Mark,
The most usual cause of a Q7/Q8 short to ground is that the thermal
insulators are not installed properly.
However, your statement that you see the same with the heatsink off
indicates that the Q7 or Q8 transistors have been damaged by a collector
to emitter short. If the K2 was subjected to a transmit without the
heatsink installed, that could be reason for the demise of Q7/Q8
transistors.
Make certain that the PA mounting hardware is installed correctly,
especially the shoulder washers.
73,
Don W3FPR
On 1/4/2020 9:11 PM, Mark Yergin wrote:
I'm in the final stages of my K2 build, but having a problem with Q7 and Q8
shorting to ground. When I did my Resistance Checks on pg 74, I had 3.66K
ohms to ground at the Q7 collector. So that was fine. But when I put all
the boards and panels on, then attached Q7 and Q8 to the heat sink, I see
about 135 ohms between the Q7 and Q8 collectors and ground. I assume
that's unacceptable. I see the same with the heat sink off. Suggestions?
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