[Collins] Looking for information on the Cunningham C201 and C203 tubes

[Dr. Gerald N. Johnson]

Some sources I have didn't help. This one might be wrong.

ARRL 1943 Handbook shows a 203A and a 303A in triode transmitting tubes. 
100 watt plate dissipation, 130 watts out Class C telegraphy. 10 volts 
3.25 amps filament. Exactly like a type 211 (VT-4C used in BC-375) 
except the amplification factor (mu) is 25 in the 203A and 12 in the 
211. So the 203A needs -125 volts bias where the 211 needs -225. The 
203A runs 25 ma grid current and the 211 runs 18 ma. Same plate voltage, 
drive power, and output power. If this refers to a Cunningham number it 
might be good data, if not, its noise.

There might not have been an RCA equivalent ever. At least one web page 
hints the 300 series Collins rigs use Cunningham tubes to avoid paying 
Sarnoff for the privilege of buying RCA tubes. On at least a couple 
other known documented occasions Collins used unusual tubes to avoid 
paying patent royalties.

I do have some older Radio Handbooks, not ARRL, but they haven't 
appeared on my new bookshelves yet, but I'm unboxing other magazines 
from the same area of old shelves and they might appear someday.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association

On 9/1/2010 1:44 PM, John Hensley wrote:
>
> Some early Collins transmitters (1930's) used Cunningham tubes.  One unit I have been studying used C201 or C203 tubes which I am wildly guessing weretriodes.  Dunno.
> Can anyone show me a diagram with operating voltages, etc. for these andwhat would have been more modern substitutions?  A pair of the C201 ran100W I believe as compared with the C203 which could do 250 watts.
> All I know.  Any input appreciated.  The Cunningham #10 catalog does notshow them.  The bottom line is I need to figure out the closest RCA equivalentwhich might be available.
> Thank you,
> John W5JV 		 	   		
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>