Fullerphone Mk IV (Canadian)

Fullerphone Mk IV (Canadian)
	; Fullerphone Mk IV* (Canadian)
Specifications
Weight	14 lb (6.4 kg)
Length	12 in (30 cm)
Width	7 in (18 cm)
Height	6 7⁄8 in (17.4625 cm)

The Fullerphone Mk IV (Canadian) is a Second World War era portable telegraph instrument designed for field use and so isn't truly a telephone. The Canadian version differed only in details from the British version.

Between 1941 and 1943 Canada produced 14,000 Mk IV and Mk IV* Fullerphones. The Morse key fitted in the earlier production instruments had a Canadian Key W.T. 8 Amp No. C2 while later produced Canadian Fullerphones were fitted with a Canadian Key W.T. 8 Amp No. C3 which was a simplified version with two U-shaped bridges of pressed steel construction.^[1]

Normal operating range was 15 to 20 miles however, as a direct current instrument where operation could be achieved with as little as 0.5 microampere flowing, range was only limited by resistance in the line and stray earth currents.^[2]