[time-nuts] Questions about HP 5370B

[paul swed]

I have picked up a few of these over the years.
Seems almost everyone knows to take the oven.
Or the low quality gate oscillator is in there. Worthless and can easily be
100Hz off.
Very touchy.
Great advice from the group to check various supply voltages.
Agree on the heat sink. Its hot. Some one mentioned they added a small fan.
I intend to do that to several of mine especially the one I use all the
time.
One day. ;-)
Good luck good counter.

On Tue, Sep 14, 2010 at 8:19 AM, Bruce Griffiths <bruce.griffiths at xtra.co.nz
> wrote:

> It doesn't use IC regulators.
> It uses a common IC reference together with a few opamps and discretes.
>
> Bruce
>
>
> Bob Camp wrote:
>
>> Hi
>>
>> In an earlier thread on the 5370B checking the voltage out of the
>> regulators was mentioned. If you are going to open the counter up anyway,
>> putting a DVM on them is probably a good idea. They do run hot and some
>> eventually drift way out of spec. Cheap part to replace if it's bad..
>>
>> Bob
>>
>>
>>
>> On Sep 14, 2010, at 3:12 AM, "Charles P. Steinmetz"<
>> charles_steinmetz at lavabit.com>  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).
>>>
>>> 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.
>>>
>>> I appreciate any input from those knowledgeable about the 5370B.
>>>
>>> Thank you,
>>>
>>> Charles
>>>
>>>
>>>
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