[Amps] Question re GU-74B grid current

[Vic K2VCO]

71% overall efficiency is remarkable for a class AB1 amplifier.

On 10/22/2012 12:10 PM, Val wrote:
> Jim,
>
> ACOM1000 and ACOM2000A are without doubt the most popular amplifiers based on GU74B. 
> Many thousands of them are working under the following conditions at1000W output:
> Plate  2350-2400V
> Screen 340V
> Anode current 510-580mA
> Bias between -45 and -65V for 220 mA idling current (the EBS keeps the bias between -65 
> and -75V for idling current of 70 mA when no RF drive)
> Normally the grid current is well below 10mA where the grid protection trips.
>
> 73, Val LZ1VB
>
>
>> Could somebody advise me as to the resting plate current and operating ctrl
>> grid bias voltage they are using on a GU-74B (plate voltage is 2500V, screen
>> grid 300V)? Also, does the tube draw grid current? I realize that in AB1, no
>> grid current should be drawn, but the tube characteristic curves predict
>> about 15mA grid current at full output (1000W output, 600mA anode current
>> (per tube) and 250W resting dissipation. I am interesting in what builders
>> are actually getting, and not information from data or spec sheets.
>>
>> Tnx and 73,
>>
>> Jim W8ZR
>>
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>
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-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/