Wireless of the Week - week 24

[Bruce Parker (RIP)]

Along with the No.11 set, The Wireless set No.9 was ubiquitous in the early war years. It was originally designed as a tank radio to which, given its size, I can only conclude the set’s designers never actually looked at the tiny Vickers and cruiser tanks in service at the time. As such, it was more typically used as a vehicle radio in wireless trucks or as a ground station.

The Wireless set No.9 was developed in the mid 1930s to replace the unsuccessful tank sets then in use. It was used throughout the early war years and was very reliable, though suffering from limited frequency range. Difficult to mass produce, British production ceased after 4000 sets were built. Canadian production continued until 1942 with an estimated number of less than 500 sets. Interestingly, the Canadians further developed the No.9 set into the No.9 Mk.1 in 1943, which itself was further developed into the very successful Wireless Set No.52 of 1944.

The No. 9 set featured here is a Canadian one manufactured in 1942. The receiver and power supply unit are Canadian Marconi Company products with wrinkle green finish and the sender was built by Northern Electric Company Limited with a gloss black face. I have seen a total of three Canadian No.9 sets and all of them were mismatched like this which may indicate Marconi got the contact for parts of the set, Northern Electric the rest, and the two companies never worked out a common finish.

The set consisted of a receiver on the left, a rotary transformer power unit in the centre and a sender on the right. The three units were held in an aluminum shock mounted carrier that had plugs to connect the units along its top back. Complete, it was 41” wide by 16” tall by 12” deep and weighed 192 lbs. It operated R/T (voice), CW and MCW (morse) and its AM frequency coverage was 1.875 to 5 MHz with a range of 10 miles (voice) up to 35 miles (CW) using a standard 6’ aerial. Different aerials could be used to increase range and these could be located some distance away from the set when an ‘Aerial Coupling Equipment B’ was used. Volt and ammeters were plug in so they could be easily replaced and access to the sender valves was through doors on the set’s face. The set could be tuned to and switched between two channels, A and B, coloured coded red and blue so the operator could keep track of them. Like the No.11 set, switching between ‘send’ and ‘receive’ was accomplished by manually moving a large plastic knob on the supply unit. Power to the set was 12 volts typically provided by pairs of 6 volt lead acid batteries.