I want to second a previous post which asked about loading. Is your amp
fully
loaded?, because Ig is somewhat high and plate current has what I guess is a
one tube value at full output.
Best regards
Guillermo - LU8EYW.
Scott Townley escribió:
> Numbers according to Eimac in parentheses:
>
>
> Measured power out: 855 watts (1200)
> Power input: 1216 Watts (1980)
> Ep:3200 Volts (3000)
> Ip: 380 Ma.( at max output) (660)
> Ig: 250 Ma. (200)
> Eg: Bias 00 (0)
> Static Ip: 120 Ma. (140)
>
> PS that would all be with 80 watts drive.
>
> Not an expert, but sounds like the plate impedance is too high. That would
> give low Ip and high Ig. According to the datasheet it should be ~2500
> ohms for two in parallel.
> Really the question is, what's the screen current? I would think that even
> in g-g/triode-connected service the screen current is a key indicator.
>
> I don't recall the exact bits but the 850A isn't tapped correctly as-is
> from the factory. Obviously it will resonate with the right tune-C but the
> Q is way off from what you normally shoot for.
>
>
>
> At 07:27 2005-10-11, Bruce Lanning wrote:
>
>>Several years ago, I built a GG amplifier using a pair of 4-400A. The grid
>>and screen are grounded at the tube socket.
>>
>>I feel that the power out is quite low. Below are some of the operating
>>parameters:
>> Measured power out: 855 watts
>> Power input: 1216 Watts
>> Ep:3200 Volts
>> Ip: 380 Ma.( at max output)
>> Ig: 250 Ma.
>> Eg: Bias 00
>> Static Ip: 120 Ma.
>>
>>I am using the B&W Pi-network, model 850A output tuning inductor
>>.
>>I have checked the tube filament pins for a poor solder joint.
>>They both looked OK, but I resoldered them to no avail.
>>
>>Maybe someone out there could throw some light on my problem, or if I even
>>have a problem...
>>
>>
>>
>>
>>
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>
>
>
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