>Peter Chadwick:
>>... ... ...
>>>I would be very inclined to measure the IMD with W8JI's 3 tone test,
>>>with 2 of the tones about 40 or 50 Hz apart - that will show up any
>>>problems with the time constants in the SG circuit as well as in the HV
>>>PSU.
>
>Rich Measures:
>
>>The G2DAF circuit's screen voltage remains constant during such tests.
>>However, with voice modulation, the screen voltage - and the IMD -
>>fluctuate wildly.
>
>* This is not true. The screen voltage will most certainly fluctuate, as
>thats the general idea with the circuit. However, that does not mean that IMD
>also * "fluctuates wildly"!
Eimac says that fluctuating screen voltage increases distortion. I'd say
that a total IMD of roughly -22db below PEP seems pretty wild to this
non-expert. .
- Perhaps the reason that screen voltage needs to be regulated is
because of the exponential relationship between screen volts and peak
anode amperes. .Add some grid current, and it's downtown
Distortionville.
Rich...
R. L. Measures, 805-386-3734, AG6K
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