[Amps] Plate Bypass Capacitor

[Manfred Mornhinweg]

Bill,

> However, your example of 600 VRMS on the plate of a 6146 grossly exceeds the
> manufacturer's ratings. RCA rates the 6146 at 400 VDC absolute max, which
> corresponds to a RMS max of about 280 V when properly tuned.

Not so...! I just checked datasheets for the 6146 (no suffix), for the 
6146A and the 6146B, from RCA and GE. They all agree on the plate 
voltages: 600V in CCS, and 750V in ICAS!

The 400V rating in the RCA 6146 datasheet is only valid for a special 
situation: Audio amplifiers which have the screen grid directly 
connected to the plate!

But now it's time for me to admit a mistake too: Somehow I was thinking 
that the 6146 series was rated for up to a kilovolt on the plate. That 
might be because in my young hotgun years I used to run them that way. 
With good cooling, and watching the plates, I got 160 to 180W PEP clean 
output in SSB from a pair of 6146B, ran from a power supply that gave 
950V at no load, and of course dropped some at full load. The tubes are 
still good today! That speaks of their quality. I didn't use a speech 
processor, though. Using one might have melted the tubes!

 > I realize your
> example was just for discussion but we might as well discuss real world. :-)

Yes, I agree! Let's stay real. So, let's settle on 500V rms on a 6146 
plate, to run it within specs in ICAS, OK?

Manfred.

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