[TenTec] Argo V Distortion

[Reed]

I have had several reports from time to time of my audio sounding distorted.  Some say it sounds like RF getting into rig.  I have listened to my audio on another rig & I can't detect any unless I turn the mic gain up too far. Using outside antenna or dummy load. I believe this is happening on voice peaks. One ham had me turn mic gain all way down to 7 o'clock. No ALC light at all was blinking. Distortion went away, but so did most of the output power.  I run gain at 8 o'clock just were the ALC light begins to blink. Power set to full.

I can switch to another rig & distortion is gone.  Other rig using same power supply, coax, antenna, ect. as Argo 5.

Mic I use is hand mic or Heil inside an old MC-50 mic stand. Use Heil with other rigs & no distortion.

Use Argo 5 mostly on CW, but would like to use it on phone without wondering if I'm distorted.

Has anyone else experienced this problem?

Oh, I don't use a ground.  I wouldn't think this would be a problem since none of my other rigs are grounded & they don't have this problem.  Sitting on a rock with 17 inches top soil. All my antennas are coax fed Belden RG-213. Antenna is Hy-Gain 2 element beam & Windom about 75 feet from shack.  Power supply is Astron 35 & have used other power supplies with same result. Use mostly 20 meters, but have had same report on 17 meters. This has happened once portable.  No problem on CW or Digital. Have a dedicated electrical 20 amp circuit to equipment.

Any help would be appreciated.

Thanks,
Reed  W4JZ