Wireless Set No. 18 was a man pack transmitter-receiver developed in 1940 for short
range communication in forward areas between Battalion HQ and Company HQ. Frequency
range 6-9MHz. MO control. RF output 0.25W. R/T, CW. Range up to 10 miles. Wireless
Set No. 68 was similar but with different frequency range, crystal control option
and minor mechanical changes. Depicted on this page are the main units of the set
and basic accessories, including the external hand generator and power unit.
Front panel, top and bottom chassis views of No. 18 Set transmitter and receiver
unit. Click on a picture to enlarge.
Under normal conditions the No. 18 Set was powered by a combined dry battery pack
known as "battle battery", which was carried inside the set.
Power Supply Unit No. 5 was a manpack equipment, providing HT, LT and GB for Wireless
Sets No. 18 and No. 68, and HT/LT for Wireless Set No. 38.
The whole unit was self-contained and built into a pressed steel case with carrying
harness, strap and web belt, similar to that used with the No. 18 and No. 68 Sets.
It incorporated a vibratory unit for HT and GB, driven from a 6V lead acid 14Ah accumulator
which was tapped at 4 volts for LT filament voltage. Whilst operating the set, the
accumulator was float charged by the hand cranked generator.
Two different output sockets were provided on the side panel of the Power Supply
Unit No. 5: for connecting Wireless Sets No. 18 and No. 68 marked '18' (top), and
for Wireless Set No. 38 marked '38' (below).
Power Supply Unit No. 6 was similar in shape and function, however, it was fitted
with a double voltage generator supplying 162V HT and filament LT voltage. A 2.4V
Nickel Iron accumulator was used to buffer the LT voltage. (Click a picture to enlarge)
When not required for use the accessories (shown above) for Wireless Set No. 18 were
packed in a canvas haversack (shown on top of the set pictured almost top right).
Click a picture to enlarge and for more details.