|[AMRadio] WTB/WTS and a question|
Edward B Richards
zuu6k at juno.com
Fri Dec 30 12:09:20 EST 2005
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
> 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
> using three 45V batteries in series for the 135V B+, it used four
> 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
> 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
> 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
> 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
> By the way, this set uses a pair of push-pull 49's for the audio
> stage. These are zero bias tubes in Class B with 3.5W capability.
> Thanks for reading,
> Brian WA5UEK
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