Opinions needed-SB-200 - Modifiy or not

[Brad Baker]

I've seen one mod for the SB-200, not sure if its a Harbach or other,
that you might consider avoiding. This one involved a change of the
grid bypass caps from 220 pf to a much higher value, resulting in
increased amplifier gain at 80m.

Its interesting that the grid circuit of the unmodified SB-200 is
similar to the Collins 30L1. The 30L1 uses a 220 pF to ground working
against 47 ohm (33 in the SB-200 I think). According to a Collins
engineer, this arrangement provides additional linearity for the
grounded grid amplifier by providing some negative feedback (via
plate-grid capacity?). He was surprised to see the Heath SB-200
incorporate this arrangement and claimed Warren Bruene, 30s1 designer,
came up with it.

Regards all,

--
--------------=/../=-----
Bradley Baker
n4ocb at kensho.2y.net

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