Addendum

19 Set Layout and Details - Churchill Tanks

The first British AFV to be equipped with a radio was the AIE (Independent Experimental) Tank introduced in 1925 - additional to the radio it was also the first to have an inter-communication system. However, it wasn't until the introduction of the 7 Set in 1935, followed by the 9 Set in 1939, that a reliable means of communication between tanks became a reality. As can be seen in the photograph below, of South African Mark II Light Tanks in Egypt, a problem not solved until the 19 Set came along, was the rigid stout antenna easily visible to hostile eyes when in a turret down position - not helped by the flying of pennants!

Copyright photograph reproduced courtesy Imperial War Museum

The 19 Set was developed in 1941 and was standard equipment on all Churchill Marks. It was mounted on a ledge at the rear of the turret along with boxes of spare valves and other replacement parts. Improvements, enhancing the set's performance were from time-to-time introduced, especially when production commenced in Canada. The introduction of the Churchill Mark VII saw the additional mounting of a 38 Set in order to better to communicate with ground forces.

The 19 Set has two components, known as the "A" Set (on the right) and the "B" Set, the former providing intercom via control boxes. The photograph is of the Canadian built Mark II set which later replaced the British built Mark Is.

.
A-Set
B-Set
Frequencies:
2-8 MHz
230-240 MHz
Function:
Speech + MCW *+ CW **
Speech
Range:
10 miles with 8 ft Aerial †
1,000 yards ††
Antenna:
Whip - 3 x 4 ft Sections
Flex - 20½ inches
Antenna Base:
Number 8
Number 9

Notes:
*   MCW: Modulated Carrier Wave. Used for audible Morse Code transmissions.
**  Carrier Wave. Used for inaudible Morse Code transmissions.
†   This range varied considerably, especially while the Heavyside Layer was      descending.
†† The 1,000 yard range is an approximation. As B-Sets transmit by ground-wave      they can only connect between tanks visible to one another.

The Intercom Amplifier was controlled by two boxes, placed on either side of the turret, available for use by both the commander and operator. There was an ongoing problem with the system when, in the heat of battle, a commander would tie up the net by forgetting to set the switch on the Control Box in the proper position. 1944 saw the introduction of a modification to the Control Boxes, which permitted the Intercom to be used regardless of the switch position provided the microphone/headset unit, if the "Pressel" Switch was not pushed down. This feature lessened the problem to some extent, however, it was not finally resolved until the installation of telephones in later Churchill Marks. 10 and 20 foot extension cords were issued in 1944, which, when added to the operator's, allowed the use of his headset by someone ouside the tank to communicate to the commander.

All in all, the 19 Sets were reliable and worked well, operators being assisted with a detailed problem solver in the 19 Set Hand-book:

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