These were used to increase the reach of phone lines. The neat thing is that it's an amplifier that amplifies the signal between A and B as well as the signal between B and A, that's to say each terminal pair is both an input and an output. For this to work the lines need to have the same impedance looking each way from the amplifier. The functional check is to short either the input or output and listen on the earphone to see that the amplifier is oscillating at all attenuation settings.
There are two ways to power this repeater: either use a BA-40 combined 1.5 & 90 Volt battery by means of the 4-prong plug, or use seperate BA-23 (No. 6) 1.5 V battery and two BA-36 45V batteries in series by means of the 4-prong socket to 4-wire cable.
The single tube is the VT221 (3Q5GT). There's a single Trimm earphone to monitor conversations going in either direction.
To test operation just short either pair of line terminals and there should be oscillation at all settings of the attenuator.
Normal 20 Hz ringing can be employed on lines equipped with these repeaters. Ringing signals are transmitted through the repeater.
Made when W-110-B was the common filed wire, but will work with WD-1 field wire.
Fig 1 Overall view
Signal Corps U.S. Army
Fig 2 Instructions & Circuit
Fig 3 Battery Box & Front Panel
Fig 4 Front Panel
Fig 5 Inside top left
Fig 6 Inside back right
Fig 7 Inside Bottom
Short Line A terminals and hear if the unit sings into the earphone at all attenuation switch settings.
- Connect EE-8 field phone to Line A and speak into handset. E-89 headphone should produce speech.
- Check for continuity between top Line-A and top Line-B also check between bottom Line-A and Line-B. Both should be between 35 to 45 Ohms.
- Voltage check at tube socket. Between filament pins 7 & should be about 1.5 VDC as well as between 2 & 8. Plate voltage between pin 3 & 8 should be at least 80 VDC.
- TM 11-4407 contains tests for the major components as well as line impedance tests to verify the hybrid coil is working.
TM 11-2006 July 1943 Operation, Moistureproofing &
TM 11-4301 General requirements of repaired equipment (not E-89-A specific)
TM 11-4302 Tactical Switchboards and Long Lines Equipment, Repair Instructions, Apparatus Requirements
TM 11-4407 Aug 1945 - 4th & 5th echelon repair - Repair Instructions, Operational Requirements & Testing (Note: This is a War Department manual)
SB4170 Military Telephone Switchboard
GRA-39 Radio Set Remote
Z0 - transmission line impedance including CAT5 and Open wire telephone lines
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page created 2 Oct 2013