[TowerTalk] Type 31 baluns

[Jim Thomson]

Date: Tue, 1 Jun 2010 15:18:59 +0200
From: "DF3KV" <df3kv at t-online.de>
Subject: Re: [TowerTalk] Type 31 baluns


Hi Jim,

Why should one bother for wire and core insulation if the balun will be used
to feed a 50 ohms load?

73
Peter 

##  Exactly my point.  The fellow was bent on using enameled wire.  I didn't know if it was
for a 1:1 choke balun... or 2:1  or 4:1 nor what freqs.  If enamel wire has to be used, or if 
silver plated flex weave is used.. it has to be insulated real good.  For a 1:1 balun... IMO...
it's not worth the hassle. 

## I agree, if it's  just for a 50 ohm choke balun.... just use teflon coax. like RG-393/400/303... and either
wrap it around type 43/31  cores... or  slide large diam type 43/31 beads over the coax,
and be done with it.

## BTW... I found an old, never used F-12  B-1/C  25 kw balun.  It's supposed to be good down to
80m band.   I measured the uh  from center conductor of the type N.. to opposite end.. and it's aprx
65 uh.  It's 17" long... an looks identical to a CAL-AV  EB-3..except the colour.  I'm sure it uses type 77
large beads slid over 393 coax.  Does anybody know when type 31 material 1st came out ?  I believe
type 31 has only been out since 2005.  My B-1/C is around 1998 era.   The EB-3's are the same 17" long
but are only aprx 38 uh. [and only good down to 40m... 960 ohms resistive]

## other than the semi useless type N... the B-1/C will not heat up either.  I don't think type 77 material
is optimum these days... except for maybe 160m. 

Later... Jim   VE7RF