Hi, all.

I think I have finally gotten to the bottom of my RFI problem on 20 meters 
when using the Alpha Delta DXCC antenna.

Now, all I have to do is figure out how to fix it, and how to replace what 
little hair I still have that has been pulled out in the process.

My problem is with the cable for my Heil Gold Line mic!  Thanks to Kevin 
(K7RX) for giving me the clue.

I used headphones to monitor my transmit audio, first with the stock mic 
that came with the TS480.  Crystal clear audio on both 100 watts, and 600 
watts using the amp.  Then, switched back to the Heil.  Crystal clear audio 
on 100 watts, but terribly distorted audio using 600 watts and the amp. 
Tried putting an RF choke around the Heil mic cable, which reduced the 
RF-generated audio distortion considerably but not completely.

Just for grins, I tried the Heil set-up on 40 meters with both low and high 
power, and had crystal clear audio both times.

So, obviously, that mic cable is doing something to me on 20 meters.

Will write to the folks at Heil for their suggestions, and would appreciate 
any thoughts any of you have as well.

I'm relieved, but now have to figure out what to do to correct the 
situation, if I'm going to use my Heil gold line mic on 20 meters with the 
Alpha Delta DXCC.

73 from Tom Behler: KB8TYJ