[time-nuts] 5370A Trigger

[Bob Camp]

Hi

There is a very extensive calibration / alignment process for the 5370. It sounds
a lot like your box was set up “cold” rather than after a proper warmup. There is a 
lot of “stuff” in there, so picking out exactly which adjustment is drifting is going to 
be a guessing game. 

Bob

> On Oct 26, 2015, at 3:55 PM, Matthias Jelen <Matthias.Jelen at gmx.de> wrote:
> 
> Hello Time-Nuts,
> 
> once again a question to the 5370 experts:
> 
> After some time of operation (hours...) my 5370A starts to become noisy. This can be seen best when teeing the 10 MHz REF OUT to IN A nnd IN B, choosing TI and setting STD DEV, 1k samples. When everything works well, the displayed value is around 10 .. 14 ps. After some time, this values starts to rise slowly and might grow up to several ns. The effect seems to be temperature related, with the lid removed it takes longer until the unit starts to fail. I used quite some cooling spray, and the front panel board seems to be somewhat sensible, but I couldn´t find a part which, when cooled, returned the display to the initial values.  Cooling the whole frontpanel with an external blower also helps.
> 
> Then I noticed that I am able to bring back the display back to a few picoseconds by switching arbitrary around with the trigger slope switches - both channels seem to have an influence. After flipping them forth and back several times, everything is OK again. I couldn´t find any systematic behaviour behind this.
> 
> Did anyone experience something similar? (and maybe even found a cure?) Any hints will be highly appreciated...
> 
> Best regards,
> 
> Matthias
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