This is a HP141T mainframe, with a 8554B spectrum analyzer and 8552 I.F. plug-ins. These were about $7000 in 1972 dollars, waayyyy beyond any toy I could have afforded in those days!! It's amazing, 50+ years later, thee things still perform pretty well.
I got this from a friend in the Rockingham area. I did the typical recapping, changing some out of spec resistors and such, cleaning, lubricating various controls, etc. After bringing it up on a variac, the fuses in the 8552 I.F. module kept blowing. Digging into the schematics, I found a crowbar was tripping, due to over voltage from the 141T display unit.
In the 141T, there's a neon Z82R7 lamp with a drop of Krypton 85 that sets the firing voltage at 82 vdc. Yep, radioactive parts... It has a 10 year half-life, and was now firing upwards of 100v, causing the crowbar to crow and blow fuses :-) . I strung a few zeners in series to give me about 82v, and replaced the Krypton thing with more modern tech. All is now well, and this 50+ year old spectrum analyzer is working like new.
