[AMRadio] WTB/WTS and a question


KB2WIG at twcny.rr.com KB2WIG at twcny.rr.com
Fri Dec 30 12:37:19 EST 2005


from the'63 RCA Tub Man....2A3 power triode,plate 200v,3.5W  mue 60,  
2A5,twin diode/high mue triode,, 2A7 Pentagrid converter---- more 
stuff, diodes, etc... then there are the 3V stuff.....  the Manuel is 
gud reading on long winter nights......   klc
----- Original Message -----
From: Edward B Richards <zuu6k at juno.com>
Date: Friday, December 30, 2005 12:09 pm
Subject: Re: [AMRadio] WTB/WTS and a question

> Hi Brian;
> 
> In my ignorance, I have never heard of 2 volt tubes. What are their
> numbers? Thanks and HNY.
> 
> 73, Ed Richards K6UUZ
> Simi Valley, Ca 93065
> Home of the Air Force 1 pavilion
> 
> On Fri, 30 Dec 2005 10:21:15 -0600 Brian K Harris
> <brian.k.harris at philips.com> writes:
> > Good Morning,
> > 
> > 1.  I would like to buy or swap for two solid state plug-in 
> > replacements 
> > for the 872A mercury vapor rectifiers for my KW-1.  Enuf said.
> > 
> > 2.  I am restoring a broadcast/shortwave radio set for my 
> brother.  
> > It is 
> > an RCA 8BT, battery operated 'farm set' from the 30's.  In 
> addition 
> > to 
> > using three 45V batteries in series for the 135V B+, it used 
> four 
> > small 
> > 1.5V cells for biasing the 1st detector and the 1st and 2nd 
> IF's, 
> > and a 
> > multi-tapped battery to get 3V bias for the 2nd detector and 
> 7.5V 
> > bias for 
> > the audio driver.  As my brother doesn't live on an electricity 
> > deprived 
> > farm, I am building a solid state AC supply to meet those needs.
> > 
> > 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.
> > 
> > By the way, this set uses a pair of push-pull 49's for the audio 
> > output 
> > stage.  These are zero bias tubes in Class B with 3.5W 
> capability.  
> > Very 
> > cool.
> > 
> > Thanks for reading,
> > 
> > Brian WA5UEK
> > 
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