[Elecraft] Transmit power control problem

[Pauli Nunez EA3BLQ]

Hello friends and greetings from Barcelona, Catalonia, Spain,

That's me again looking for help from you, the Elecrafter's community.

After having solved my recent "Info 80" trouble and since I had upgraded my
KPA100 and all the F/W, my K2's configuration got quite disarranged, I
decided to implement all the mods to upgrade my K2 rev A to a K2 rev B,
before getting into the configuring and aligning task (I had installed some
of the mods but not all) so I purchased the K2ATOBKT kit and did a lot of
disoldering and soldering. All has run as per the manual but (Why there's
always a but? Is it Murphy's Law?) now I have got a transmit power control
problem.

When I key down (TUNE) the K2 and independently of the value I set in the
POWER Control (be it 0.50, 2.00, 5.00 or 10.00 watts) I always get the "Hi
Cur" message and the internal wattmeter drops to 0.3 watts, but the truth is
that the power transmitted into a very well calibrated 50 Ohm Dummy Load and
RF Power Meter (the QRP RF-Power Meter PM-1300a by SSB-Electronics) always,
and I mean always with independence of the K2 POWER Control, reads between
10-14 watts depending of the frequency.

Have made the resistance checkings and they are OK

My PS is a switched Daiwa SS-330 X with an output voltage of 13.8 v fixed
and an output current continuous of 30 A
Measuring the voltage at the K2 Aux 12v connector I get the following
readings:

K2 switched OFF = 13.84 v
K2 switched ON  = 13.62 v
K2 transmitting   = 13.16 v

With the Cal Cur set at 2.5 A, on my DMM I get the following current
readings:

K2 receiving   = 0.29 A
K2 transmitting = 2.51 A

The DC voltage readings for the PA finals Q7 and Q8 are:

Collector K2 receiving     = 13.60 v
Collector K2 transmitting = 11.98 v
Base      K2 transmitting =   0.62 v

DC voltage for the PA driver Q6

Collector K2 receiving     = 13.60 v
Collector K2 transmitting = 12.60 v
Base      K2 transmitting =   1.02 v
Emitter   K2 transmitting =   0.26 v

I fear the PA finals may be damaged so they do not obey the
POWER control settings, but am not convinced of that and
although I have the K2PAKIT ready, I do not want to replace them
unless it is necessary.

BTW, the heat sink is isolated from the Q7 and Q8 collectors.

Any ideas and/or suggestions will be much welcome.

Sure I am missing something but honestly, at this moment, I do not
know what. Look forward to hearing from you. Thanks in advance.

Best 73

Pauli, EA3BLQ
K2/100 # 1044
ea3blq(at)menta.net
ea3blq(at)qsl.net
URL: www.qsl.net/ea3blq