Calibration of HP-8640B Signal Generator
Jeff Weinberg W8CQ
Can anyone on the list near Indianapolis calibrate my HP-8640 OPT323 signal
generator? I don't have a frequency standard to do it against. I do have
the service manual for the unit and would be happy to drive to someones
shack or shop to do it.
Thanks,
Jeff W8CQ
w8...@arrl.net
Scott (Unit 69 Chesapeake Bay)
for checking and setting my frequency counter. Can you zero beat to
one of those?
David Little
The 4 pin oscillators used on computer system boards are a good standard.
Digikey and Mouser have test circuits in their catalog listings. you can
use a rolled collet IC socket with the un-needed pins removed and a zif
socket to make a quick change frequency standard generator.
Old loran C units usually have a very accurate 10 mHz oscillator, and it can
be easily used by taking a hacksaw blade and cutting the section of the
circuit board loose, mounting some rubber feet, supplying input voltage and
output connector.
I also have a 8640b Opt 323. It is a good unit, but doesn't have the high
stability option, and can drift until warmed up. Ambient temperature in the
operating environment can extend the warm up time. Even after warm-up it
may still have a tendency to drift.
Component aging could be a factor, and will call for continued "correction"
until they fail completely. Replacing the failing component may result in
no alignment needed, and would be the best approach if isolation is possible
for replacement.
How big is the manual (in terms of pages), and where did you get it? I may
have to undertake the same process you are looking to one of these days.....
David
KD4NUE
Scott (Unit 69 Chesapeake Bay) <upp...@hotmail.com> wrote in message
news:3A2DCE06...@hotmail.com...
tom_b...@agilent.com
"David Little" <dali...@sprynet.com> wrote:
> Scotts suggestion is a good one to use as a standard.
>
> The 4 pin oscillators used on computer system boards are a good
standard.
... I'm sorry but I really have to take issue with this. The typical
oscillator can used in digital/computer systems has, at best, a 50ppm
tolerance. I would certainly not call that a "good" standard. I assume
the 8640B/opt323 at least has a counter, and the timebase for that
counter is undoubtedly capable of quite a bit better than 50ppm when
it's warmed up. If I remember correctly, the opt323 deletes the phase
locking, and if that's the case, of course the osc will drift some.
I've heard of folk adding the circuits to do the phase locking, and that
seems worthwhile if you want good stability over time.
If receiving WWV is a problem, one might consider seeing if Douglas
Dwyer (who has posted here in the past, I believe, or at least over on
sci.electronics.design) still has inexpensive surplus high quality
oscillators available. A "deja" search should find him easily.
According to what NIST publishes, you shouldn't count on doing better
than about 0.1ppm with WWV, but my experience with an 8640M (with
oven-controlled oscillator) is that it's not stable to much better than
that anyway.
Cheers,
Tom
--
Tom Bruhns -- K7ITM
Sent via Deja.com http://www.deja.com/
Before you buy.
Robert S. Stein
>
> In article <90kpuv$obr$1...@slb1.atl.mindspring.net>,
> "David Little" <dali...@sprynet.com> wrote:
> >
> > The 4 pin oscillators used on computer system boards are a good
> standard.
>
> oscillator can used in digital/computer systems has, at best, a 50ppm
> tolerance. I would certainly not call that a "good" standard. I assume
> the 8640B/opt323 at least has a counter, and the timebase for that
> counter is undoubtedly capable of quite a bit better than 50ppm when
> it's warmed up. If I remember correctly, the opt323 deletes the phase
> locking, and if that's the case, of course the osc will drift some.
> I've heard of folk adding the circuits to do the phase locking, and that
> seems worthwhile if you want good stability over time.
>
> If receiving WWV is a problem, one might consider seeing if Douglas
> Dwyer (who has posted here in the past, I believe, or at least over on
> sci.electronics.design) still has inexpensive surplus high quality
> oscillators available. A "deja" search should find him easily.
> According to what NIST publishes, you shouldn't count on doing better
> than about 0.1ppm with WWV, but my experience with an 8640M (with
> oven-controlled oscillator) is that it's not stable to much better than
> that anyway.
>
> Cheers,
> Tom
>
I too have an 8640B-323. Do you have any idea where I can find info
on adding the phase-lock ciruit used in the commercial version?
Does anyone have a manual for the commercial 8640B who could copy the
schematic(s) of the phase-lock circuit? That might be a good starting
point.
Bob, W6NBI
Robert S. Stein
>
> In article <90kpuv$obr$1...@slb1.atl.mindspring.net>,
> "David Little" <dali...@sprynet.com> wrote:
> >
> > The 4 pin oscillators used on computer system boards are a good
> standard.
>
> oscillator can used in digital/computer systems has, at best, a 50ppm
> tolerance. I would certainly not call that a "good" standard. I assume
> the 8640B/opt323 at least has a counter, and the timebase for that
> counter is undoubtedly capable of quite a bit better than 50ppm when
> it's warmed up. If I remember correctly, the opt323 deletes the phase
> locking, and if that's the case, of course the osc will drift some.
> I've heard of folk adding the circuits to do the phase locking, and that
> seems worthwhile if you want good stability over time.
>
> If receiving WWV is a problem, one might consider seeing if Douglas
> Dwyer (who has posted here in the past, I believe, or at least over on
> sci.electronics.design) still has inexpensive surplus high quality
> oscillators available. A "deja" search should find him easily.
> According to what NIST publishes, you shouldn't count on doing better
> than about 0.1ppm with WWV, but my experience with an 8640M (with
> oven-controlled oscillator) is that it's not stable to much better than
> that anyway.
>
> Cheers,
> Tom
>
I too have an 8640B-323. Do you have any idea where I might find
information on adding the phase-lock circuit used in the commercial
version of the 8640B?
Does anyone have a copy of the commercial 8640B manual who could copy
the schematic(s) which show the phase-lock circuit?
Bob, W6NBI
tom_b...@agilent.com
believe the M is essentially just a repackage of the full-blown B.
There's almost certainly a B manual around here, too. I contacted a
friend who I thought had added phase locking to his 8640Bopt323, but
turns out he had found non-braindead 8640B's so never did it. I'm
willing to do some manual photocopying, and if there are several folk
interested, the copying could be a lot more efficient than if it's just
one-off.
Cheers,
Tom
In article <3A2F1354...@jps.net>,
"Robert S. Stein" <rst...@jps.net> wrote:
> I too have an 8640B-323. Do you have any idea where I can find info
> on adding the phase-lock ciruit used in the commercial version?
>
> Does anyone have a manual for the commercial 8640B who could copy the
> schematic(s) of the phase-lock circuit? That might be a good starting
> point.
>
> Bob, W6NBI
>
--