Products > Test Equipment

HP 5316A Teardown and Frequency Standard

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Luthor2k:
A second PCB is going out tomorrow. There are two remaining and parts minus the trim pot.

Luthor2k:
Only two boards remaining now!

Luthor2k:
I received a questing from someone about the TCXO board install in my counter and thought I'd repost here for all:

"I have a question about  mounting and using the OXCO board in the HP 5316B. Many of the users of the board were using them in a 5316A. There are significant differences in that earlier model. I know you have a "B" model too, and your posted photo is in that unit. Apparently the "A" model had an external factory oscillator, so it was a matter of removing that board, and plugging in the replacement. In my unit, (and I assume yours) there is a crystal oscillator soldered on to the main board that supplies the 10MHZ reference sinewave. I don't know if the replacement board will mount over that factory crystal, or if I need to desolder it from the main board prior to installing the new board in the socket. I'm not sure if the firmware detects the oscillator and switches to it, ignoring the on board oscillator?

My on board crystal actually has a zip tie holding it down tightly to the main board , in addition to the fact it is soldered to the PC board. Did you desolder your factory crystal prior to installing the OXCO board, or is yours mounted over the on board crystal?"

My answer to this is; nope, nothing desoldered! I did however remove an oscillator board from my counter. A photo of the board I removed is attached. During the process I also replaced the two large electrolytic power supply caps. Nothing else was changed.

pinpassion:
Hi Gang,

There is something I wanted to clarify on my particular HP 5316B counter. I think I may have a later unit then some or all of the posters so far wishing to add a OCXO oscillator board to their unit for added accuracy and stability. My "B" model does not have a daughter board as a factory internal oscillator. It has an on-board crystal soldered and secured to the main board with a zip tie. To the best of my knowledge, this is a factory installed crystal, and my unit never had an oscillator as an external board to the main unit. I am including pictures of this crystal on the main unit in both top and bottom photos. Seeing is believing..My unit serial number is 3005A07XXX.

I am wondering if I need to desolder this crystal to remove the 10MHZ signal, or if the firmware will recognize the external board plugged into the  6 pin connector and switch to it's signal for calibration? The crystal is mounted directly over one of the mounting holes for the daughter board, but i could use an alternate mounting arrangement if needed for the replacement OCXO. I will remove the crystal if i have to, but would prefer to leave it there if I can.

Also, if anyone has the feet that were mounted to the cabinet bottom and are willing to part with them, please let me know. My unit was rack mounted, so they are missing. I especially would like the front feet that had the swing down bail for elevating the front off the bench.

Thanks,

Mike

Luthor2k:
Hey Pinpassion, attached is a photo of my counter, no 10mhz crystal to be found. Perhaps chase the trace? Those 4-pin XOs have low Z outputs IIRC...

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