Pilbeam Engineering

Some years ago, I bought a 1929 Atwater Kent model 67 radio receiver & matching speaker. The Model 67 was a battery powered (for non-electrified areas) AM TRF receiver. It utilized an electro-dynamic (field coil based) speaker. I initially acquired an ARBE-III battery eliminator for the set to get it operational. With a battery receiver, it’s much easier to “plug and play” since there’s no AC power supply circuitry to be concerned with: the requisite voltages are delivered directly to the circuits through several wires.

After 76 years, the color coded wiring had faded and I had a hard time determining which wire got the +5V and which got the +135V, but I got it right the first time…and powered up the unit. It slowly came online, as though waking from a long sleep…but there was no sound! I cranked the volume control, and faintly heard voices – but they were distorted, as though the audio amplifier were being overdriven though the sound was still very low. 

After making some inquiries, I found out that very likely the audio interstage transformers were bad…so I melted them out of the chassis-mounted cans that they rest in…and pretty much left it at that. Now, some years later, I’m ready to start again. I spent Saturday tearing down the chassis as far as I could, taking it out of it’s metallic case, and scrubbing it with metal cleaner, and also oiled the ancient air-dielectric tuning capacitors. The pictures that follow give evidence of my work:

[photoxhibit=4]

Additionally, though looking at schematics and wiring diagrams available on Nostalgia Air I was able to determine the specifications of the original transformers…and after inquiring at the ARBE-III site (where they also provide equivalent transformers for early Atwaters), I now have two transformers on order…and Pt. 2 of this topic will be covered when they arrive and the unit powered up.

-Adam