HP 202C Low Frequency Oscillator

[Findm-Keepm]

The 1uf coupling caps can get leaky, cutting off the output tubes, and reducing the output. I changed quite a few as a cal tech in the Navy, 200cd, 202's, lots of em. The Navy used them as audio oscillators to test airborne intercom systems and some sonar equipment.

Make sure the Wien oscillator "bulb" has continuity. it's socket will oxidize and cause troubles. I seem to recall them being 7w 120v candelabra based bulbs, and we're made by GE for HP. if you go probing, use a high impedance probe, else you can kill the oscillator action with probe loading. I'd start at the grids of the outputs, and if it dies there, you can rule out the output tubes and attenuators section.