Quote:
Originally Posted by Neil Ashley
Although not a standard fitting in Armoured Cars, I wired one of these boxes into my Humber Armoured Car. A very good safety feature.
The Drivers IC Box also contains a Transformer and uses a Tannoy Mic and Head Set so from memory he can also reply to the Commander.
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It depends on the IC box, which in turn depends on the number of slip-rings in the rotary base junction (in tanks) and also the design date for the setup.
Early intercom systems used Junction Distribution No.1 (with 'Call Commander' button and buzzer) which had a transformer for the carbon microphone and used Headgear No.2 (standard headset but grey metal 'Tannoy' microphone.
If more headsets were needed (Co-Driver, etc.), Junction Distribution No.2 was added (again with the transformer and using the carbon microphone, but no buzzer or call button).
Both of these required 12V and an earth connection, plus the 'Speech' and 'Signal' wires that came from the WS19 control units, into the set itself, then out via the supply unit to the turret junction box, then via the rotary base junction into the hull.
Later tanks had more circuits available via the rotary base junction, and so Junction Distribution No.3 and No.4 were introduced (as the equivalent of No.1 & No.2) which used the standard headset with dynamic microphone. (This simplified things from a production and operation point of view. Plugging a dynamic microphone into JD1 or JD2 got you a working headset but nonfunctional microphone. Plugging a carbon microphone into the WS19 control box likewise didn't work at all on the IC position, but (due to the wiring differences) got you a ridiculous audio level on A or B set transmit (because the carbon microphone was then connected to the relay line (via the pressel switch) and then earthed through the microphone transformer primary, giving an absolutely HUGE audio output compared to the expected dynamic insert - do not do this, it's bad for your ears.)
The Emergency Crew Communication System was retained, and the commander had a Tannoy microphone (identical to those used on the ALS gun control speakers) that plugged into the transformer unit, and would operate even if the intercom amplifer was switched off or nonfunctional. (Depending on where it received its 12V supply from it may even work if all the tank electrics were switched off, as long as battery power was available!)
It survived into the modern era, and an equivalent existed (using the same 3-pin connector) with the 'Larkspur'/New Range sets. (As did the later version of the Tank Telephone system with the spring-loaded reel - originally with a snatch socket and matching moulded rubber handset sporting two microphone inserts(!), then the green 'Larkspur' plastic handset, and finally the black plastic 'Clansman' type. Apart from the handset, the only thing that changed was the replacement of the 'call buzzer' with an electronic audio tone generator equivalent. Someday I'll get one of those, (hopefully with the buzzer) but but whenever I've seen them I've had too much to carry or they've been in 'Job Lots' and I only want a couple (or three, one with buzzer and snatch socket, and one each Larkspur & Clansman).)
(Right now I have Too Much Clutter and neither the time nor the space to sort it all out. I'm working on this.)
I know I have one each of the WW2 and 'New Range' ECCS boxes, if I've got (or spot) a second WW2 one I'll put it aside for Tim (for whom I'm still trying to find a spare aerial feeder tab washer to go with his base and mount).
Chris.