The TBL transmitter combines LF/MF/HF in one
package. Frequency coverage is 175-600kc and
2-18.1Mc. It uses 2 860 master oscillators, 860
intermediate amplifier, 860 modulator, and a pair of 803s in
the final amplifier giving a rated power output of 200W CW,
100W MCW(LF/MF only), 50W AM. Aside from the
master oscillators, tubes are shared between the LF/MF and HF
(2-18.1Mc). It can be split into two units, making it
narrow enough to load through a 20 by 25-inch hatch as on a
The TBL is powered by a seperate
motor-generator unit. A controller unit starts and stops
the motor-generator. There are at least two different
speech input units designed for the TBL.
Mine is a TBL-5, CAY-52133 made by
Westinghouse, with a contract date of 22 Nov. 1939.