[time-nuts] Questions about HP 5370B

Bruce Griffiths bruce.griffiths at xtra.co.nz
Tue Sep 14 07:28:55 UTC 2010


Charles P. Steinmetz wrote:
> A friend just received an HP 5370B that was said to be properly 
> working and accurate, and asked my opinion.  I'm not familiar with 
> these, so I thought I'd ask the experts.  All we've done so far is 
> hook it to a Tbolt that I know is operating properly.
>
> The 5370B took hours (8 or so, which seems like a long time for a 
> 10811) to drift to a reasonably stable reading, a bit over 100 Hz high 
> (which seems like an awful lot for a 10811, even after a trip across 
> the country ten years since its last calibration).  The front-panel 
> oven indicator is off; I did not notice if it was on when we first 
> powered it up.  The 5370B reads its own oscillator within spec (< 2 
> mHz error; spec is +/-5 mHz).  We have not opened it to tweak the 
> oscillator (or to verify that the 10811 is, in fact, still present).
>
Open the lid and check that it actually has a 10811A rather than a 
simple gate oscillator.
> Timing seems to work OK, giving the expected 100 nS and 50 nS figures 
> when I feed the internal oscillator into the start input, tie start to 
> stop (START COM), and switch the trigger phase of the stop channel.
>
> Finally, the external heatsink (left rear) runs pretty darn hot -- 
> somewhat warmer than you'd really like to leave your hand on, which is 
> WAY warmer than I'd ever design.  Concerning (to me), but not 
> completely beyond reason.  I suppose it could be normal for these.  It 
> didn't burn down or shut off during the 8 hour warmup.
>
The heatsink does run hot.
> I appreciate any input from those knowledgeable about the 5370B.
>
> Thank you,
>
> Charles
Bruce




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