[Amps] grounding grids

[k7fm]

The Heath SB-220 used an rf choke to ground the grid, bypassed by 3 x 200 pf 
capacitors.  Interestingly, the Drake L4 amplifier used an rf choke to 
ground the grid, bypassed by 3 x 200 pf capacitors.  That suggests that one 
manufacturer copied the other - or that both manufacturers copied someone 
else.

It has been stated that Bill Orr came up with the idea, so it is possible 
both companies figured it was magical and copied it without understanding 
it.  However,  my 22nd edition of the Radio Handbook (first printing 1981), 
edited by Bill Orr, has a 2 x 3-500 amplifier construction article and the 
grids are grounded directly.  If he was the one that suggested it, perhaps 
he was smarter by the time this edition was published.

This is a lucky engineer, when you design something wrong and it still works 
40 years later.

73,  Colin  K7FM