Well done, Alan!
This is what I like: clever use of equipment that happens to be
available.
73, Dick, PA0SE
At 01:07 28-2-03 +0000, you wrote:
Hi all, I thought this little
episode might prove interesting and it
certainly finds a use for the "below 50MHz" part of a hand-held
scanner. I
have an AOR 2700 which purports to operate down to 100kHz, but like a lot
of
this kind of kit is very deaf down there. I did think it might be useful
for
DFing TV interfence, but it is too deaf even for that, without a
pre-amp.
I restrung my 60m-top Marconi last weekend and was disappointed to see
that
the tunning when paralleled with my 30m top inv-L was not at the
original
position. As it is a receive aerial is is strung with 1mm PVC coated
wire. A
quick measurement of the tuning inductor indicated only 80pF more
capacity,
which I guessed would mean a break inside the insulation about 16m from
the
feed point (5pF / m). After a little thought and a couple of coffees,
I
plugged the end of the unloaded 60m wire into the 600ohm output of the
PS-12
(W&G SIG GEN) turned up full and with the interenal resistor set to
"0". I
then walked down the wire (now dropped to the ground again), running
the
wire at right-angles over the closed telescopic aerial on the AOR2700.
The
"S-meter" gave fullscale on AM, and about 15m down the wire it
dropped
significantly ( to "S3"). A quick waggle of the wire confirmed
two breaks at
that point. I was quite pleasantly surprised that point indicated by
the
scanner s-meter was with an inch of the break. After a quick soldering
job
and a tape-up the aerial tuning inductor was back to where it was
expected
to be.
I know its not rocket science but its nice when these little tricks
really
work. The feed voltage from the PS-12 was about 0.7V r.m.s. It also
proved
my contention that a wide coverage receiver is one of the most useful
bits
of test gear you can have (I might add "portable" to that as
well now!!)
Cheers de Alan G3NYK
[email protected]
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