you need! (I've even thought about approaching  
Kreger Components about establishing a small dealership to serve the amateur 
community)  I think that Jim's comments about buying  box-sized lots to 
minimize damage, have merit, though.

Good luck in your quest - I'm sure that you can find just what you need!

Best regards,
Charlie, K4OTV
Charles Cunningham, Jr.  PE

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of 
dospi...@q.com
Sent: Saturday, May 18, 2013 9:38 AM
To: topband@contesting.com
Subject: Topband: Thanks!



  

Hi Folks; 

  

Thanks a bunch, to all those who responded with source possibilities for 31 mix 
toroids !  I will add a note here, after I actually make a purchase to 
designate the lucky victim of my small purchase. 



73 Dean  W5PJR 

Tijeras, NM 

  

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

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