Quote:
Originally Posted by Philliphastings
Hi Mike,
I now have several from around the country - some with four 807s and some with the more efficient 2 output valve modification.
I’m still trying to find a WS No19 Mk3 which I believe is the correct set to match with the Amplifier RF No2
Cheers
Phill
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The 4-valve version was extremely inefficient and overheated rapidly on long transmissions. Modifications were made, including the addition of an air intake and filter (I have no idea where the air was supposed to go afterwards, unless they punched holes in the outer case underneath the mounting plates.)
The Mk.3 was the final 2-valve version, and was usable with the WS19 Mk.2 and Mk.3 (there's a note about "specially selected sets" in order to get enough drive at the upper end of the frequency range).
Control leads exist in multiple variants (one of which is NOT for the amplifier).
6-pin to 6 pin with 2-pin socket on flying lead. (WS19 Mk.2 original)
6-pin to 12 pin with 2-pin socket on flying lead. (WS19 Mk.2 with later PSU)
12-pin to 12 pin with 2-pin socket on flying lead. (WS19 Mk.3)
The 2-pin socket is wired in series with the HT2 feed and connects to the control relay coil. Cable lengths for the leads vary, depending on the set installation and carrier used - the White scout car had the set and amplifier mounted side by side so has a very long cable on the 2-pin socket.
The 'other' cable (not for the RF Amplifier) has the 2-pin socket connected across the Valve Heaters and Relay supply (i.e. chassis and +12V) and was used in 24 volt 2-wire AFVs to provide power to the WS38AFV (and also the later WS88AFV) by using the rotary transformer to split the 24 supply into 0-12-24 in a stable fashion. If you plug one of those into the RF Amplifier it will go to continuous transmit!
(The RF Amplifier No.1 was an entirely different beast, and used to turn the WS12 into the WS12HP - which eventually developed into the WS53.)
I have a No.2 with [12V] on the ID plate, implying there was a 24 volt version, but have never seen one except in old copies of Wireless World advertisements from P.C.A. Radio in Shepherds Bush (London). If there were any made I suspect they were for export or trials only: the rotary converter is a great deal smaller and similar to the fully shrouded aircraft types of the 1950s.
(P.C.A. Radio was set up by the Polish Comrades Association after WW2 to make electronic equipment for military use. Mainly ex-Signals people. I think it went through a few name changes and was eventually bought by Colomor Electronics (the Giacomelli family who are still around, selling surplus kit on eBay).
Best regards,
Chris.