Not sure if this has been discussed, but looks very interesting and I ordered a set:
"
Here you can buy a PCB-Set to modernize a HP 3400A to the latest 3400A Version.
It contains of the following PCBs: A6 Chopper Board from Defpom, A2 Impedance Converter Board
(no further need of the Nuvistor) and the A7 Power Supply Board. With the new A7 PS-Board you
can use silicon transistors not the old germanium types.
?
I'll add information about the new replacment parts and the new schematics to the boards."
