Are 813's suitable for HF SSB?

[Meir WF2U]

Any tube, if operated within the specifications (bias, dissipation  
etc.) is capable of/suitable to be used as a linear amplifier, whether  
it's for audio or HF SSB (provided it also specified for the desired  
operating frequency).
There are more modern tubes which are specifically designed for  
producing less IMD (intermod in brief) products at maximum rated power  
output in the class of operation normally associated with SSB linear  
service (AB1). As long as the power is withing the tube design  
parameters, and the amp is not overdriven, the the IMD is really not a  
problem, even with older, tubes before the SSB era.
Tubes are designed "optimized" for SSB service only because some  
commercial requirements for certain IMD parameters.
The 813 makes a nice, relatively inexpensive linear amplifier. In fact  
I have a 2 x 813 homebrew linear amplifier covering from 20M through  
10M someone built from the GE tube application notes. Puts out 500W   
but it'll load with no strain to 600W PEP output on SSB.
The 1 KW PEP you're referring to is input power, which is about right  
for AB1 operation efficiency.
Whoever is claiming that the 813 is not suitable for linear amplifier  
service, doesn't know what they're talking about.
BTW for many years I made my living designing high power linear tube  
amplifiers for LF, HF and VHF...

73, Meir WF2U
Landrum, SC

Quoting kd4e <doc at KD4E.COM>:

> I am reading totally divergent opinions online about the potential for dual
> 813's on HF for 1KW PEP (SSB).
>
> On one hand there are amps with dual 813's producing only 400W PEP and
> other sites claim 1KW 160-10M.
>
> I am also reading that 813's may be unsuitable for SSB but fine for AM-CW,
>
> "Although a pair of 813s was perfect for legal limit operation on CW and AM,
> the tube was unable to supply the high peak inputs permitted in single
> sideband
> operation, and thus the popularity of the tube dropped as SSB became
> the preferred
> mode over AM." then other Hams say that they are wonderful G-G amps with
> excellent SSB performance.
>
> Here are three samples of sites promoting the 813:
> http://www.wb8erj.com/813input.htm
> http://www.angelfire.com/tx5/wieser/813amp.htm
> http://members.westnet.com.au/page3/two_813_grounded_grid_RF_amplifier.htm
>
> I had been looking at a GS-35B, GU-43B, or dual GI-7B design for the small
> size and solid performance.
>
> WDYT?
>
> -- 
>
> Thanks! & 73, doc, KD4E
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