[Amps] Fw: True dissipation rating of GU-74B/4CX800A?

[w9gt@comcast.net]

----- Original Message ----- 
From: w9gt@comcast.net 
To: amps-request@contesting.com 
Sent: Monday, June 03, 2002 12:33 PM
Subject: True dissipation rating of GU-74B/4CX800A?


Hello amps enthusiasts,

I am preparing to assemble a home brew amp project using Russian ceramic GU-74B/4CX800A tubes.  I sure would appreciate some experienced input regarding the dissipation ratings of these tubes in the HF range up to 30 MHz.  Why do many of the Eastern European and Russian vendors (and some data sheets) for surplus tubes describe them as rated for only 600 watts?  The Svetlana data sheet, however, describes them as being capable of 800 watts.  Is there a difference between newly manufactured tubes and the commonly available military surplus variety other than the markings and brand name?  Or, perhaps are these military ratings vs. commercial or amateur ratings?

It seems that these tubes ,if in fact they are analogous to 4CX800As, should be capable of 800 watts of anode dissipation.

It is also interesting to note that one U.S. manufacturer of amplifiers claims to get over 2500 watts output out of a pair of these tubes.  I wonder if they are using the surplus variety or newly manufactured versions?  All of this is leading to a simple question:  Would it be a good idea to run two, or three tubes in a full legal limit amplifier (1500 watts PEP out) and expect reasonably long tube life and good performance over all bands?  Of course, in consideration of good engineering practice, cost vs. benefits, and reasonable efficiency.

Thanks for your input!

73,  Jack, W9GT


--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
---