1940s Abbott Instrument Model TR-4 VHF Transceiver



The picture above is of an Abbott Instrument Transmitter-Receiver (transceiver) Model TR-4 from the 1940s. I believe it was used during WWII for the W.E.R.S. War Emergency Radio Service. The transceiver uses amplitude modulation and incorporates an HY-615 vacuum tube functioning as a superregenerative detector and an HY-75 functioning as a VHF oscillator. It has a 6V6 vacuum tube functioning as the amplitude modulator and audio output. It also has a 7F7 vacuum tube for the first audio stage. This unit has apparently been modified and has a 6K6 in place of the 6V6 beam-power tetrode vacuum tube. The transceiver operates in the 2 1/2 meter band from 112 to 116 MHz. Input power is rated at 20 Watts. It operates on 6 Vdc or 110 Vac, 60 Hz.

Below is a picture of the transceiver with its rear panel open.



Below is a picture of an electrical schematic found inside the transceiver. It shows the wiring before a modification made to the audio portion.



Tube Compliment

SuperegenerativeDetector	1st Audio Amp	AF Output/ Modulator	VHF Oscillator
HY-615	7F7	6V6	HY-75