K2 fails PLL Reference Oscillator range test

[Clark Ward]

Hi guys,
  I'm on page 60 and had been having a heck of a time getting the 4MHz
Oscillator calibration in spec.  Got it in spec (12110.84), and proceeded to
the PLL Reference Oscillator range test.  Pushing Band+ and Band- yielded a
change of a few Hz, but nothing approaching the required range of 9.8kHz -
15 kHz.   I have already checked every component going line by line through
the manual, all soldering has been checked about 10 or 20 times by this
point (in the process of getting the 4MHz oscillator into spec).  Q19 was
replaced, and X1 also.  At this point, I have to wonder if it's one of the
ICs in the PLL section.  This has been frustrating me for a couple of months
now.

Any help is greatly appreciated.

Thanks & 73 de Clark KI4GYT
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[John, KI6WX]

Does the DC voltage change at pin 1 of U6?  If yes, the problem is getting
the voltage to the varactors or with the varactors.  If no, the problem is
with the DC circuitry around U6 or U5.  Once you know the voltage for
Band+/Band-, the problem should be fairly easy to track.
-John
 KI6WX

> Hi guys,
>  I'm on page 60 and had been having a heck of a time getting the 4MHz
> Oscillator calibration in spec.  Got it in spec (12110.84), and proceeded
> to
> the PLL Reference Oscillator range test.  Pushing Band+ and Band- yielded
> a
> change of a few Hz, but nothing approaching the required range of 9.8kHz -
> 15 kHz.   I have already checked every component going line by line
> through
> the manual, all soldering has been checked about 10 or 20 times by this
> point (in the process of getting the 4MHz oscillator into spec).  Q19 was
> replaced, and X1 also.  At this point, I have to wonder if it's one of the
> ICs in the PLL section.  This has been frustrating me for a couple of
> months
> now.

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