On May 31, 2006, at 6:37 PM, Vic K2VCO wrote:
> R L Measures wrote:
>> Does this involve keying the amplifier with zero drive, and tuning
>> the Tune-C and Load-C throughout their ranges?
> [think of a grid-driven amplifier with link-coupled input and output]
> Short the grid tank coil so that there's no possibility of tgtp
> oscillation at operating frequency.
Shorting the cathode-grid tuned-input of a g-g amplifier shorts the
VHF feedback path that supports parasites.
> Replace fixed bias with grid leak of 10-20K. Disconnect any load
> from output. Reduce plate/screen v so dissipation rating isn't
> exceeded. Adjust grid tuning capacitor in steps from max to min;
> at each step, tune plate capacitor through full range. Any flicker
> of grid current or dip or flicker in plate current indicates
> oscillation. If found, use absorbtion wavemeter to determine
With the feedback path shorted, the amplifier is sure to be stable.
As I see it, this procedure is some dude's fable.
> Vic, K2VCO
> Fresno CA
R L MEASURES, AG6K. 805-386-3734
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