Following shortly on the heels of both of these, radioteletype began to move forward, although by the late 1930s it was still considered too new a form
of wireless communication to be taken into account as a possible future battlefield communication platform. Instead, wire telegraphy was the dominant communication form for the battle field, with the six-pound manual telegraph set TG-5 being one of
the most prolific items in use up through and well into World War II.
Part of the reason for reliance on telegraphy versus telephony came from the fact that the voltage of telegraphs like the TG-5 could be increased
in order to drive the signal out over a greater length of wire, or to compensate for poor wires that might suffer from high resistance points
along the length of the circuit. This could not be done with telephony, which required a rather precise voltage level, thus making telephone units
less reliable in field locations. Add to this the fact that interference had less of an effect on a telegraph signal than on voice communication,
and the fact that while telegraphy required a trained operator the enemy at least needed one too, as well as one who spoke English and knew Morse code, and it was
easy to see why most military commanders trusted their front line communication to telegraphy.
The TG-5-B seems a bit over designed for a telegraph set, but this is the way they built things in those days.
The orange stamp on the cover is a Signal Corps acceptance stamp.
The key attached to the front cover is a J-41-A .
Manual telegraph set consisting of telegraph key, line relay, oscillator (howler) and telephone headset.
Is equipped with a "call" bell. When headset is connected, the oscillator provides a tone in the headphone receiver of about 1000cycles which is under control of line relay.
Line relay operates on about 1,5mA and has air-cap and spring-tension adjustment.