[DSP-10] Intermittent PLL Lock Issue

[Richard Miller]

Hi Jimmy: At this time I am using the internal 10MHz XTAL. After review, and running UDIAG2.EXE, I am beginning to worry something may be wrong with the DSP board. UDIAG does not cycle through and bring the appropriate lines to HIGH as outlined by the troubleshooting guide. In my case, all the lines come up high and remain there.  73
Rich
      From: Jimmy Oldaker W7CQ <W7CQ at teleport.com>
 To: av8torrich at yahoo.com 
 Sent: Sunday, November 29, 2015 11:58 PM
 Subject: [DSP-10] Intermittent PLL Lock Issue
   
Rich

you wrote:
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All: I seem to be having a problem with the PLL. I am ableto lock the PLL sometimes, and it will remain locked for a hour or two.Then for no real reason, the PLL will become unlocked. I am able tosometimes get it to relock by adjusting L102 for 127.335MHz when at147MHz. This is not repeatable, and it does not always lock once againwhen adjusting L102 for the correct frequency. Once I achieve PLLlock, it will once again run for a few hours, and then come out of lockagain.   Anyone ever seen this issue? If so, what were yourfindings? Rich, AJ3G 
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I had a similar problem years ago.  

First: Rre you using the internal 10 meg crystal or an external source?  My problem existed only with the external 10 meg sorce from my GSlocked Frequency standard and not the on board 10 meg crystal.

My problem turned out to be with with the signal from my external GPSlocked 10 meg source to the DSP10 input.  It was high enough at theGPS Frequency standard but not at the DSP-10. The Level was too low hadgotten lower some how.   Time to check the RG58.

An investigation showed that the BNC cable and / or connectors had gotten"lossy" and was old.   ( I was using some"old" leftover RG58 from unknown sources and it had over timedropped the signal to the DSP-10 right to the ragged edge of lock for thePLL. )    IThe cable was fine 5 years earlier so I put ina NEW and shorter piece of RG58 with NEW connectors and this raised thelevel up that the problem never has occurred again.

This may not be your problem but it fixed mine.

Good Luck

Jimmy W7CQ
 73's  -  Jimmy  -  W7CQ -  CN83jx

w7cq at teleport.com

homepage:  http://home.teleport.com/~oldaker/