HP 3406A Millivoltmeter [SOLVED]

[RF-Engineer]

HP 3406A RF Millivoltmeter wanted that actually passes the 1.0V calibration test with the probe inserted into the CAL test jack.  Most don't.  Reply with actual photo of the unit in the CAL position with the probe inserted and the 3406A on the 1 V scale.  In return, I will make a generous offer if it really passes. 

[Zucca]

https://www.keysight.com/us/en/assets/9018-02640/user-manuals/9018-02640.pdf

Mind-blowing how much details were in a manual back in those days...
Operating and Service Manual in one document... I miss those days so much....

[RF-Engineer]

I can call off the cry for help with a purchase.  Today, I buckled down and began looking at the sampling probe of an HP3406A that had been shelf-bound. 

Starting at the probe tip, I discovered that one of the Schottky bridge diodes had failed shorted.  A 1N5711 is a temporary replacement.  For a permanent fix, I ordered a sleeve of Avago/Broadcom HSMS-2828 quad bridge diodes, the benefit being a matched set of diodes on a single substrate. 

As these RF millivoltmeters get passed around with time, invariably someone applies way too much input voltage to the probe -- and there it sits until it's sold to someone like me. 

Paul