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Re: K2 PLL Oscillator Range Test failure (barely)

Posted by Don Wilhelm-3 on Jan 03, 2005; 5:50pm
URL: http://elecraft.85.s1.nabble.com/K2-PLL-Oscillator-Range-Test-failure-barely-tp373202p373204.html

Scott,

Just to check, can you look at what the voltage swing is at U6 pins 1, 2 and
3 when you do the Ref High Freq and Ref Low Freq measurements? Compare to
the voltage table on page 17 of Appendix E in the manual.

If the voltage swings are not correct, you have a likely problem with the
PLL thermistor board, but if the voltage swings are correct, you should look
for the problem in the area of the PLL crystal and varactor diodes.  First
check the soldering carefully, and check all components shown in the
scheatic  associated with the PLL Reference oscillator area (upper left
corner of RF board sheet 1 of 4).

If you find all is OK soldering and component wise, it may just be that your
crystal is not being pulled far enough.  The cure for that is to change L31
to 12 uH instead of the 10 uH that is currently being shipped with the K2
kits.  An e-mail to [hidden email] should start a new inductor on its
way to you.  I believe Elecraft is still providing this replacement on an
'as needed' basis, free of charge.

73,
Don W3FPR

----- Original Message -----

> On page 60 of the K2 manual the PLL Reference Oscillator Range Test
> asks for the Ref. High Freq. and Ref. Low Freq. measurements. I have
>
> HI = 12099.67
> LO = 12090.50
> DIFF 9.17
>
> which is less than the 9.8 to 15 kHz required by the manual.
> Everything else looks good. Any ideas? Any help would be
> appreciated. Thanks.
>


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