Re: 8642B displays A6A1 transient failure F3 when audio peaks at FM mod input
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Jim is correct. Switching from AC coupled FM to DC coupled FM causes the FM PLL to unlock and incur a frequency error. This error is mitigated summing a DC voltage onto the FM VCO tune line. The counter is used to determine the unlocked frequency error which is then used to set the value of the compensating DC voltage. ? Brian (designer of the 8642 FM PLL) ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jim Summers
Sent: Monday, November 05, 2018 8:29 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] 8642B displays A6A1 transient failure F3 when audio peaks at FM mod input? Guessing here, but switching to ext DC may cause execution of a routine to calibrate the free running frequency of the FM VCO. ?If you switch back to internal before the routine is complete it might flag an error. I have a update
I found when I turn on FM modulation and alternate from internal to external DC I get A6 counter fault, before it seemed somewhat obscure if the A6 module was actually working, I think I determined now it isn¡¯t though it seems like a partial failure
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