[Kenwood] TM-2550 PLL problem

[Steve Garwood]

I'm having a problem with a TM-2550A - a PLL problem.

When the PLL is unlocked, what checks can be done to locate the source of
the problem?  The 10.24 Mhz oscillator is running, as is the 39.480 Mhz
oscillator.  It appears that the mix signal provided through IC-2 is being
shut down by the unlock switches....  The test point associated with the RX
VCO set reads .02 vdc.  Adjustments have no effect.  It appears that the VCO
is being shut down by Q14 being biased on.

Is there some way to defeat the "unlock" voltage for testing to narrow down
the search, and lastly, are there any common problems that crop up on this
series of radios?

Thanks for any advice?

Steve
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Steve Garwood, N�CZV / USAF MARS  AFA1GQ
Attica, Ohio
n0czv@willard-oh.com


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