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Old April 24th 12, 11:08 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Jul 2006
Posts: 220
Default Indoor Counterpoise For Random Wire Antenna

I am using a random wire antenna which runs outdoors through a hole in a
window frame.

I do not have access to any good RF grounding system and plan to use an
indoor
counterpoise wire from the ground connection on the tuner (MFJ-949E). I have
a
nice role of #18 wire, the end is connected to the tuner, and it is my
intention to
unroll it along the floor through my suite until such time as it is properly
tuned.

MY QUESTION IS - How can I tell when I have unrolled the right amount of
wire
for the frequency in use. I know it will not be 1/4 wave, and that it
should be less.
From what I understand, when it is adjusted properly I should not have any
hot
RF burning my lips from the mike. Checking it with my lips is not what I
call
a desireable means of testing, and being single I cannot call my wife to
test it
for me. I'd like to find a better way and hence my questions.

I believe (according to what theory I have learned) that the tuner chassis
would
be hot with RF, with the amount of RF becoming less and less as the
counterpoise
wire approaches the proper length. If this is true would a simple RF sniffer
tell me?
I can rig one up fairly easily.

OR - What would I be looking for using my MFJ-259B SWR Analyzer? I expect
what it would show readings similar to a dipole with resonance at the
operating
frequency and an impedance (resistive) of somewhere in the order of 60 ohms.
plus or minus -- is this a correct assumption?

OR -- does anyone on the group have any suggestions that will tell me when
the
system is properly adjusted -- the simpler the better!

Once I have found how to do this, I can put tape markings on the roll of
counterpoise wire to show the appropriate length for each band or narrow
band of frequencies in which I will be operating.

I have already tested the hole -- it is just a little less than 1/4 inch
diamater,
but that seems to be enough to let both sidebands through -- I carefully
tested
that using AM which proves that two sidebands can fit through the hole at
the
same time, which allows me to further assume that either the upper or lower
sidebands should squeeze through easily! :-)

Thanks in advance for any assistance you can provide in this matter.

Irv VE6BP

On the air finally but afraid to get to close to the mike! I may have
to use rubber gloves and teflon lip gloss!




 
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