>2 wrote:
>
>> ** An early 2, 3-500Z circuit from Eimac's Bill Orr used chokes/caps on
>> the grids. Heath, Drake and Kenwood copied the idea. However, I have
>> yet to read an account of Bill Orr's reasoning behind the idea.
>
>Didn't the 30L1 do this as well?
** Good point, Vic. Yes. Maybe Bill Orr copied the idea from Collins
Radio? My take on Orr is that he was more of a merchandiser than an
innovator.
>Maybe they all copied Collins. As I
>understand it, the caps are series resonant with the grid lead inductance at
>some frequency, and -- at least at that frequency -- move the grid potential
>closer to ground, improving stability (again, only at one frequency).
** True, however, my guess is that the added XC only cancelled enough
811A grid lead XL to move the grid resonance up a few MHz. I tried using
smaller grid caps on a squirrelly SB-220. The 220's stability at 110MHz
seemed to improve only slightly so I began experimenting (1985) with
lowering the Q of the anode circuit 's 110MHz resonance.
>The chokes are there to provide a DC path, of course.
>
>73
>Vic K2VCO
>
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
end
|