Pete's warning is valid. I've charcoled wood with my 450 ohm, though I was
running 100w. Lesson learned. Always use plexiglass of plastic (or your HV
feedthrough idea). If you still want to use wood for the whole pain, then
cut out a square 3" by 3" and cover it with a 4" by 4" piece of plexiglass.
Another novel idea which does work (providing your window has just a single
layer of glass) is to use a capacitive feed through the closed window. I
ran this when I was a kid in Oklahoma. I cut 4 pieces of aluminum foil,
each 1 sq. ft. and pasted 2 of them to each side of the window, creating 2
big capacitors. I then carefully attached the feedline to the alu-plates on
each side of the window and it worked just as well (subjectively) as when
feeding directly through the open window to the matchbox. The only problem
I had was that the aluminum foil occasionally ripped and had to be replaced.
73
Rick
-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com]On Behalf Of ac5e@comcast.net
Sent: Wednesday, April 14, 2004 12:36 PM
To: larrylg1@roamer.net; tentec@contesting.com
Subject: Re: [TenTec] 450 OHM LADDER LINE FEED THROUGH FOR LOW
POWEROPERATION.
Well, the last time I was around the Matagordo country the mosquitoes were
about big enough to fly away with small children. And according to rumor did
fly away with a couple of wash pots. So I do understand you want to keep
them out of your house. Especially since West Nile Virus has become common.
But really, HV insulators are overkill unless you are running some serously
high power. We used to drill two holes an appropriate distance apart in a
piece of plexiglass (lucite) and replace a window pane, solder a lug to each
wire of the outside run of ladder line, run #8 screws through the lugs and
through the plexiglass. A nut on the inside secured that part. Two more lugs
on the inside run of ladder line and a couple of more nuts finished the
feedthrough.
Plastic would be better since it does not absorb water - and in window pane
sizes it should be cheaper - but if you must use plywood a few coats of
Varathane or a similar varnish should keep the wood dry.
73 Pete Allen AC5E
Never squat with your spurs on!
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