[time-nuts] Re: Software for Agilent 58503a

[paul swed]

I do see it never goes above 10 MHz. Assuming 992 is 0 volts
Have taken a Z3801 oven apart its quite a job.
Suggestion insert voltage from a very stable power supply through a 10 turn
5K pot and see what voltage is required to get to 10,000,001 Hz.
If its not a lot more, then an offset voltage using a summing opamp may
solve the issue if you simply can not get into the oven.
Granted a coarse adjustment in the oven would be far better.
Paul
WB8TSL

On Fri, Nov 8, 2024 at 3:47 PM rbenward--- via time-nuts <
time-nuts at lists.febo.com> wrote:

> Hi Bob,
>
> Sorry for the delay, I just got back from vacation.  As you suggested, I
> shorted the EFC input and got xxx992Hz.  Then I put 5V, 0V, and -5V on the
> EFC.  As you can see, it’s never going to make it, it’s just too far off
> (assuming and EFC range of +/-5V).
>
>
>
> I know somewhere there was post or an article about drilling a hole for
> the adjustment, but I just can’t find it.  I really would like to know how
> they dealt with not perforating the heater wrapped around the inner can.
>
>
>
> Bob
>
>
>
>
>
> 5V
>
>
>
>
>
> 0V & short
>
>
>
>
>
> -5V
>
>
>
>
>
> -----Original Message-----
> From: Bob Camp via time-nuts <time-nuts at lists.febo.com>
> Sent: Thursday, October 17, 2024 4:29 PM
> To: Discussion of precise time and frequency measurement <
> time-nuts at lists.febo.com>
> Cc: rbenward at verizon.net; Bob Camp <kb8tq at n1k.org>
> Subject: [time-nuts] Re: Software for Agilent 58503a
>
>
>
> Hi
>
>
>
> Simple check:
>
>
>
> Let the unit warm up for a while ( > 30 minutes, 2 hours would be better).
>
>
>
> Put a frequency counter on the output of the 10811.
>
>
>
> Short the EFC to ground.
>
>
>
> A working “GPSDO version” of the 10811 should have about +/- 1 ppm of tune
> range. With a shorted EFC anything within a half ppm of 10 MHz should be
> “ok”.
>
>
>
> Bob
>
>
>
> > On Oct 17, 2024, at 11:00 AM, rbenward--- via time-nuts < <mailto:
> time-nuts at lists.febo.com> time-nuts at lists.febo.com> wrote:
>
> >
>
> > Hi Tom,
>
> >
>
> > Thank you for the link, I searched and searched but I got nowhere.
>
> >
>
> > I haven’t played with my equipment in almost 15 years.  I need to get
> back into it.  For instance, you mentioned the heater.  One plug which goes
> to the power supply on the Z3805A has two wires disconnected.  I probably
> did that, or it came that way, I just don’t remember.  This unit used to
> work but not anymore.  Everything checks OK (status) except for the EFC.
> On the Z3801A (my first GPSDO) I had taken it apart and put it back on
> frequency, but of course, the adjustment is with the oven taken apart down
> to the 10811 level.  I don’t know what the limits are, and certainly did
> not know where the EFC was or which way it will drift when re-assembled.
> Currently both units show the EFC at the rails, so I am assuming for now,
> that the oscillators have drifter too far and they need a push back to the
> center.  I would like to convert these two paperweights back into working
> units.
>
> >
>
> > My Trimble is working fine but I don’t know how long that will last.
>
> >
>
> > I am off for three weeks, so all this effort will go on hold until I get
> back.
>
> >
>
> > Thanks for your help,
>
> >
>
> > Bob
>
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>
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