Sound-Powered Telephone Spotter's Guide

Here are a few of the commonly seen sound-powered telephones that are useful for crystal set purposes. Elements generally have a nominal impedance of 600 ohms. Wire in parallel for 300 ohms or in series for 1200 ohms. You'll need a transformer that matches this low impedance to 10K ohms or more. 100K is very desirable.

Field Testing: If you put one of these to your ear, you'll be able to hear yourself. If you're not sure, short the input lead, which will kill the signal. This does not apply to the TA-1/PT. The push to talk switch disconnects the receiver in this phone.


US Navy "Deck Talker": Actual nomenclature is unknown. The frame detail around the earpiece is a dead giveaway. These are highly desirable as they already have a headband and two earpieces. You'll most likely want to disconnect the breast plate and microphone. Install the mic element in your antique horn speaker for improved performance.


US Army Signal Corps Handset TS-10: These were made by many different manufacturers. Some use the same element for both transmitter and receiver. This means you can make a headset from a single TS-10. Others use dissimilar elements. The transmitters are usable as receivers, so don't throw them away. However, it's best to have a matched pair. The rounded shroud over the mouthpiece will help you identify these at a distance, but some none-sound-powered phones have a similar configuration. Some examples include a push-to-talk switch.


Telephone Set TA-1/PT: This is an entire magneto type field phone built into a handset. The transmitter and receiver elements are dissimilar. The elements are less sensitive than the others shown above, but still better than common headphones. The elements are small enough to fit inside Baldwin Type-C cases. These phones tend to sell for about $30 so they're not such a great deal. Receiver elements are labeled TA-118/PT. You may find some in miiltary surplus channels.