Hello Dave,
This sounds like a dirty potentiometer for the drive control. It is a 25k
potentiometer.
If possible, try to clean it with a spray.
It is definitely NOT the T/R relay because the 509 does not have a T/R
relay.
The older 505 had a reed relay mounted on its Control Board, which switched
the antenna back and forth between the receiver and the transmitter.
The 509 has a tap going to the antenna and it is switched in and out, also
on the Control Board, using transistor M8 and diode D3. I doubt that this
problem is on the Control Board.
73 - Rick, DJ0IP
(Nr. Frankfurt, Germany)
May the Sunspots be with Us!
-----Original Message-----
From: TenTec <tentec-bounces+rick=dj0ip.de@contesting.com> On Behalf Of
wb0gaz via TenTec
Sent: 21 August 2021 04:30
To: tentec@contesting.com
Cc: wb0gaz@yahoo.com
Subject: [TenTec] Argonaut 509 - odd behavior with Drive control vs max
output power
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 <mailto:wb0gaz@yahoo.com> wb0gaz@yahoo.com
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