cutting: Teledyne

I have a model of this, and downloaded schematic. It shows 90vdc, 221/2 vdc but it also shows A & B voltages. I'm not the smart'its cookkey in the box but, what voltage are these. This is the oldest radio i have every had and worked on. In fact the tube bases I have never seen before.Please if you can help It sure would help. Thanks. Milt

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In the really old days they had low value wire wound resistors (0.1 to 1000 Ohms) and also Grid leak resistors (1M to 4M ohms approx).

Intermediate values either impossible or very expensive. So since the HT  battery pack (US B+) is made of  1.5V cells (60 to 80), or even earlier a tray of 2V batteries (45 to 60) the simple solution for the lower HT voltages on a screen grid or RF anode is a tap off the battery.

So when Dry cells replaced Wet for HT (B+)  packs like the Winner and Vidor L5038 equivalent used. The GB suffix on a "Winner" means the Radio 0V goes to a 6V, 7.5 or 9V tap and the "C" (GB = Grid Bais) battery is thus in the HT pack rather than a separate battery. 

You can check to see if the 22.5V is Positive  for Screen Grid (g2)  or actually a "C" battery (usually 9V though) and thus negative.

The A or "LT" is for the filaments. Prior to 1938 usually 2V, 4V or 6V Wet Lead Acid (or gel pack on portables). Really old sets may have 3V or 5V filaments off 4V or 6V battery via rheostats.

Later models in late 1930s used series resistors from a single HT for Screen Grids and RF anodes etc and a single series resistor between HT- of B battery and 0V to develop a -5.6V bias for the output valve (Thus 560 Ohms for a 10mA HT). Thus later HT packs are like the Vidor L5039. The LT whould be 2V Lead Acid by 1938. Though the 1.4V "All Dry" Octal came out in 1938/1939 and RCA subminiature B7G in 1939/1940, in the UK some 2V LT sets made up to 1950 due to War Time induced shortages. See Earliest UK B7G / Miniature valve Radios

Some late 1920s and up to mid 1930s models may use up to a 136V HT and perhaps three other voltage taps to various Screen Grids and HT end of Anode coils AND a separate 9V GB (C supply) with FIVE taps.  Not forgetting 2V, 4V or 6V Lead Acid LT ("A" supply). Accumulator GZ

There are exact US equivalents of course of UK batteries listed.

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