In the reference book Wireless for the Warrior Volume 2, 36 different patterns of British and Commonwealth hand microphone are listed, used with a wide range of different radio sets and in different configurations for different climatic conditions. In the past we have looked at examples of the No 3 and No 16 hand microphones, but today we are looking at another variation, this time the No 4 microphone:
This shares the same basic design as the others, however this one is designed for use with the Nos 8, 12, 21 and 33 set radios. The designation of the microphone, plus its ZA5313 stores code is moulded into the plastic on the front of the microphone:
In order to use the microphone, the button on the side needs to be depressed:
The microphone connects to the wireless itself using a four point plug:
As mentioned above, with 36 distinct variations of microphone, there are plenty to track down, but I must confess finding it very hard to get really excited about tracking them all down! I will pick up cheap examples that come across my path but I am in no rush to get the set!
Tales from the Supply Depot 
The No.4 was initially used with the WS18 as well (following the replacement of the WS8), but was later replaced by the 4A which had stranded wire in the cable for the LT supply to the valve filaments. (The microphone switch also controlled the valve heater supply to the transmitter and receiver sections, and the original ‘tinsel flex’ (copper foil wound on thread for extra flexibility) was rather high resistance and cause too much voltage drop (and effectively shorter battery life) as the set battery ran down with use.) The switch on the hand microphone also had to be used to control the set when wearing a respirator with a microphone fitted. The No.16 microphone is simply a ‘tropicalised’ version of the 4A, with plastic coated instead of fabric covered cable, the connector filled with wax for waterproofing, and a sealed microphone insert.