[Boatanchors] 813s push pull Triode Connected Bias question.

[Jim Wiley]

Sounds about right.  The specs call for 490 watts audio output, but that 
assumes a "stiff" 2500 volts. You state that your circuit has 2500 volts 
at idle (no audio) but does not state what the HV is at max plate 
current.  If the HV were to droop as low as 2250 volts, then you can 
expect 380 watts of audio.  So, it would appear you are doing everything 
correctly. The spec sheet calls for 50 mA resting current, your 60 mA is 
within acceptable limits.

- Jim, KL7CC


On 4/22/2015 3:59 PM, Paul Baldock wrote:
> I just fired up my new  Modulator, driving a 10K resistor instead of 
> the PA. It works well except the efficiency is low. The HV is about 
> 2500V. Idle current is about 60mA (150W). Efficiency at 400W RMS 
> output is 42% as calculated by plate voltage times cathode current.
>
> Does this seem typical for this configuration?
>
> Thanks
>
> - Paul  KW7Y
>
>
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