A single wet cell (lead/acid) battery produced 2.2V. Bob Macklin K5MYJ Seattle, Wa.
----- Original Message ----- From: "Brian K Harris" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[email protected]> Sent: Friday, December 30, 2005 8:21 AM Subject: [AMRadio] WTB/WTS and a question > 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 >
