[BC] AM HD power levels

[W2XJ]

I have always felt that way about 4-400s. An 833 equipped transmitter 
had tube life measured in years. A new 20V3 with 4-400s went 6 to 9 
months on a set of tubes. I have always felt that it was just false 
economy, especially when electricity was dirt cheap. I think the 
argument about fidelity is somewhat misleading.  The Iron in a plate mod 
transmitter is the primary thing that determines fidelity.

RichardBJohnson at comcast.net wrote:
> Calling some major segment of the broadcast transmitter
> industry dumb will not win an argument nor obtain any
> brownie-points.
> 
> The 833 rigs required about 170 watts of drive. In addition,
> the driver needed to be modulated. Furthermore, the
> modulator needed a low impedance driver (read high
> power) as well. The result was that the overall efficiency
> of the 833 rigs, Raytheon, RCA, and Gates, was about
> 40 percent. The newer designs using 4-400A and later
> 4-500A tubes had an overall efficiency of about 60
> percent. I was involved in the design of those rigs and the
> there were two criteria deemed most important:
> 
> (1) Fidelity.
> (2) Overall efficiency.