Hello all.
I have been working on K2/100 #4684.
It worked beautifully in a QSO with my brother on 40m last weekend until
the power out went to 0.
Doing some troubleshooting with the procedures in the manual this is
what I came up with.
I started with the receiver and those measurements were within reason.
I moved on to Transmitter Basic Voltage checks and recorded these voltages.
These are all on the basic K2 with the SSB adapter removed and jumpers
for J9 and 10 and C167 installed.
D6 Anode on tx - *.25V*
D7 Anode on tx - *7.9V*
Actual Power Output - *0.3W*
I moved on to the ALC voltage checks.
Power Control Test - *4.97V *Not even close.
------------------------------------------------------------
Transmit Mixer, Buffer, Band-Pass Filter, T-R Switch
*
*Xmit Mixer Output - *.212 Vrms*
Buffer Output - *1.9 Vrms*
Band-Pass Filter Output - *0.056 Vrms
*T-R Switch #1 Output - *0.057 Vrms*
All way too high.
----------------------------------------------------------------------
Pre-Driver, Driver, PA.
Pre-Driver Output - *0.170 Vrms*
Driver Input - *0.024 Vrms*
Driver Output - *4.07 Vrms*
PA Input - Q7 - *.94 Vrms
*Q8 - *1.08 Vrms
*RF Detector Input - *0.0 Vrms * Not good at all! I checked D9 and it
is a 1N5711 and it is installed correctly.
------------------------------------------------------------------------------------
PA Transistor Tests. Both flunk with very low resistances.
DMM positive lead on Bases I get about *.65 Ohms* to the collector and
emitter.
DMM negative lead on Bases I get about *1.7 Ohms *to collector and emitter.
I checked the hardware and thermal pads for both Q7 and Q8 and they're
all in great shape. No mis-alignments of shoulder washers or thermal
pads. No torn thermal pads etc.....
Which component or components are bad.? I suspect I'm going to be buying
new finals possibly a driver and 1N5711 diode. The voltages are all
haywire after the pre-driver Q5.
Thanks for your help.
--
R. Kevin Stover ACØH
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