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

[Steve Dick]

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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