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_steinm...@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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