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 <[EMAIL PROTECTED]> 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 > > ______________________________________________________________ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:[email protected] > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb > >
