[time-nuts] 5370A

Joseph Gray jgray at zianet.com
Sat Oct 10 23:41:08 UTC 2009


Greg,

I plan on doing the A3/A4 adjustments. I just don't know where I'm
going to get a pulse generator or the fancy scope with the 1GHz
sampling plugin. Not the type of equipment on your average test bench.


On Sat, Oct 10, 2009 at 5:03 PM, Greg Burnett <gbusg at comcast.net> 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".)
>
> 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
>
>
> ----- Original Message -----
> From: "Joseph Gray" <jgray at zianet.com>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Sent: Saturday, October 10, 2009 2:23 PM
> Subject: Re: [time-nuts] 5370A
>
>
> Greg,
>
> Yes, the trigger levels are near zero when the LEDs are flashing. The
> level pots are both at 1 o'clock, instead of 12 o'clock, however.
>
> There does seem to be a problem with the preset trigger postition.
> Although the display shows 0.00V when at preset, I don't think it is.
> When I manually set the levels to 0.00V, the TI shows 100nS. At preset
> levels, the TI is noticeably higher.
>
> Joe Gray
> KA5ZEC
>
>
>
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