Steve: Without some test equipment, it will be hard to see exactly what is
going on, but your suspicions are likely correct. Some sort of filter on
the 6 meter station is called for. When I had a similar issue (not doing
EME) I put one of the $40 Diplexers on the 6 meter station (HF/2 meter
diplexer) and interference went away. Its also possible some of the noise
is being generated in the Wattmeters. Easy test -- take them out of line
and see what happens.--Mike, WV2ZOW
On Wed, Jul 29, 2015 at 12:34 PM, Steve Kavanagh <sjkavanagh1@yahoo.ca>
wrote:
> Here's a question for some of you more experienced multi-ops. At our
> recent CQ WW VHF Contest operation in FN05 we had some interference from
> the 6m transmitter into the 2m receiver. It wasn't totally prohibitive but
> it was annoying at times...we had to stop transmitting on 6m while
> attempting EME contacts on 2m, for example. The setup and tear-down were
> done in a great hurry this year, so we had no time to investigate
> properly. I'd like your suggestions as to the most likely route by which
> the interference was getting in and how to fix it.
>
> The 2m station was as follows: Elecraft K2 - DEMI transverter - DCI
> bandpass filter - TE1452G amp - Bird43 - antenna.
> The 6m station was as follows: Kenwood TS-2000 - TE0552G amp - Bird 4304 -
> antenna.
>
> The two antennas were around 30 ft apart and at the same height.
>
> My first guess is that there is some transmitted noise at 144 MHz from the
> 6m rig/amp which got into the 2m antenna. That could be eliminated by a
> low pass filter or stub on the 6m output. Are there other possibilities I
> should consider before we try this again? The 6m amp was run from a
> switching power supply, which makes me wonder a bit. Radiation from the 6m
> amp power cables or ingress into the 2m station somewhere after the DCI
> filter (or on power lines) might be other possibilities.
>
> What do you think?
>
> 73,
> Steve VE3SMA
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