On Thu, 11 Sep 97 03:29:34 -0800, Rich Measures <measures@vc.net>
wrote:
>>On Wed, 10 Sep 1997 19:06:30 -0500, w5ec@digitalexp.com (Hawkins,
>>Bill) wrote:
>>
>>...snip... ... Had I kept it, I would have cut
>>a hole in the side of the cabinet and mounted a fan just for the tank
>>coils.
>>
>Sounds like a good idea, Bill. Heath did it right when they blew
>cooling air over the tank in the SB-220 - despite the subsequent
>blatherings of naysayers.
>
>>I now have a homebrew 8877 and an Alpha 91B with the optional fan,
>>either of which will run brick-on-the-key at 1500 watts out,
>>guaranteed.
>>
>Does the 91 have an inductance in series with the grid termination R? If
>so, how much L? What is the value of the GTR?
>thanks
>Rich---
>
_______________________________________________________________
No coil in series with the grid terminating resistor. From the
grid(s), there is a 1 mHy coil to the bias supply, a pair of .02 mF
caps in parallel to the GTR, and from them, the GTR directly to
ground. The GTR is 50 ohms, 90 watts. The cathodes each have a 12
ohm 5 watt resistor directly to ground, with nothing else. The
cathodes are not connected to the heaters. Each tube has its own
anode suppressor, each one is a pair of 220 ohm, 2 watt resistors in
parallel with a coil of unknown inductance. There are no other
suppressors such as ferrite beads, etc, visible on the schematic.
73, Bill W7TI
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