[TowerTalk] W2AU Baluns??

Guy Olinger k2av at contesting.com
Fri Mar 17 14:53:59 EDT 2017

On Fri, Mar 17, 2017 at 1:01 PM, Jim Brown <jim at audiosystemsgroup.com> wrote:
> Why not make your own?  k9yc.com/RFI-Ham.pdf


Over a decade ago, following some RadioWorks failures at W0UCE(SK),
taking failed units apart, there actually was a very simple way of
rebuilding burned/melted coax wound on ferrite rod devices: Rewind
with RG400.

RG400: 50 ohms. Same outer diameter as RG58. Teflon jacket, teflon
dielectric, silvered copper double woven shield, multi-stranded
silvered copper center conductor. Highly flexible. Rated to 7 kW on
HF. Specifically designed for aircraft to endure fire without failure.
Specifically designed for aircraft to allow small radius bends found
in wiring harnesses.

When soldering on connectors, never need to worry about melting jacket
or dielectric. Heat it good and hot and let solder flow like water.
Uses the UG175 adapter for PL259 also used for RG58. Heat up the whole
dang thing until solder flows Jumpers made this way last forever.

RG400 not an obsolete product, still manufactured new and widely used
today. Odd lengths available on eBay attached to various connectors
where sellers are recovering some money from jumpers no longer needed

Extremely long shelf life, maybe 50-100 years, maybe 500 years?.
Teflon very gradually turns a little tan in color, and maybe a little
stiffer. If you wound it on a rod or core and put it up there it just
sits there and does its job.

Why on earth would someone put together a carefully designed device
and wind it with cheeeepie coax and then mount it out on a boom at the
top of a tower. Reeks of compulsive self-flagellation.

Everything I've ever made with RG400 and still have a use for is still working.

There is a degree of satisfaction in solving a station issue once and
for all and forgetting about it forever.

There is an RG8 size version of RG400: RG393. Quite a bit stiffer for
sure, but using a permanent balun device from RG400 and a stretch of
RG393 getting from an out-the-boom feedpoint to a manageable spot on
the mast will keep you from having to take that antenna down just to
replace cheeeeep coax.

73, Guy

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