[TVARC] Recall of Request for Suggestions!!!

[Frank M]

Problem found and it was a very unique one.
I will try to simplify the issue and the solution.

The issue appears to have been caused by RF Leakage from Power Amp (500W) getting into the Icom IC-7300. The leakage occurred while operating RTTY.
Apparently, the leakage caused a setup modification in the rig related to the USB audio input when in Data Mode. Interesting that the bad setup does not reset when you power down. As with most rigs, when you power up, you always return to the same condition as when you powered down!!!
The Icom 7300 has a set up for choosing source of modulation when in Data Mode and when not in Data Mode. In Data Mode, the source in my rig was the USB input. However, that set up selection, although showing USB, was actually disabled so no modulation source was being used. Upon switching to the mic as the modulation source, and then back to USB, it caused that set up to reset correctly and now it uses the USB as the source for modulation in Data Mode.
Just one final note for any Icom 7300 users - upon inspecting the set up for modulation source in Data Mode, the display still showed USB but is was grayed out - not bright.  A very weird condition.
I am attributing this to the RF interference from the power amplifier when transmitting RTTY. I can not prove it, and I am not going to try and  prove it (who knows what it would do a second time).
This is my short version of the last 3 hours!!!
Something for me to put in my ham book of things to remember that I know I will forget.

Putting off contesting until tomorrow - need a break!!!

Frank KA1AF