My latest addition - Radialva Groom

[Robert Darwent]

Hi John,

Looking at your prototype back cover got me thinking and I went on an internet search of suitable images to use as a guide to make a reproduction cover myself in due course.

However, I stumbled upon something interesting at the same time - I've found at least four different back covers used on the set!

Cover 1

   

specifying valves 6E8G, 6K7, 6Q7, 25L6, 26Z6 and 7V/0.1A dial bulbs. This is the variant I have.

Cover 2

   

specifying valves 6E8G, 6K7, 6H8, 25L6, 25Z6 and 7V/0.1A dial bulbs. This is the variant you have John, so the 6H8 and associated circuit differences are original and not a later modification by a previous owner.

Cover 3

   

specifying valves ECH3, EF9, EF9, CBL6, CY2 and 7V/0.1A dial bulbs. This is the same valve line-up as used by the later Braun F56GW clone.

Cover 4

   

specifying the same valves as 'Cover 1' but with 4V/0.1A dial bulbs, obviously it must be fitted with a different value shunt resistance across the two bulbs to compensate.

I have only been able to find a single circuit diagram for the set though, which refers to the variant using 'Cover 1'.

Regards