Quick and dirty ...

Steven London steven at ulysses.ACNS.ColoState.EDU
Fri Jul 31 10:17:26 EDT 1992

For those of you looking for a low budget approach to interstation
interference for a multi-single or multi-2, here's what I do :

For each station,
I have built a simple wavetrap, consisting of a series circuit
of a variable capacitor and an inductor.  This wavetrap sits between
the rig and the amplifier, across the coax line (between center conductor
and ground).  The wavetrap capacitor is tweaked for the band that the
OTHER station is operating.  It serves two purposes:  it reduces the
overload caused by the other transmitter, and it reduces the phase noise
generated by the transmitter that interferes with the other station.

I find that careful tweaking gives me about 40 to 50 dB attenuation.

The situation here is almost as bad as K5OJI - 2 towers 70 feet apart,
about the same height.   Before I built the wavetraps, the phase noise
generated by my TS-940 when it was key-up (in the xmit position) on 10
meters, was S9+10 dB on the 15 meter receiver.  You can imagine how
many volts of RF was being pumped into the 15 meter receiver when I
had a KW output on 10 meters.

I know, this is a crude solution to the problem, but this is a low-budget
operation !

Steve, N2IC/0   

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