While digging out my HP 5005A, I ran across these interesting old boards deeper in the box of assorted parts, can anybody ID them or at least suggest a function? Mods- Hope this is the right forum for this! 1-4 are the largest board, 5-7 are the smaller board, and 8-10 are the smaller board that is a reduced version of 1-4. Neons, barrel-caps, disc-caps, resistor-networks(?), and an adjustable thing in a can, either an inductor or a capacitor. The numbers on the boards don't get me anything in google, so I know it's old! They have several other markings 'BAL-5', 'IK', 'B 177' 'B 164', 'B 156', and 'B 221'.

Capacitor marking 7032 probably means 32nd week 1970, so that gives us an approximate time period!