RF Level Equations?

[N8YX]

On which frequencies are you transmitting when you see the overload occur?

[KD8TUT]

On which frequencies are you transmitting when you see the overload occur?

Pretty much all of them lol.

I tested the return wattage from the secondary receive antenna (over 10 watts when amp is at 500 watts) and then checked my work with an EE in my local ARC..

Based on the proximities involved I may need to isolate that antenna to ground during transmit.

My initial reaction was to do some math but my friend Earl (N8SS) informed me that the measurement I did was better since the math would only be accurate in a controlled environment- these antennas are in a forest so the results may or may not be accurate.

As a side note- this is when I'm thankful for our wide coverage repeater which allowed me to talk over the problem with Earl for an hour as I returned from a client site.

Bottom line is that if I want to use adaptive predistortion on transmit, with phase cancellation on receive, there is no choice but to use ppt---->relay---->antenna---->ground. Unless I want to modify the radio internally or buy a revised PA.

There may also be another issue- common mode on the secondary receive coax. I have a good line isolator to test that. So I'll eliminate that and then head to the ham store for a relay and a few doo dads.

It's possible I may buy a revised PA, or purchase the board and build it myself. But in the short term if grounding the antennas resolves the problem I'm good with it.