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
