[TowerTalk] Balun for G5RV

[Jim Thomson]

Date: Tue, 01 Feb 2011 21:43:11 +0000
From: Steve Hunt <steve at karinya.net>
Subject: Re: [TowerTalk] Balun for G5RV
To: towertalk at contesting.com
Cc: towertalk at contesting.com
Message-ID: <4D487E6F.8010706 at karinya.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Be aware that if you're tempted to use the G5RV on a band where the 
VSWR(50) is high, the 1:1 balun windings may need to withstand some 
quite high voltages. For example, on 30m at 1400W the voltage between 
the wires of the bifilar pair will be about 2,500V peak.

Steve G3TXQ

On 01/02/2011 21:19, Rick Karlquist wrote:
>   I meant to say "low voltage lighting" zip cord.  It has very
> thick insulation.  Although meant to operate at 12V, it should
> be good for many 100's of volts.

### 10-16 ga solid enameled magnet wire... with polyimide insulation is good
for 15 kv.  My understanding is polyimide and kapton are one and the same. 
You can buy magnet wire  from planet wire and other sources..in a variety
of different insulation types..like nyclad, formvar, etc.  You can also get polyimide 
magnet wire  as big as 6 ga.  Manfred tells me he can obtain it in 4 ga in Chile.

## If 15 kv magnet wire isn't enough for you, then slide some teflon  spagetti
tubing over the magnet wire 1st.   Alpha wire and other's have teflon tubing, in any size,
designed to slide over any ga wire.  That will increase it to at least 25 kv.  That's  50 kv
between adjacent turns.Teflon tubing slid over flex weave also works well.  It's the exposed 
splices etc, that you have to worry about..and also arcing from turns to the ferrite core. The cores
should really be wrapped with polyimide tape as well. 

##  The above  procedure is used, when using YC-156  power levels.  The Palstar + Amidon 1:1 and
4:1 baluns cracked, burnt, and arced badly at the exposed splices.  The Palstar was rated for 5 kw
and the Amidon was rated for 10 kw.    The only commercial 4:1 balun that has survived is the Array
Solutions types.

Jim  VE7RF