Don,
The safe thing to do is replace Q11 and Q13 in addition to Q7 and Q8.
Sometimes Q11 and Q13 fail as a secondary failure when the PA
transistors fail.
On the part where you say there is only 7 watts out while the K2 shows
15 watts, I am going to make a lot of "IF" statements - read carefully
for the conditions.
IF you have only the base K2 (no KAT2, no KPA100) - you must have a 50
ohm non-reactive load to have valid power readings on the K2 display.
Connect a good 50 ohm load and you wattmeter to check. If the K2 power
display does not track, check the soldering around the resistors
associated with D9 - occasionally, D9 may fail, but that is not a
frequent occurrence.
OTOH, if you have the KAT2, KPA100 or KAT100 installed, those each have
wattmeters - the wattmeters need to be balanced and calibrated (see the
manual for the particular option). Check the 2 diodes (2N5711s)
associated with the wattmeter and replace if they are questionable
before attempting to balance and calibrate the wattmeter. If you cannot
achieve a good null when balancing the wattmeter AND the wattmeter has
worked correctly before, damaged diodes are the most likely cause. If
it has never worked right, there is a problem with the bifilar wound
transformer or soldering.
I would give you more specific information, but I am on vacation this
week and do not have all the manuals with me.
73,
Don W3FPR
On 12/15/2011 12:41 PM, NK6A-Don Minkoff wrote:
> The K2PAKIT comes complete with additional replacement bias transistors,
> Q11 and Q13. Although the K2 does operate up to 7W out (while showing
> 15W) , there is no adjustment in a linear fashion with the power knob.
> 2W out when showing 5W on the display. Should I replace automatically
> the bias transistors along with Q7 and Q8? That was my plan. Just
> wanted to check with any experts out there.
> Thanks,
>
> Don, NK6A
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