At 7/31/2008 10:38, you wrote: > > If you've got the patience... drop the transmitter down to > > the exciter only power and see if you can reproduce the > > problem at any time. > > > > Do you have a circulator on the power amplifier's output? > >I have taken the amplifier out of line and had the same results. I've >also taken the duplexer out completely, and run the RX on the top >antenna, and TX on the bottom. I thought for a while that this solved >the problem, but it ended coming back eventually. There was quite a >bit of desense in this configuration obviously, so the feedback >probably just wasn't strong enough to overcome it, for a while.
I was thinking that this configuration might help, as I've seen moving to separate TX & RX antennas solve other 3rd party mix problems. The key is to separate the TX & RX near fields as much as possible so that any 3rd party mix will be more decoupled from your TX or RX antenna. Before you give up on this, try removing the duplexer T & feed the TX & RX legs of the duplexer straight to your 2 antennas. Separating them vertically as much as possible just might solve the problem. >I don't have a circulator in line. Would be a good idea to have, but I don't think it would help in this case - no other in-band signals to isolate. Bob NO6B
