[time-nuts] 5370A

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Oct 10 23:56:00 UTC 2009


Greg Burnett wrote:
> Joe,
>
> I think 1 o'clock (instead of 12 o'clock) might still be OK and/or typical? 
> Maybe some other 5370A users can tell us where their Trigger Level pots are 
> pointing when centered for triggering on a weak signal. (The pots point to 
> 12 o'clock on my 5370B, but I can't remember exactly where they might point 
> on a typical  "A".)
>
>   
My 5370A triggers on the frequency standard output on either the START
or STOP inputs set to 10x attenuation when the Level setting knobs are
at the ~1 oclock position.
The average of the threshold settings when the trigger level is just
above and just below the point at which the trigger light flashes is
20mV or less.
Not a particularly precise measure as it depends on the waveform symmetry.
Both channels trigger (10x input attenuation switched in) on the
frequency standard output when the the threshold is preset.
It is unfortunate that their is no readout of the EXT arm input trigger
level although there is a trigger LED.
> I do know that some of the 5370A A3/A4 Input Amp & Schmitt Trigger I.C.s 
> developed "I.C. rot" many years after manufacture (due to a contamination 
> problem during manufacture). For units so afflicted, the symptom was that 
> "Preset" trigger level was no longer correct, but the trigger level could 
> still be successfully set manually. For these cases, as the years progressed 
> (and the "rot" worsened), you had to turn the manual trigger level pot 
> further and further to one direction to find trigger. As the years of 
> deterioration continued, there came a point where both trigger level 
> setability and sensitivity were no longer acceptable.
>
> If you have only a small trigger level issue in "Preset" mode, my thinking 
> is that you can still correct for it by doing the A3/A4 input adjustments.
>
> Best,
> Greg
>   

Bruce




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