US Navy WWII (WW2) Deck Talker Headset Type R17T23

Sound Powered Phones have Balanced Armature elements, most often previosly used as US Navy WWII (WW2) Deck Talker Headsets. They are ideal for crystal sets. Even Baldwins which are the “Gold Standard” of the vintage headsets do not come close to Sound Powered headsets. Some units do not perform well for music because they are optimized for voice. Together with a special microphone as a head set they allowed speech between different persons without any electricity.

Two basic types of units were used by the Navy, “Deck Talkers” which were a headphone and chest mic unit for spotters and gunners, and handsets which resembled a telephone handset. By the way: The microphone unit can also be used as “ear” piece.

Some fire departments use sound powered units today because they can be used in areas which may contain explosive gases without the fear of a spark setting the gases off.

The only disadvantage for crystal radios is the low impedance which has to be matched to the detector using matching transformers to optain high sensivity without loading the radio's circuit too much. The other method is to rewind them with very thin wire (0.04 mm) to obtain up to about 5500 ohm DC as shown here (most in German)..

See the article in English about rewinding the DLR-5.

Here you find 1 models, 1 with images and 0 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Automatic Electric Company (AE); Chicago Ill.