[CTSARA] PTFE tubing for copper wire used for 49:1 balun

[Ilan Grosman]

Hi Steve,

I meant to overbuild in terms of using 52 cores versus 43 type, and follow
your design. Thanks for saving me the costs of the unnecessary components.


Ilan




On Tue, Dec 3, 2019 at 8:54 AM Steve Dick <sbdick at optonline.net> wrote:

> Ilan, I have not seen any problems from anyone, not even once in Steve
> Ellingtons’s facebook group, when using 500W-1kW using the three core
> FT240-52s and no teflon tape on the cores or PTFE tubing on the wires.  The
> secondary turns are pretty separated, and the “crossover” in the middle of
> the secondary keeps the high voltage output away from the grounded primary
> side. The bigger problem might be core heating on 80 meters for high duty
> cycle mode like CW at high power.  SSB -  no problem.  Digital modes –
> shouldn’t be using high power anyway
>
> *From:* Ilan Grosman <ilan.m.grosman at gmail.com>
> *Sent:* Monday, December 02, 2019 10:26 PM
> *To:* Steve Dick <sbdick at optonline.net>
> *Cc:* ctsara Mailman <ctsara at mailman.qth.net>
> *Subject:* Re: [CTSARA] PTFE tubing for copper wire used for 49:1 balun
>
> Thanks Steve for clarifying. Your deck on the EFHW is the authoritative
> and best source I am following for materials and the build. I like that you
> put in not only the how, but the why and list of materials to build. I will
> be using the 3 52 cores as you suggested, and 12 AWG transformer wire. Also
> have the capacitor for the transformer (100pF) and in the middle of the
> antenna another capacitor (330 pF) as Steve Ellington is suggesting in his
> Facebook group on that type of antenna.
>
> At this point I am running only 100W but don't want to change
> configuration when/if I move to higher wattage, and there didn't seem to be
> a disadvantage to overbuild it from your deck other than cost of 52 versus
> 43 cores.
>
> Ilan
>
>
>
>
> On Mon, Dec 2, 2019 at 4:33 PM Steve Dick <sbdick at optonline.net> wrote:
>
>> Hi Elan. How much power are you running?  PTFE tubes are probably
>> unnecessary and can do more harm than good when building 49:1
>> transformers
>> (presumably for use with an end-fed halfwave antenna?)  For 49:1
>> transformers, they will increase leakage inductances and degrade
>> performance
>> on the higher bands, especially on 10 meters.  They are great when you
>> have
>> smaller turns ratio baluns or UNUNs but can be counterproductive with
>> large
>> turns ratio ununs. I have bought a lot of stuff from Balun Designs.
>> Their
>> 1:1 through 9:1 baluns are great construction  and performance with the
>> PTFE
>> tubing. At one time they sold a 49:1 UNUN and stopped selling it, except
>> by
>> special request.  I have two of them, with the PTFE tubing, and VSWR
>> performance at the high end is not very good.   My homebrew UNUNs, which
>> do
>> not use teflon tubes, have better performance at the high end.
>>
>> -Steve K1RF
>>
>> -----Original Message-----
>> From: Ilan Grosman
>> Sent: Monday, December 02, 2019 3:11 PM
>> To: ctsara at mailman.qth.net
>> Subject: [CTSARA] PTFE tubing for copper wire used for 49:1 balun
>>
>> Hi All!
>>
>> Any good (cheap) sources you can recommend for getting PTFE tubes to use
>> as
>> copper wire sleeves? Building a 49:1 transformer and want to replicate
>> balun designs approach.
>>
>> Thank you, and see you on Dec 5th.
>>
>> Ilan
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