[Amps] R. MEASURES PRAYERS ANSWERED

[Vic K2VCO]

R L Measures wrote:

> Shorting the cathode-grid tuned-input of a g-g amplifier shorts the VHF 
> feedback path that supports parasites.

They are talking about a grid-driven amplifier with link-coupled input 
and output.  I think their idea is that the VHF grid circuit is formed 
by the inductance of the grid tuning capacitor's frame and stray 
capacity to ground.  As far as VHF is concerned, the grid tank coil is 
already shorted by the low reactance of the grid tuning capacitor, so 
putting a jumper across it won't affect the VHF behavior much.

> With the feedback path shorted, the amplifier is sure to be stable.  As 
> I see it, this procedure is some dude's fable.

They've shorted the HF tuned circuit in the grid, but not the VHF one.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco