[TowerTalk] station to station interference

[Rudy Bakalov]

Some fresh observations from CQ WW RTTY.

At VC3S we entered M/S HP, using two radios with two amps, each amp running under 1500W.

Our antennas were a tribander for 20 thru 10, a yagi for 40, inv.-V for 80, and an OCF for 40 thru 10.  All antennas were on the same 95' tower.

The tribander was fed using a VA6AM designed triplexer and HP filters. Since the triplexer is rated for 3 kw we kept each amp at under 1500W.

Each radio also had automatic bandpass filters from Array Solutions/Hamation. The goal of these filters was to 1) filter out any residual RFI that leaks in thru the SO2R antenna switch or other means and 2) clean up the radio output so that the amp does not amplify any RFI.

The end result was absolutely no interference between the two radios. Note that one of the radios was an Icom 7300 which would illuminate the overload indicator if there is ADC overload (even if we humans think the radio is not overloaded); we never saw the indicator illuminated.

Conclusion- filters are very effective in dealing with heavy RFI, including the extreme situation where two radios share the same antenna at the same time.

Rudy N2WQ