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

[Bob Camp]

Hi

It’s close enough (within about one ppm) that’s it’s not an oven failure. Since it is 
frequency low, it might be a crystal seal failure / leak. That’s not something you can
repair short of replacing the crystal. 

Since it *is* tuning it is not an EFC short / failure. That takes another fairly simple 
repair off the list. 

I’d just replace the whole OCXO. Typically I buy them on eBay for < $60. The outer heater does nothing useful unless your shack runs below freezing. Pretty much any
10811 should do the trick. The trim range might be a bit less. That may be a good thing. 

Bob

> On Nov 8, 2024, at 3:41 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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