Hello Jared

I haven’t got any data sheets for this OXCO, but there is some info on adjustment in the 3325A manual (page 5.3).?

There is also some info in the ‘Out of whack oven osc in 3325B’ thread about a problem with this OXCO???? I had the same problem adjusting the OXCO in my 3325A as this poster.?? I couldn’t get the coarse external adjustment even close to 10 MHz and the output was unstable.??? Taking the cover off and fiddling with the internal pot fixed it and it has been very stable since? (checked with a GPS disciplined counter).?? It seems a dead spot develops over time in the internal temperature adjustment pot.

Regards

?

Kerry

?

Hi all.
I recently upgraded my 3325A Function Gen with the OCXO option and was looking for any info on the Ovenaire 73-52 OCXO used for this upgrade.

I have the pinouts etc from the 3325A service manual, but does anyone have any data sheets, or adjustment info etc for this part?
I wouldn't mind checking the oven temp adjustment and other stuff inside to make sure it's all working correctly, as well as being generally curious of the specs of this thing.

Thanks!
Jared.

Hello Jared

?

I haven’t got any info on what the internal temperature should be.? Your waveform looks reasonable to me, but others would be better able to judge that than me.? I haven’t checked the waveform from my own OXCO.

?

I seem to remember you had a project a while back to reproduce the high output board for the 3225A.? Did you have any success with that?

?

Regards

?

Kerry

?

?

Thanks for that page number, my OCXO seems to be working well so far, but I'll keep that dead spot issue in mind in case of future problems.
Is there any info on what the actual internal temperature should be set to?

Also, here's a link to a scope screenshot of my output waveform as terminated to 50ohms from the back panel BNC connector, does this look like a reasonable waveform?
https://i.imgur.com/MRJV9MB.png


On Tue, Aug 10, 2021 at 04:29 PM, Tony Cox wrote:

Hi Jared,

?

I added one to my own 3325A a year or two back. It seems to work well. There is a header on the PSU PCB for the ac power supply so it you need to make up a cable and route it across the case to supply it. It is not like the optional high voltage card which has a dedicated AC PSU/supply direct from the transformer.?

?

You also need to supply a short coax “jumper” to connect the oven-out chassis mounted BNC to the Ext Reference In BNC. I don’t think there is an internal way do do it without putting a hack in place. I think HP has a fancy rigid external connector to do this but I could never find one and a short coax does the job.

?

Adjustment is quite easy - I used an external 10MHz reference to calibrate it quite carefully. The manual has a section on doing this. There is a schematic for the board in the service manual - it’s not complicated.

?

Good luck

?

Tony

Luckily I was able to obtain all the parts, including the power cable and that (rare) rear BNC jumper bar, so I'm all set there.
I don't currently have anything more accurate than another OCXO or two that also probably need adjustment, so I do have my eye on a GPSDO, the Leo Bodnar one looks interesting.
But then, I can just connect that directly to the 3325A anyway, at least my gear acquisition syndrome is temporarily sated with the addition of this OCXO to make my 3325A now a fully specced out unit. :D

Thanks Jared

?

I think I’ll hold off for the moment and see if the group buy gets going.

?

Regards

?

Kerry

?

Hi,

I did have complete success with my reproduction of the Option 002 HV output board.
Unfortunately Covid but a big damper on my planned group buy of the kit, but it is still in the pipeline once things start happening again.
If you want to build one yourself before I get to re-organizing the group buy, here's a youtube video on it, plus direct links to all the files:






Regards,
Jared