[TenTec] QRO Creep

[Max Moon]

Hi Folks,

You might think the subject is some jerk who keeps parking his KW on top of
my QRP signal. But what I'm really interested in is why my 5 watts of CW
slowly grows to 6 or 7 or 8 or more while I operate.

I use a Corsair 1 for QRP & have an OHR WM-2 to check my output. After
adjusting the ATU I adjust the drive for a bit below 5W. However, while I
operate, the output creeps up steadily. This is with the ATU/SWR meter
showing no change. If I don't check the output periodically, it can actually
go beyond 10W.

This happens only during the first 40 minutes or hour that the Corsair is
"turned on." Then it stabilizes and output remains wherever I set it, even
at QRPp levels.

I figure this is part of an extended "warming up" but I don't understand WHY
it happens. For example, why doesn't output *decrease* while operating? Or,
why doesn't one warming up change counter-balance another change so output
remains constant although, say, some component values change one way or
another.

I'd be grateful for somebody's explanation of what is actually happening in
there, what interactions occur.

Thanks!

Max, k0max