[Boatanchors] Reducing filament voltage

[David Knepper]

I am finishing the wiring on my Collins 4A (circa. 1934) transmitter.

The problem is to produce 2.5 volts for the 47 volt oscillator tube.  The 
newer transformer that I am using has a 6.3 volt winding.  Someone told me 
about using a couple of 1N4007 in series from the filament lead to the pin 
socket.

I am sure that somone will tell me to use a series resistor or use a later 
tube with a 6 volt filament.  What tube might that be to replace the 47 
tube?

Any ideas?

Thank you
David Knepper, W3CRA/W3ST
Editor of the Collins Journal
Secretary of the Collins Radio Association
www.collinsra.com
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