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

[Ilan Grosman]

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
> ________________________________________________
> CTSARA mailing list
> Home: http://mailman.qth.net/mailman/listinfo/ctsara
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:CTSARA at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> All posts must be sent in Plain Text, no HTML. Links will Function. No
> attachments are allowed.
>
> Unsubscribe from CTSARA: http://mailman.qth.net/mailman/listinfo/ctsara
>
> Analog Repeaters:
> "S": 146.655MHz -600KHz PL 114.8 Hz
> "H": 146.655MHz -600KHz PL 100 Hz
>
> DMR: 447.125 Out 442.125, Color Code 2
> (Listen here)
> https://www.broadcastify.com/listen/feed/21651
>
>