14-07-2011, 08:25 PM
In good deed for the day mode yesterday I picked up a couple of big old radios from a chap near Durham on my way down to Nuneaton for another chap from Rugby. When I collected the radios, Paul showed me some of his vast collection, including a 2 valve '20s set. This had some unusual controls including a swich to turn off one of the valves (apparently to extend battery life) and a control for valve filament current. I wondered if anyone here knows the purpose of this latter adjustment? Is it another means of extending battery life by just putting a resistance in series with the heaters?
