[Mobile-Portable] Iron Horse 40m Ground?

[Jay Eimer]

I have no idea how old this spring might be.  Bill is 80+ years old and has
been a ham for over 50.  When he got this antenna, he said he needed a
spring for it, and I scrounged in his garage and found that one on the work
bench.  It's galvanized (not chromed like the ones I see at truck stops and
Radio Shack), so I'm betting it's been around a while.  It's also obviously
been used (on another vehicle) at some point in the past.

I think I'll just pick up a new spring and swap them out.

I saw the note about the stinger in the tuning instructions.  Shouldn't be a
problem.  We tried without the spring and even where he wants it tuned
(7290KHz) it's still only about 4-1/2" below the ferrule.  The coil doesn't
start until about 6" down.  But I'll keep an eye on it when we get it
"really tuned".

Thanks,
Jay

-----Original Message-----
From: mobile-portable-bounces at mailman.qth.net
[mailto:mobile-portable-bounces at mailman.qth.net]On Behalf Of Tom Bates
Sent: Sunday, July 18, 2004 23:34
To: Mobile-Portable Reflector
Subject: Re: [Mobile-Portable] Iron Horse 40m Ground?


>>So I got out the antenna analyzer, and the needle was swinging all over
everywhere - seemed to be when the antenna was moving

Jay...  Sounds like the first thing to investigate would be the spring.  You
said "old", so mebbe corrosion or rust.  A quick test would be to make a
wire jumper with ring eye terminals to fit 3/8 studs on each end.  One end
under the spring, and the other on top of the spring.  These springs are
notorious for generating noise in the cheepie ones.  The better grade
springs have a wire braid going from end to end inside the spring.  Another
possibility is that the loading coil is just too close to the body of the
jeep.  Try swinging the bar farther away from the body to see if it has an
effect.

Another thing to watch with the iron horse is the length of the stinger
INSIDE the tube.  If you have to keep shortening it to tune it, make sure
the stinger inside the tube doesn't go down so far that it's actually under
the loading coil turns.  If for some reason you need it that short, it would
be better to cut off some of the stinger.

73,   Tom   AA1NZ
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