[Collins] 6EA8 sub'd for 6U8 in KWM2

[Dr. Gerald N. Johnson]

On Sun, 2007-08-19 at 14:20 -0400, john wrote:
> Just noted that in the KWM2 I"m working on, V12 and V13 have been replaced 
> by a 6EA8.
> 
> Was this a popular swap....what was the intent?
> 
> Thanks
> John K5MO
> 
Within the last month that's been asked and then I could find no
significant tube manual differences to say 6EA8 or 6U8 was better. I do
know that 75S-1/2 use 6U8 and by the time of the 75S-3B/C those
receivers used only 6EA8.

Carl's and Glenn's comments on longevity could be a good argument for
the 6EA8.

Manual dated 1978 that is on line says SB-10 cures an audio oscillator
VHF parasitic oscillation. It seems to hook a 47 ohm resistor between
the tube screen pin and the bypass capacitor. Other early mods made in
production fairly early by the number check on values in the twin T null
network that determines the frequency and also suggest the plate
resistor won't cook so fast if it has a 1 watt rating instead of 1/2
watt.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer