[AMRadio] WTB/WTS and a question


David McClafferty ve1adh at yahoo.ca
Fri Dec 30 17:12:53 EST 2005


--- Brian K Harris <brian.k.harris at philips.com> wrote:

> 
> The tubes all have 2V filaments.  The radio has two
> inputs for a filament 
> supply, 2V or 2.5V (the 2.5V input merely inserts a
> series resistor).  My 
> question is....why did anyone manufacture 2V
> filament tubes and what kind 
> of battery put out 2V or 2.5V?  I am building a
> solid state supply for the 
> 2V requirement as well so the question is merely to
> satisfy my curiosity.

A wet cell. You will have to have very good filtering
on the filament supply to avoid hum as the filament is
also the cathode.

Dave, VE1ADH

> 



	

	
		
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