>
>Dr. William J. Schmidt, II wrote:
>> <<** Ian -- For AB2, yes, but for AB1, control grid V-stability matters
not
>> since there is no grid current. >>
>>
>> Look. It does not matter if the tube draws grid current or not. If there
is
>> any signal impressed on the grid voltage via any means, it can lead to
>> distortion. Itís a simple concept. Regulation of the bias voltage is one
>> way, then, to ensure that it does not happen. The better regulated the bias
>> supply is (e.g. the lower the Z of the supply) the less likely this is to
>> happen. Here is a test: will the amplifier's unit impulse or step response
>> will be different with poorly regulated supplies?
>>
>>
>> Sincerely,
>>
>> Dr. William J. Schmidt, II K9HZ
>> Trustee of the North American QRO - Central Division Club - K9ZC
>
>
>I guess that is something that Collins Radio engineers did not know?
>They produced thousands of 32S1 and KWM2 radios with no regulated bias
>supplies.
>Lots of others too. Every SSB radio with 6146 finals in it that I can
>think of uses no regulated bias supply. Bias is fed by a large value
>resistor to the grids. bias voltage is free to swing as it pleases when
>the tubes are driven into grid current.
>10k to 20k resistor in series with the bias supply would hardly be a low
>Z supply.
>They are to be run in AB1 though.
>
amen, Gary
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