I recently put up an inverted vee for 80 and 40, hung off the top of my
LM-470E 70' crank-up tower. I noticed that when I went to listen on it, I had
a horrendous 20 dB over 9 noise level that was not there on my other, lower
40m antenna.
I tried putting in 10 dB attenuation on the TS940 and the problem went away!
This antenna has proven to be a good performer, as long as I put in 10 dB
attenuation on the 940. This holds true for 80m as well as listening on 20 and
15.
The other antenna, which does not exhibit these problems, is a Hygain Explorer
14 with a 40m kit mounted on a tripod on the roof at about 25 feet. (BTW, the
inverted vee whips the shortened 40m rotatable dipole by as much as 2 S-units,
as expected).
I know that there is a strong AM broadcast station about 2-3 miles from me,
which has interfered with the telephones, but I haven't had any trouble from
it in a couple years.
I am assuming that I am experiencing an overload situation, which must be
pretty severe, since when I add the attenuation, the S-meter falls from 20 dB
over 9 to a more normal noise level of S-2 or 3. The overloading signal must
be really driving some receiver circuit "crazy" to generate that much
noise/distortion.
I am interested in any opinions on what is going on here. Is my 940 broken
(bandpass filters not working, other circuit problems)? I am considering
adding a high-pass BCI filter to see if that helps. Any recommendations on
filters?
If this is not the right place to discuss this, sorry. Thanks for any ideas.
73,
Mike K7NT
K7NT@aol.com or MConatore@yahoo.com
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