[time-nuts] HP Z3816A – no 10 MHz output / need info on feed point

[David Radecker]

Hi everyone,

I’m currently working on an HP Z3816A that originally had a faulty OCXO.
I'm trying to repair the oscillator itself now, but I’m running into a problem: on my board the RF-OUT pin of the OCXO is completely unconnected - no trace, no jumper, nothing.

The unit should double 5 MHz to 10 MHz somewhere on the board, but I’m unsure where exactly the feed point is located and how the OCXO is normally wired into the chain.

I found the modification blog on xertech.net, but I did not perform that mod - I only used the photos for reference. Unfortunately, I can’t see the OCXO area from the bottom side.

Does anyone here have bottom-side photos of the OCXO area, or information on where the RF-OUT pin is normally routed?
Any hints or images would be extremely helpful.

Thanks in advance!
David