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Re: [TowerTalk] Balun Overheating?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Balun Overheating?
From: "Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>
Date: Mon, 21 Apr 2014 04:01:23 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 4/21/2014 1:59 AM, Grant Saviers wrote:
I melted the commercial "HD QRO" bead type choke off my GOTA G5RV feedline junction and since then only use the FT-240-31 cores stacked 3 or 4 at QRO with TFE coax (RG142 double silver) turns or the "big clamps ons" type 31 at up to 500w with RG8X, very convenient. Why use beads when inductance is proportional to turns squared? A much better use of ferrite is a larger core with the appropriate turns per K9YC or G3TXQ's data.

Never again G5RV's, fan dipoles rule!

This is what I use on 75.
http://www.rogerhalstead.com/ham_files/AntennaFeed2.htm

73

Roger (K8RI)


Grant KZ1W


On 4/20/2014 9:24 PM, Roger (K8RI) on TT wrote:
On 4/20/2014 10:26 PM, Jim Lux wrote:
On 4/20/14, 6:34 PM, Tom Hellem wrote:
Fellow TTers:

I built a balun for my triband yagi consisting of 50 type 73 ferrite beads
slipped over a piece of RG 303
coax, enclosed inside of a piece of 1-1/2" pvc. Had one of the wires break
inside and I surmised it must have
been a result of wind-caused vibration, etc. So after I repaired the broken
connection, I squirted some of that
canned foam insulation (the kind that is sold for foaming around windows &
doors, etc.)into the pvc enclosure,
encasing the entire piece of coax & ferrite beads in the stuff thereby
preventing any vibration , etc in the future.
Upon further thought I am wondering now did I invite the balun to overheat,
especially while running high power,
as any heat generated has no way to escape.
Does anyone have an opinion one way or 'tother?





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