[HBR] Mystery cans

[Sandy and Kees Talen]

I think Mike is correct.......

If they have 6 pins in a circular pattern on the bottom,
either solder pins or a mica wafer with 6 sockets, it's
an ARC-5 can (one of the little command sets). If it 
has leads or 4 pins it's something else, maybe military, 
maybe not. Generally a LOT of "old stuff" is war surplus
or comes from war surplus. The frequency should be 
stamped on them. If not, find out what pins the coils are
connected to, hook a signal generator across one coil
and a scope across the other coil (doesn't matter which
one) and see what frequency it peaks at. Or you can 
measure the coil and the resonating capacitor and 
calculate the frequency. ARC-5 cans do have two top 
adjustments but they are (excellent) air trimmers. 

Kees