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Re: Balun Questions

Jim Allen
Ok, so this morning, I went out to the shack and whipped up a balun, from a G3TXQ design I found on the website of W5DXP.com.  It is coax wrapped around a ferrite core, with appropriate connectors in a plastic weathertight box.  I used RG8X coax, a 2.4" core, not sure exactly what mix, and 11 turns.

How do I test this device to get its properties, impedance at various frequencies, etc?  

It appears to function when I put it inline.  The KAT100 seems happy.  It produces a decent match on 40-10m using the 44' long rotating dipole at ~37' fed with 450 ohm twin lead.  I have no idea how efficient it might be, of course, if at all.

I still don't hear the VP8 much above the noise. :>(

73 de W6OGC Jim Allen

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Re: Balun Questions

Guy Olinger K2AV
On Saturday, February 6, 2016, Jim Allen <[hidden email]> wrote:

>  I used RG8X coax, a 2.4" core, not sure exactly what mix, and 11 turns.
>

There is a *huge* variation in core materials and performance specifics found
in the FT241 form factor.

It really matters what the actual material is. On 160 the variation in the
balun could be performance anywhere between fairly decent
and amazingly pathetic.

73, Guy K2AV

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Re: Balun Questions

Wes (N7WS)
In reply to this post by Jim Allen
If you're driving a 50 ohm load, then the cable wound around the core is just an
extension of the transmission line and has no impedance modifying effects.

The significant parameter is the common mode (CM) impedance. G3TXQ discusses a
way to measure it here: http://www.karinya.net/g3txq/chokes/#measurement

You can back into whether the CM is high enough by terminating each output with
a resistive load to ground and measuring the two output voltages and phases with
something like an HP8405 Vector Voltmeter.  Walt Maxwell, W2DU, discussed this
in his book, "Reflections II" (p, 21-8 thru 21-10)

On 2/6/2016 11:06 AM, Jim Allen wrote:

> Ok, so this morning, I went out to the shack and whipped up a balun, from a G3TXQ design I found on the website of W5DXP.com.  It is coax wrapped around a ferrite core, with appropriate connectors in a plastic weathertight box.  I used RG8X coax, a 2.4" core, not sure exactly what mix, and 11 turns.
>
> How do I test this device to get its properties, impedance at various frequencies, etc?
>
> It appears to function when I put it inline.  The KAT100 seems happy.  It produces a decent match on 40-10m using the 44' long rotating dipole at ~37' fed with 450 ohm twin lead.  I have no idea how efficient it might be, of course, if at all.
>
> I still don't hear the VP8 much above the noise. :>(
>
> 73 de W6OGC Jim Allen
>
> Sent from my iPad
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Re: Balun Questions

Bob McGraw - K4TAX
In reply to this post by Guy Olinger K2AV
I would have concern that long term usage of RG-8X, being foam core
dielectric material and bent in a tight radius, may allow the center
conductor to migrate to the inside radius of the bend.  The Minimum Bend
Radius for RG-8X is 2.50".     Thus the tight bend will allow the center
conductor to short to the shield.  A solid core dielectric coax such as
RG-303  is much preferred.

73
Bob, K4TAX



On 2/6/2016 1:22 PM, Guy Olinger K2AV wrote:

> On Saturday, February 6, 2016, Jim Allen <[hidden email]> wrote:
>
>>   I used RG8X coax, a 2.4" core, not sure exactly what mix, and 11 turns.
>>
> There is a *huge* variation in core materials and performance specifics found
> in the FT241 form factor.
>
> It really matters what the actual material is. On 160 the variation in the
> balun could be performance anywhere between fairly decent
> and amazingly pathetic.
>
> 73, Guy K2AV
>


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Re: Balun Questions

David Olean
Tell me about it! I made a 1/2 wave balun for a 432 yagi. I used Times FM-8
foam coax. (RG-8 sized with low loss foam dielectric) and it was bent in a U
shape that did not exceed the bending radius.  I tested it with a 700 watt
output amplifier and the VSWR went through the roof in under a second. The
coax center conductor drifted away from the center at the midway point of
the balun and caused the high VSWR. It did not short out, but was rendered
unuseable. I ended up making a 1/4 wave balun with copper pipe and a Delta
match. Don't use foam coax for high voltage either!

Dave K1WHS
----- Original Message -----
From: "Ron D'Eau Claire" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, February 06, 2016 10:33 PM
Subject: Re: [Elecraft] Balun Questions


> Bob makes an excellent point. I've seen cases where even "solid"
> dielectric
> did that over time because, after all, it is not really solid. The
> dielectric is plastic so the coax can be bent.
>
> All coax has a minimum bending radius specification. Specific data is
> available on line but, in general, RG58 size cable usually has a minimum
> radius of 1 to 1.5 inches (2.5 to 3.8 cm) and RG8 size cable has a minimum
> radius of at least 2 inches (5 cm). Note that is radius. If you curl the
> cable into a circle the minimum diameter of that circle should be at least
> twice that or 3 to 4 inches (7.5 to 10 cm).
>
> It's not something I've found especially critical in HF applications at
> least around my shack, but tighter bends, which may not actually cause a
> short (yet), alter the impedance as the center conductor migrates toward
> one
> side so it is no longer equally spaced within the shield. This can be a
> serious issue in microwave and even UHF installations.
>
> 73, Ron AC7AC
>
>
>
> -----Original Message-----
> I would have concern that long term usage of RG-8X, being foam core
> dielectric material and bent in a tight radius, may allow the center
> conductor to migrate to the inside radius of the bend.  The Minimum Bend
> Radius for RG-8X is 2.50".     Thus the tight bend will allow the center
> conductor to short to the shield.  A solid core dielectric coax such as
> RG-303  is much preferred.
>
> 73
> Bob, K4TAX
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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Re: Balun Questions

Jim Allen
In reply to this post by Jim Allen
Almost all of G3TXQ's tests on his website with ferrite core baluns involved RG58, so I figured RG8X would be even better.  I have a lot of it, and no RG58.

Luckily, these things are easy to work with, so if I ever have/want/need to change it, it's so easy even a lawyer can do it, 3 out of 5 tries, anyway.

I see also that Steve's test methods involve equipment I don't have or ever heard of!

Thanks for the inputs, men, and the off list e-mails, too.  At least I won't be as dumb for the rest of my life as I was last week.

73 de W6OGC Jim Allen

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Re: Balun Questions

Guy Olinger K2AV
In reply to this post by David Olean
If one wants a small 50 ohm coax that will take QRO with a very large
margin and was *designed* for bending and use in aircraft wiring harnesses
then use RG400 to wind around your core. RG400 uses a fine stranded
silvered copper center conductor that is more flexible than its Teflon
dielectric. It has a double shield made from silvered copper strands.

That's silvered strands whose silver sulphide patina or tarnish is
conductive as opposed to the green copper sulphate that separates copper
strands that have been water soaked.

Wind the coil form with RG59 to get the length and buy just what RG400 you
need. You can buy brand new RG400 by the foot.  With the Teflon dielectric
you can solder the RG400 without worrying about melting it.

Do it with the good stuff to start with and put it in your will.

73, Guy K2AV

On Saturday, February 6, 2016, Ron D'Eau Claire <[hidden email]> wrote:

> Bob makes an excellent point. I've seen cases where even "solid" dielectric
> did that over time because, after all, it is not really solid. The
> dielectric is plastic so the coax can be bent.
>
> All coax has a minimum bending radius specification. Specific data is
> available on line but, in general, RG58 size cable usually has a minimum
> radius of 1 to 1.5 inches (2.5 to 3.8 cm) and RG8 size cable has a minimum
> radius of at least 2 inches (5 cm). Note that is radius. If you curl the
> cable into a circle the minimum diameter of that circle should be at least
> twice that or 3 to 4 inches (7.5 to 10 cm).
>
> It's not something I've found especially critical in HF applications at
> least around my shack, but tighter bends, which may not actually cause a
> short (yet), alter the impedance as the center conductor migrates toward
> one
> side so it is no longer equally spaced within the shield. This can be a
> serious issue in microwave and even UHF installations.
>
> 73, Ron AC7AC
>
>
>
> -----Original Message-----
> I would have concern that long term usage of RG-8X, being foam core
> dielectric material and bent in a tight radius, may allow the center
> conductor to migrate to the inside radius of the bend.  The Minimum Bend
> Radius for RG-8X is 2.50".     Thus the tight bend will allow the center
> conductor to short to the shield.  A solid core dielectric coax such as
> RG-303  is much preferred.
>
> 73
> Bob, K4TAX
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email] <javascript:;>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email] <javascript:;>
>


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Re: Balun Questions

Robert Nobis - N7RJN
I have used RG303/U for chokes.  A bit smaller diameter than RG400 (0.170 versus 0.195 inches). RG303/U has a solid copper center conductor that is silver plated.  The shield for RG303 is also silver plated copper. The jacket is Class 9 Teflon. Also the dielectric material is teflon.

73,


Bob Nobis - N7RJN
[hidden email]


> On Feb 6, 2016, at 17:49, Guy Olinger K2AV <[hidden email]> wrote:
>
> If one wants a small 50 ohm coax that will take QRO with a very large
> margin and was *designed* for bending and use in aircraft wiring harnesses
> then use RG400 to wind around your core. RG400 uses a fine stranded
> silvered copper center conductor that is more flexible than its Teflon
> dielectric. It has a double shield made from silvered copper strands.
>
> That's silvered strands whose silver sulphide patina or tarnish is
> conductive as opposed to the green copper sulphate that separates copper
> strands that have been water soaked.
>
> Wind the coil form with RG59 to get the length and buy just what RG400 you
> need. You can buy brand new RG400 by the foot.  With the Teflon dielectric
> you can solder the RG400 without worrying about melting it.
>
> Do it with the good stuff to start with and put it in your will.
>
> 73, Guy K2AV
>
> On Saturday, February 6, 2016, Ron D'Eau Claire <[hidden email]> wrote:
>
>> Bob makes an excellent point. I've seen cases where even "solid" dielectric
>> did that over time because, after all, it is not really solid. The
>> dielectric is plastic so the coax can be bent.
>>
>> All coax has a minimum bending radius specification. Specific data is
>> available on line but, in general, RG58 size cable usually has a minimum
>> radius of 1 to 1.5 inches (2.5 to 3.8 cm) and RG8 size cable has a minimum
>> radius of at least 2 inches (5 cm). Note that is radius. If you curl the
>> cable into a circle the minimum diameter of that circle should be at least
>> twice that or 3 to 4 inches (7.5 to 10 cm).
>>
>> It's not something I've found especially critical in HF applications at
>> least around my shack, but tighter bends, which may not actually cause a
>> short (yet), alter the impedance as the center conductor migrates toward
>> one
>> side so it is no longer equally spaced within the shield. This can be a
>> serious issue in microwave and even UHF installations.
>>
>> 73, Ron AC7AC
>>
>>
>>
>> -----Original Message-----
>> I would have concern that long term usage of RG-8X, being foam core
>> dielectric material and bent in a tight radius, may allow the center
>> conductor to migrate to the inside radius of the bend.  The Minimum Bend
>> Radius for RG-8X is 2.50".     Thus the tight bend will allow the center
>> conductor to short to the shield.  A solid core dielectric coax such as
>> RG-303  is much preferred.
>>
>> 73
>> Bob, K4TAX
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email] <javascript:;>
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email] <javascript:;>
>>
>
>
> --
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Re: Balun Questions

Bob McGraw - K4TAX
Yep, good stuff.  Be sure of your budget before buying a roll.  It is a
bit pricey.  Handles legal limit HF power with a reasonable SWR.

73
Bob, K4TAX



On 2/6/2016 7:10 PM, Robert Nobis wrote:

> I have used RG303/U for chokes.  A bit smaller diameter than RG400 (0.170 versus 0.195 inches). RG303/U has a solid copper center conductor that is silver plated.  The shield for RG303 is also silver plated copper. The jacket is Class 9 Teflon. Also the dielectric material is teflon.
>
> 73,
>
>
> Bob Nobis - N7RJN
> [hidden email]
>
>
>> On Feb 6, 2016, at 17:49, Guy Olinger K2AV <[hidden email]> wrote:
>>
>> If one wants a small 50 ohm coax that will take QRO with a very large
>> margin and was *designed* for bending and use in aircraft wiring harnesses
>> then use RG400 to wind around your core. RG400 uses a fine stranded
>> silvered copper center conductor that is more flexible than its Teflon
>> dielectric. It has a double shield made from silvered copper strands.
>>
>> That's silvered strands whose silver sulphide patina or tarnish is
>> conductive as opposed to the green copper sulphate that separates copper
>> strands that have been water soaked.
>>
>> Wind the coil form with RG59 to get the length and buy just what RG400 you
>> need. You can buy brand new RG400 by the foot.  With the Teflon dielectric
>> you can solder the RG400 without worrying about melting it.
>>
>> Do it with the good stuff to start with and put it in your will.
>>
>> 73, Guy K2AV
>>
>> On Saturday, February 6, 2016, Ron D'Eau Claire <[hidden email]> wrote:
>>
>>> Bob makes an excellent point. I've seen cases where even "solid" dielectric
>>> did that over time because, after all, it is not really solid. The
>>> dielectric is plastic so the coax can be bent.
>>>
>>> All coax has a minimum bending radius specification. Specific data is
>>> available on line but, in general, RG58 size cable usually has a minimum
>>> radius of 1 to 1.5 inches (2.5 to 3.8 cm) and RG8 size cable has a minimum
>>> radius of at least 2 inches (5 cm). Note that is radius. If you curl the
>>> cable into a circle the minimum diameter of that circle should be at least
>>> twice that or 3 to 4 inches (7.5 to 10 cm).
>>>
>>> It's not something I've found especially critical in HF applications at
>>> least around my shack, but tighter bends, which may not actually cause a
>>> short (yet), alter the impedance as the center conductor migrates toward
>>> one
>>> side so it is no longer equally spaced within the shield. This can be a
>>> serious issue in microwave and even UHF installations.
>>>
>>> 73, Ron AC7AC
>>>
>>>
>>>
>>> -----Original Message-----
>>> I would have concern that long term usage of RG-8X, being foam core
>>> dielectric material and bent in a tight radius, may allow the center
>>> conductor to migrate to the inside radius of the bend.  The Minimum Bend
>>> Radius for RG-8X is 2.50".     Thus the tight bend will allow the center
>>> conductor to short to the shield.  A solid core dielectric coax such as
>>> RG-303  is much preferred.
>>>
>>> 73
>>> Bob, K4TAX
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email] <javascript:;>
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email] <javascript:;>
>>>
>>
>> --
>> Sent via Gmail Mobile on my iPhone
>> ______________________________________________________________
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>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
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>> Please help support this email list: http://www.qsl.net/donate.html
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>>
> ______________________________________________________________
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Re: Balun Questions

Robert Nobis - N7RJN
Bob,

Yes, it is a bit expensive: $2.91 per foot from “The Wireman” plus shipping.  (For lengths under 100 feet.)

73,


Bob Nobis - N7RJN
[hidden email]


> On Feb 6, 2016, at 18:21, Bob McGraw K4TAX <[hidden email]> wrote:
>
> Yep, good stuff.  Be sure of your budget before buying a roll.  It is a bit pricey.  Handles legal limit HF power with a reasonable SWR.
>
> 73
> Bob, K4TAX
>
>
>
> On 2/6/2016 7:10 PM, Robert Nobis wrote:
>> I have used RG303/U for chokes.  A bit smaller diameter than RG400 (0.170 versus 0.195 inches). RG303/U has a solid copper center conductor that is silver plated.  The shield for RG303 is also silver plated copper. The jacket is Class 9 Teflon. Also the dielectric material is teflon.
>>
>> 73,
>>
>>
>> Bob Nobis - N7RJN
>> [hidden email]
>>
>>
>>> On Feb 6, 2016, at 17:49, Guy Olinger K2AV <[hidden email]> wrote:
>>>
>>> If one wants a small 50 ohm coax that will take QRO with a very large
>>> margin and was *designed* for bending and use in aircraft wiring harnesses
>>> then use RG400 to wind around your core. RG400 uses a fine stranded
>>> silvered copper center conductor that is more flexible than its Teflon
>>> dielectric. It has a double shield made from silvered copper strands.
>>>
>>> That's silvered strands whose silver sulphide patina or tarnish is
>>> conductive as opposed to the green copper sulphate that separates copper
>>> strands that have been water soaked.
>>>
>>> Wind the coil form with RG59 to get the length and buy just what RG400 you
>>> need. You can buy brand new RG400 by the foot.  With the Teflon dielectric
>>> you can solder the RG400 without worrying about melting it.
>>>
>>> Do it with the good stuff to start with and put it in your will.
>>>
>>> 73, Guy K2AV
>>>
>>> On Saturday, February 6, 2016, Ron D'Eau Claire <[hidden email]> wrote:
>>>
>>>> Bob makes an excellent point. I've seen cases where even "solid" dielectric
>>>> did that over time because, after all, it is not really solid. The
>>>> dielectric is plastic so the coax can be bent.
>>>>
>>>> All coax has a minimum bending radius specification. Specific data is
>>>> available on line but, in general, RG58 size cable usually has a minimum
>>>> radius of 1 to 1.5 inches (2.5 to 3.8 cm) and RG8 size cable has a minimum
>>>> radius of at least 2 inches (5 cm). Note that is radius. If you curl the
>>>> cable into a circle the minimum diameter of that circle should be at least
>>>> twice that or 3 to 4 inches (7.5 to 10 cm).
>>>>
>>>> It's not something I've found especially critical in HF applications at
>>>> least around my shack, but tighter bends, which may not actually cause a
>>>> short (yet), alter the impedance as the center conductor migrates toward
>>>> one
>>>> side so it is no longer equally spaced within the shield. This can be a
>>>> serious issue in microwave and even UHF installations.
>>>>
>>>> 73, Ron AC7AC
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> I would have concern that long term usage of RG-8X, being foam core
>>>> dielectric material and bent in a tight radius, may allow the center
>>>> conductor to migrate to the inside radius of the bend.  The Minimum Bend
>>>> Radius for RG-8X is 2.50".     Thus the tight bend will allow the center
>>>> conductor to short to the shield.  A solid core dielectric coax such as
>>>> RG-303  is much preferred.
>>>>
>>>> 73
>>>> Bob, K4TAX
>>>>
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email] <javascript:;>
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email] <javascript:;>
>>>>
>>>
>>> --
>>> Sent via Gmail Mobile on my iPhone
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
>
>
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Re: Balun Questions

Wes (N7WS)
In reply to this post by Guy Olinger K2AV
On oft repeated myth.

See: http://k6mhe.com/n7ws/Plating.pdf


On 2/6/2016 5:49 PM, Guy Olinger K2AV wrote:
>
> That's silvered strands whose silver sulphide patina or tarnish is
> conductive as opposed to the green copper sulphate that separates copper
> strands that have been water soaked.
>
>

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Re: Balun Questions

Jim Brown-10
In reply to this post by Jim Allen
On Sat,2/6/2016 4:33 PM, Jim Allen wrote:
> Almost all of G3TXQ's tests on his website with ferrite core baluns involved RG58, so I figured RG8X would be even better.  I have a lot of it, and no RG58.

Did you study the material on my website? My measurement method is
clearly described in several of the publications, including the RFI
tutorial, the AES Paper, and the Power Point for talks I've done for
several ham clubs and conventions. The equipment consists of an HP
Generator and HP Spectrum Analyzer (which was used as a terminated RF
voltmeter).

My work, and its publication precedes G3TXQ's by at least five years.
His work is clearly inspired by mine (and I would think by W1HIS's), yet
he fails to credit either of us. All of my writing credits others who
have made important contributions on the topic I'm writing about. I did,
for example, reference work and texts by Henry Ott, Clayton Paul, W1HIS,
E. C. Snelling, Neil Muncy, Bill Whitlock, Jerry Sevick, and Doug DeMaw
in the RFI tutorial.

The "Cookbook" that is part of my RFI tutorial is based directly on the
measured data that is discussed throughout the tutorial and summarized
in Appendix One.

73, Jim K9YC
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Re: Balun Questions

Guy Olinger K2AV
In reply to this post by Robert Nobis - N7RJN
RG303 is not rated for the tight bends.  RG400 with its fine stranded
center conductor is rated for corner bends in aircraft wiring harnesses and
will not deform the dielectric within the bends. I would not wind any solid
center conductor coax on a toroid.

I would only buy cut lengths of RG400 after the lengths for a project are
known. Some number of such suppliers on eBay. One currently listed at 1.98
per foot:
http://www.ebay.com/itm/RG400-Coaxial-Cable-Mil-spec-by-the-ft-US-supplier-/251260159394?hash=item3a8045c5a2:g:WpAAAOxy43FRafUe

True it ain't ham cheep. The good stuff that lasts and lasts almost never
is. Back in the early days of eBay I came by a 142' length of RG400 for
$25. That's $0.178  a foot  I also came by bundles of miscellaneous 6 foot
to 15 foot jumpers with various connectors on end for similar ridiculous
low prices per foot.

The silvered copper strands stand up to migration of dampness in a way not
possible with same size copper strands minus the silvering. I have
*measured* the dry RF resistance at 1.83 MHz of a 67 foot length of
corroded #14 stranded plain copper at 62 ohms. When new this wire had
resistance at RF of less than an ohm. I have never found the silvered
copper equivalent in anything remotely approaching that degraded state.

RG400 wound on the proper core for the job will last a lifetime.

73, Guy K2AV

On Saturday, February 6, 2016, Robert Nobis <[hidden email]> wrote:

> I have used RG303/U for chokes.  A bit smaller diameter than RG400 (0.170
> versus 0.195 inches). RG303/U has a solid copper center conductor that is
> silver plated.  The shield for RG303 is also silver plated copper. The
> jacket is Class 9 Teflon. Also the dielectric material is teflon.
>
> 73,
>
>
> Bob Nobis - N7RJN
> [hidden email]
>
>
> > On Feb 6, 2016, at 17:49, Guy Olinger K2AV <[hidden email]> wrote:
> >
> > If one wants a small 50 ohm coax that will take QRO with a very large
> > margin and was *designed* for bending and use in aircraft wiring
> harnesses
> > then use RG400 to wind around your core. RG400 uses a fine stranded
> > silvered copper center conductor that is more flexible than its Teflon
> > dielectric. It has a double shield made from silvered copper strands.
> >
>
>
>
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Re: Balun Questions

Robert Nobis - N7RJN
Guy,

After reviewing specs from several manufacturers, the “recommended” minimum bend radius for RG303 and RG400 is essentially the same at 1.0 inches.  

73,



Bob Nobis - N7RJN
[hidden email]


> On Feb 6, 2016, at 23:07, Guy Olinger K2AV <[hidden email]> wrote:
>
> RG303 is not rated for the tight bends.  RG400 with its fine stranded center conductor is rated for corner bends in aircraft wiring harnesses and will not deform the dielectric within the bends. I would not wind any solid center conductor coax on a toroid.
>
> I would only buy cut lengths of RG400 after the lengths for a project are known. Some number of such suppliers on eBay. One currently listed at 1.98 per foot: http://www.ebay.com/itm/RG400-Coaxial-Cable-Mil-spec-by-the-ft-US-supplier-/251260159394?hash=item3a8045c5a2:g:WpAAAOxy43FRafUe <http://www.ebay.com/itm/RG400-Coaxial-Cable-Mil-spec-by-the-ft-US-supplier-/251260159394?hash=item3a8045c5a2:g:WpAAAOxy43FRafUe>
>
> True it ain't ham cheep. The good stuff that lasts and lasts almost never is. Back in the early days of eBay I came by a 142' length of RG400 for $25. That's $0.178  a foot  I also came by bundles of miscellaneous 6 foot to 15 foot jumpers with various connectors on end for similar ridiculous low prices per foot.
>
> The silvered copper strands stand up to migration of dampness in a way not possible with same size copper strands minus the silvering. I have *measured* the dry RF resistance at 1.83 MHz of a 67 foot length of corroded #14 stranded plain copper at 62 ohms. When new this wire had resistance at RF of less than an ohm. I have never found the silvered copper equivalent in anything remotely approaching that degraded state.
>
> RG400 wound on the proper core for the job will last a lifetime.
>
> 73, Guy K2AV
>
> On Saturday, February 6, 2016, Robert Nobis <[hidden email] <>> wrote:
> I have used RG303/U for chokes.  A bit smaller diameter than RG400 (0.170 versus 0.195 inches). RG303/U has a solid copper center conductor that is silver plated.  The shield for RG303 is also silver plated copper. The jacket is Class 9 Teflon. Also the dielectric material is teflon.
>
> 73,
>
>
> Bob Nobis - N7RJN
> [hidden email] <>
>
>
> > On Feb 6, 2016, at 17:49, Guy Olinger K2AV <[hidden email] <>> wrote:
> >
> > If one wants a small 50 ohm coax that will take QRO with a very large
> > margin and was *designed* for bending and use in aircraft wiring harnesses
> > then use RG400 to wind around your core. RG400 uses a fine stranded
> > silvered copper center conductor that is more flexible than its Teflon
> > dielectric. It has a double shield made from silvered copper strands.
> >
>
>

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Re: Balun Questions

Victor Rosenthal 4X6GP
In reply to this post by Wes (N7WS)
Wow, that is eye opening! I always thought I was just lazy/cheap when I merely polished my amplifier tank coils and sprayed them with clear plastic (Krylon), but it seems I was doing the right thing after all.

Vic 4X6GP/K2VCO

> On 7 Feb 2016, at 3:48 AM, Wes (N7WS) <[hidden email]> wrote:
>
> On oft repeated myth.
>
> See: http://k6mhe.com/n7ws/Plating.pdf
>
>
>> On 2/6/2016 5:49 PM, Guy Olinger K2AV wrote:
>>
>> That's silvered strands whose silver sulphide patina or tarnish is
>> conductive as opposed to the green copper sulphate that separates copper
>> strands that have been water soaked.
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
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Re: Balun Questions

Wes (N7WS)
In reply to this post by Jim Brown-10
I can second Jim's concern about have one's work usurped by another.  I can
recall Googling a topic and having a paper come up on some Canadian's website
that appeared to be written by him but in fact was my ladderline paper.  I
emailed him and asked him nicely to remove it and simply link to my site. He
refused to do so, so I contacted his ISP and made them aware that he was
violating their TOS.  I guess he gave them a ration of crap so they closed his
account.

Bill Orr had my noise blanker circuit in his Handbook for years without me even
knowing about it until a friend mentioned it.  Of course, Ham Radio Magazine
held copyright and I suppose gave him permission but it would have been nice to
know.  It would have been even nicer to have received a copy.

Another example: A good friend of mine who is a stunning photographer
https://www.flickr.com/photos/gauchocat/ had someone tell him, "Hey Glenn, I saw
your photo in Audubon Magazine."  You guessed it, downloaded from Flickr.

Jim does excellent work; he should get credit for it.


On 2/6/2016 10:35 PM, Jim Brown wrote:

> On Sat,2/6/2016 4:33 PM, Jim Allen wrote:
>> Almost all of G3TXQ's tests on his website with ferrite core baluns involved
>> RG58, so I figured RG8X would be even better.  I have a lot of it, and no RG58.
>
> Did you study the material on my website? My measurement method is clearly
> described in several of the publications, including the RFI tutorial, the AES
> Paper, and the Power Point for talks I've done for several ham clubs and
> conventions. The equipment consists of an HP Generator and HP Spectrum
> Analyzer (which was used as a terminated RF voltmeter).
>
> My work, and its publication precedes G3TXQ's by at least five years. His work
> is clearly inspired by mine (and I would think by W1HIS's), yet he fails to
> credit either of us. All of my writing credits others who have made important
> contributions on the topic I'm writing about. I did, for example, reference
> work and texts by Henry Ott, Clayton Paul, W1HIS, E. C. Snelling, Neil Muncy,
> Bill Whitlock, Jerry Sevick, and Doug DeMaw in the RFI tutorial.
>
> The "Cookbook" that is part of my RFI tutorial is based directly on the
> measured data that is discussed throughout the tutorial and summarized in
> Appendix One.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Re: Balun Questions

Pete Michaelis - N8TR
In reply to this post by Guy Olinger K2AV
At 01:07 AM 2/7/2016, K2AV wrote:

>I also came by bundles of miscellaneous 6 foot to 15 foot jumpers with
>various connectors on end for similar ridiculous low prices per foot.

In the last few years I have found similar RG400 jumpers at the Dayton
Hamvention at quite reasonable prices.  Since I use RG400 exclusively
for making chokes, short lengths are fine.

73, Pete - N8TR

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Re: Balun Questions

Chuck - AE4CW
In reply to this post by Guy Olinger K2AV
At hamfests around the Southeast, surplus RG400 is often found in terminated cables (usually BNC or N) in lengths up to around 20 feet.  The price I've paid is always less than $1.00 per foot, sometimes much less.  I've used it to make dozens of RF chokes (1:1 baluns).  The small size of RG400 allows the use of a single medium to large clamp-on #31 ferrite that works effectively from 10-160M, conditioned by the number of turns.  The large snap-on ferrite will accommodate 10-12 turns; the medium snap-on will handle 5-6 turns.  Jim, K9YC's tutorials are excellent.  Consult the Fair-Rite website for additional technical data.

BTW, the Teflon dielectric allows easy soldering in PL-259s with RG-58 reducers without any fear of melting the dielectric.
---
Chuck, AE4CW

-----Original Message-----
From: Guy Olinger K2AV [mailto:[hidden email]]
Sent: Sunday, February 07, 2016 01:08
To: Robert Nobis <[hidden email]>
Cc: [hidden email]; Ron D'Eau Claire <[hidden email]>; Guy Olinger K2AV <[hidden email]>
Subject: Re: [Elecraft] Balun Questions

RG303 is not rated for the tight bends.  RG400 with its fine stranded center conductor is rated for corner bends in aircraft wiring harnesses and will not deform the dielectric within the bends. I would not wind any solid center conductor coax on a toroid.

I would only buy cut lengths of RG400 after the lengths for a project are known. Some number of such suppliers on eBay. One currently listed at 1.98 per foot:
http://www.ebay.com/itm/RG400-Coaxial-Cable-Mil-spec-by-the-ft-US-supplier-/251260159394?hash=item3a8045c5a2:g:WpAAAOxy43FRafUe

True it ain't ham cheep. The good stuff that lasts and lasts almost never is. Back in the early days of eBay I came by a 142' length of RG400 for $25. That's $0.178  a foot  I also came by bundles of miscellaneous 6 foot to 15 foot jumpers with various connectors on end for similar ridiculous low prices per foot.

The silvered copper strands stand up to migration of dampness in a way not possible with same size copper strands minus the silvering. I have
*measured* the dry RF resistance at 1.83 MHz of a 67 foot length of corroded #14 stranded plain copper at 62 ohms. When new this wire had resistance at RF of less than an ohm. I have never found the silvered copper equivalent in anything remotely approaching that degraded state.

RG400 wound on the proper core for the job will last a lifetime.

73, Guy K2AV

On Saturday, February 6, 2016, Robert Nobis <[hidden email]> wrote:

> I have used RG303/U for chokes.  A bit smaller diameter than RG400
> (0.170 versus 0.195 inches). RG303/U has a solid copper center
> conductor that is silver plated.  The shield for RG303 is also silver
> plated copper. The jacket is Class 9 Teflon. Also the dielectric material is teflon.
>
> 73,
>
>
> Bob Nobis - N7RJN
> [hidden email]
>
>
> > On Feb 6, 2016, at 17:49, Guy Olinger K2AV <[hidden email]> wrote:
> >
> > If one wants a small 50 ohm coax that will take QRO with a very
> > large margin and was *designed* for bending and use in aircraft
> > wiring
> harnesses
> > then use RG400 to wind around your core. RG400 uses a fine stranded
> > silvered copper center conductor that is more flexible than its
> > Teflon dielectric. It has a double shield made from silvered copper strands.
> >
>
>
>


______________________________________________________________
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Post: mailto:[hidden email]

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---
Chuck, AE4CW
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Re: Balun Questions

Elecraft mailing list
SORRY, but the min static bending radius for RG-303 is 25 mm and RG-400 is 35 mm.  For torroid wrap which is better?????
Mel, K6KBE


      From: Chuck Catledge <[hidden email]>
 To: 'Guy Olinger K2AV' <[hidden email]>; 'Robert Nobis' <[hidden email]>
Cc: [hidden email]; 'Ron D'Eau Claire' <[hidden email]>
 Sent: Sunday, February 7, 2016 2:31 PM
 Subject: Re: [Elecraft] Balun Questions
   
At hamfests around the Southeast, surplus RG400 is often found in terminated cables (usually BNC or N) in lengths up to around 20 feet.  The price I've paid is always less than $1.00 per foot, sometimes much less.  I've used it to make dozens of RF chokes (1:1 baluns).  The small size of RG400 allows the use of a single medium to large clamp-on #31 ferrite that works effectively from 10-160M, conditioned by the number of turns.  The large snap-on ferrite will accommodate 10-12 turns; the medium snap-on will handle 5-6 turns.  Jim, K9YC's tutorials are excellent.  Consult the Fair-Rite website for additional technical data.

BTW, the Teflon dielectric allows easy soldering in PL-259s with RG-58 reducers without any fear of melting the dielectric.
---
Chuck, AE4CW

-----Original Message-----
From: Guy Olinger K2AV [mailto:[hidden email]]
Sent: Sunday, February 07, 2016 01:08
To: Robert Nobis <[hidden email]>
Cc: [hidden email]; Ron D'Eau Claire <[hidden email]>; Guy Olinger K2AV <[hidden email]>
Subject: Re: [Elecraft] Balun Questions

RG303 is not rated for the tight bends.  RG400 with its fine stranded center conductor is rated for corner bends in aircraft wiring harnesses and will not deform the dielectric within the bends. I would not wind any solid center conductor coax on a toroid.

I would only buy cut lengths of RG400 after the lengths for a project are known. Some number of such suppliers on eBay. One currently listed at 1.98 per foot:
http://www.ebay.com/itm/RG400-Coaxial-Cable-Mil-spec-by-the-ft-US-supplier-/251260159394?hash=item3a8045c5a2:g:WpAAAOxy43FRafUe

True it ain't ham cheep. The good stuff that lasts and lasts almost never is. Back in the early days of eBay I came by a 142' length of RG400 for $25. That's $0.178  a foot  I also came by bundles of miscellaneous 6 foot to 15 foot jumpers with various connectors on end for similar ridiculous low prices per foot.

The silvered copper strands stand up to migration of dampness in a way not possible with same size copper strands minus the silvering. I have
*measured* the dry RF resistance at 1.83 MHz of a 67 foot length of corroded #14 stranded plain copper at 62 ohms. When new this wire had resistance at RF of less than an ohm. I have never found the silvered copper equivalent in anything remotely approaching that degraded state.

RG400 wound on the proper core for the job will last a lifetime.

73, Guy K2AV

On Saturday, February 6, 2016, Robert Nobis <[hidden email]> wrote:

> I have used RG303/U for chokes.  A bit smaller diameter than RG400
> (0.170 versus 0.195 inches). RG303/U has a solid copper center
> conductor that is silver plated.  The shield for RG303 is also silver
> plated copper. The jacket is Class 9 Teflon. Also the dielectric material is teflon.
>
> 73,
>
>
> Bob Nobis - N7RJN
> [hidden email]
>
>
> > On Feb 6, 2016, at 17:49, Guy Olinger K2AV <[hidden email]> wrote:
> >
> > If one wants a small 50 ohm coax that will take QRO with a very
> > large margin and was *designed* for bending and use in aircraft
> > wiring
> harnesses
> > then use RG400 to wind around your core. RG400 uses a fine stranded
> > silvered copper center conductor that is more flexible than its
> > Teflon dielectric. It has a double shield made from silvered copper strands.
> >
>
>
>


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Re: Balun Questions

Robert Nobis - N7RJN
Mel,

I have seen comparable specs on RG303 versus RG400, however, some cable manufacturers have specified a larger bending radius for both cables. Not sure why?

I wonder if anyone has actually run tests of coax showing the real impact of bending with a small radius, comparable to what one would see in a typical common mode choke?

73

Bob Nobis - N7RJN
[hidden email]


> On Feb 7, 2016, at 15:53, Mel Farrer <[hidden email]> wrote:
>
> SORRY, but the min static bending radius for RG-303 is 25 mm and RG-400 is 35 mm.  For torroid wrap which is better?????
>
> Mel, K6KBE
>
>
> From: Chuck Catledge <[hidden email]>
> To: 'Guy Olinger K2AV' <[hidden email]>; 'Robert Nobis' <[hidden email]>
> Cc: [hidden email]; 'Ron D'Eau Claire' <[hidden email]>
> Sent: Sunday, February 7, 2016 2:31 PM
> Subject: Re: [Elecraft] Balun Questions
>
> At hamfests around the Southeast, surplus RG400 is often found in terminated cables (usually BNC or N) in lengths up to around 20 feet.  The price I've paid is always less than $1.00 per foot, sometimes much less.  I've used it to make dozens of RF chokes (1:1 baluns).  The small size of RG400 allows the use of a single medium to large clamp-on #31 ferrite that works effectively from 10-160M, conditioned by the number of turns.  The large snap-on ferrite will accommodate 10-12 turns; the medium snap-on will handle 5-6 turns.  Jim, K9YC's tutorials are excellent.  Consult the Fair-Rite website for additional technical data.
>
> BTW, the Teflon dielectric allows easy soldering in PL-259s with RG-58 reducers without any fear of melting the dielectric.
> ---
> Chuck, AE4CW
>
> -----Original Message-----
> From: Guy Olinger K2AV [mailto:[hidden email] <mailto:[hidden email]>]
> Sent: Sunday, February 07, 2016 01:08
> To: Robert Nobis <[hidden email] <mailto:[hidden email]>>
> Cc: [hidden email] <mailto:[hidden email]>; Ron D'Eau Claire <[hidden email] <mailto:[hidden email]>>; Guy Olinger K2AV <[hidden email] <mailto:[hidden email]>>
> Subject: Re: [Elecraft] Balun Questions
>
> RG303 is not rated for the tight bends.  RG400 with its fine stranded center conductor is rated for corner bends in aircraft wiring harnesses and will not deform the dielectric within the bends. I would not wind any solid center conductor coax on a toroid.
>
> I would only buy cut lengths of RG400 after the lengths for a project are known. Some number of such suppliers on eBay. One currently listed at 1.98 per foot:
> http://www.ebay.com/itm/RG400-Coaxial-Cable-Mil-spec-by-the-ft-US-supplier-/251260159394?hash=item3a8045c5a2:g:WpAAAOxy43FRafUe <http://www.ebay.com/itm/RG400-Coaxial-Cable-Mil-spec-by-the-ft-US-supplier-/251260159394?hash=item3a8045c5a2:g:WpAAAOxy43FRafUe>
>
> True it ain't ham cheep. The good stuff that lasts and lasts almost never is. Back in the early days of eBay I came by a 142' length of RG400 for $25. That's $0.178  a foot  I also came by bundles of miscellaneous 6 foot to 15 foot jumpers with various connectors on end for similar ridiculous low prices per foot.
>
> The silvered copper strands stand up to migration of dampness in a way not possible with same size copper strands minus the silvering. I have
> *measured* the dry RF resistance at 1.83 MHz of a 67 foot length of corroded #14 stranded plain copper at 62 ohms. When new this wire had resistance at RF of less than an ohm. I have never found the silvered copper equivalent in anything remotely approaching that degraded state.
>
> RG400 wound on the proper core for the job will last a lifetime.
>
> 73, Guy K2AV
>
> On Saturday, February 6, 2016, Robert Nobis <[hidden email] <mailto:[hidden email]>> wrote:
>
> > I have used RG303/U for chokes.  A bit smaller diameter than RG400
> > (0.170 versus 0.195 inches). RG303/U has a solid copper center
> > conductor that is silver plated.  The shield for RG303 is also silver
> > plated copper. The jacket is Class 9 Teflon. Also the dielectric material is teflon.
> >
> > 73,
> >
> >
> > Bob Nobis - N7RJN
> > [hidden email] <mailto:[hidden email]>
> >
> >
> > > On Feb 6, 2016, at 17:49, Guy Olinger K2AV <[hidden email] <mailto:[hidden email]>> wrote:
> > >
> > > If one wants a small 50 ohm coax that will take QRO with a very
> > > large margin and was *designed* for bending and use in aircraft
> > > wiring
> > harnesses
> > > then use RG400 to wind around your core. RG400 uses a fine stranded
> > > silvered copper center conductor that is more flexible than its
> > > Teflon dielectric. It has a double shield made from silvered copper strands.
> > >
> >
> >
> >
>
>
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