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833A




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From:  SBJohnston-at-aol-dot-com [SMTP:SBJohnston-at-aol-dot-com]
Sent:  Thursday, February 26, 1998 1:21 PM
To:  tesla-at-pupman-dot-com
Subject:  Re:  833A


Greg wrote:

>I lucked up on an 833A triode (for free!).  
>I have no experience with the big tube.  

By some standards, it is not a "big" tube <grin>:  it's typically a 500 watt
tube in continuous (CCS) broadcast audio or RF service.   I have always liked
them and even built a custom transmitter around four of them.   They normally
run a nice orange-red color at full power.    

The original RCA 833 was a strong tube with a very heavy plate structure.
 The story goes that they just ran and ran and wouldn't fail, so of course
RCA had to redesign a replacement for them, the 833A, with a lighter-weight
sheet metal plate that had a shorter life - repeat sales, you know!  I hear
that one of the Chinese tube companies is making the 833 to the original
specs.

I looked in the RCA transmitting tube book and here are some  detailed specs
for your application: 

Filament:  10 volts ac or dc, 10 amps.
Plate dissipation w/natural cooling:   350 watts
Plate dissipation w/forced  cooling:  450 watts

Class C amp or oscillator RF service, intermittant-duty (ICAS), w/forced air
cooling:

DC Plate voltage:  4000 vdc max.
DC Plate current:  500 ma max.
DC grid voltage:  -500 vdc max.
DC grid current:  100 ma max.
Plate input:  2000 watts max.
Plate dissipation:  450 watts max.

>Is it OK to mount it horizontally?  

Yes - it says so in the book, but I have not seen them mounted that way in
any commercial application.  And I just noticed a week ago that the ones I
had in the garage have suffered filament collapse from vibration while
sitting on their sides <damn!>.   I think would mount it vertically.

If you'd like I can scan the RCA book pages for you and send it to you
directly as an email attachment - let me know the graphic format you prefer:
 TIFF or GIF (or something else).  

Steve Johnston

sbjohnston-at-aol-dot-com