[Amps] 813 efficiency

[Paul Baldock]

I run a pair of 813's grid driven (grounded cathode). Plate voltage 
is about 2200V. I can get around 700W PEP on 15M and a little less on 
10M.  Because of the high output cap you need and L-PI. They run 
around 60% efficient.

- Paul  KW7Y

At 12:18 PM 2/20/2013, you wrote:
>Some time ago (maybe 2 years) there were comments filed on this site 
>regarding increasing the efficiency of the 813 tube on 21 - 28 
>mhz.  I've looked through my history of this group but failed to 
>find a reference.  I also checked some GE Ham News articles that 
>I've saved.  I realize the tube wasn't designed for this 
>spectrum.  However, I do seem to recall some references being made 
>on this site based upon personal experiences.  I really don't intend 
>to waste the groups time, but I sure would appreciate any circuit 
>suggestions that would lead to increased efficiency of this tube.
>
>73, Mike K4ELV
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