Hello all,
I recently upgraded my HP 5335A (S/N 2044Axxxxx) from the standard internal crystal to the 18011-60111 OCXO (Option 010). My unit came equipped with the standard oscillator crystal, but with a card edge connector for the OCXO already built into the A4 board. The two mounting holes for this assembly were pre-drilled in the board. The correct service manual for this serial number is 05335-90021, which states that the correct OCXO for this SN is 18011A. Mine was a 18011-60111, so that's the one I installed.
Jumper W1 on circuit board A4 must first be removed in order to enable the OCXO operation. This jumper looks like a 1/8 W resistor, but the parts list shows it as a 22 gauge wire jumper. I carefully cut and lifted one end of this jumper.
The 10 MHz crystal should then be removed in order to avoid any possible interaction with the new OCXO. This crystal is in a TO-5 case (HC-35/U Mil) and has 3 leads, just like a TO-5 transistor. After much probing around in there, I discovered that the crystal was NOT soldered in, it is merely pushed into a special socket on the cirduit board. From the top of the board, I was able to work it up and out of the socket quite easily. I was able to get the part number for this crystal from the parts list in my manual, and did a Google search. I located another piece of equipment that uses this same crystal, and this manual listed several manufacturer sources for it. The Bliley Crystal website had the specifications for it, the BK3-1B-10MHz, and I am attaching a .pdf of those specs for anyone interested. (Note: the socket for this crystal is easily mistaken for a triangular grouping of solder blobs. A closer look reveals tiny holes in the center of each blob, to accommodate the crystal leads.)
I first installed the older 10544A OCXO which also worked just fine in my counter, but since I also had the more stable, newer 18011-60111, I settled on that one.
I want to thank Dr. Frank (this Forum) for his kind assistance in this project. I wish to also thank EEV contributor max_torque for the photos contained in his post of May 23, 2014 regarding the HP5335A. I took the liberty of re-using crops from two of these photos of board A4 to help illustrate this project. I hope you don't mind.
Best wishes to all,
Wade
NW IL