[Amps] Question re GU-74B grid current

[Carl]

Thats being rather polite about it (-;

Carl
KM1H



> 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/
>
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