Date: Tue, 1 Jun 2010 15:18:59 +0200
From: "DF3KV" <df3kv@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
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