[TenTec] Argonaut 509 - odd behavior with Drive control vs max output power

[wb0gaz at yahoo.com]

 My Ten-Tec Argonaut 509 (I'm not original owner; I've had it for a long time but only put it back in service earlier this year) normally puts out about 2W PEP/CW when powered by 13.8VDC.

I was using it this afternoon to test a semi-homebrew solid state PA and discovered that in the LOCK setting, if I rapidly move the DRIVE control clockwise to max, output power comes up to about 4W (at least on 40M where I'm testing currently). If I leave the DRIVE control at max, then move out of LOCK then back into LOCK (while keeping DRIVE control at max), output is at 2W when it goes back into LOCK. 

Some other tests - sending CW doesn't exceed 2W regardless of how I move the DRIVE control while sending.

If I put the keyer into TUNE mode (steady carrier), behavior is same as if putting the radio into LOCK mode.

If I put the keyer into TUNE mode, then (in either CW or LOCK mode) adjust DRIVE fully clockwise for the higher power level, then quickly flip between CW and LOCK (back and forth), output stays around 4W, however, if I leave a fraction of a second in the intervening SSB (no output) mode, power goes back to 2W.

Puzzling over this and the only thing I can think of is maybe the T/R reed relay's contacts are dirty?

I don't think there's ALC in the 509, true?

Any other suggestions/ideas?

Thanks,

73 Dave WB0GAZ wb0gaz at yahoo.com