[Elecraft] K2 Problem 12 Watts Out With Power Control Fully CCW

[Joseph Szczubelek]

The build for K2 ser # 5628 has been going well until
I got to the "Alignment and Test Part III"  40 meter
transmitter alignment section. 

Problem: 

With current set to 2.0 AMPS and the power control
fully CCW I measured 7 watts on an external wattmeter.
The internal wattmeter had NO indication. When I press
the "tune" control with the display set for voltage
and current I see 13.3 volts and 1.88 amps. The
current will start to slowly rise at .02 amps per
second and will reach 2.00 amps in about 10 seconds
and the "HI CURRENT" message will appear with 7 watts
output. 

If I set the power to .5 watts the current will start
out at 1.98 amps and the 2.00 amp threshold and "HI
CURRENT" message will appear much quicker - about 1
second. I still get 7 watts of output indicated on an
external wattmeter. 

Setting the current to 3.00 amps and the power control
fully CCW I get 12 watts out with 13.0 volts and the
current starting at 2.84 amps creeping up at .02 amps
per second. At around 10 seconds the HI CURRENT
message will appear when 3.0 amps has been reached. 

Setting the power to .5 watts will cause the same
thing to happen but HI CURRENT message appears quickly
with 12 watts output. 

Additional Info: 

The K2 has passed all checks up to this point. I am
using a Heathkit 50 ohm dummy load. Turning the power
control up or down gives the  indication of the
desired power but has no effect. L1 and L2 gives a
nice peak for 40 meters. They were very close if not
right on from the 40 meter receiver test.  Measuring
the resistance at the collectors of finals Q7 and Q8
shows 3.7K for both transistors. The power output is
being controlled by limiting the current not by the
power control. The internal wattmeter gives no
indication on transmit but works as an S meter on
receive.  I am using a 30 amp Ashton switching supply.
It was Sunday evening so I called it a day. 


Best, 

Joe Szczubelek  -  K9DMV 



 
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