Opinions needed-SB-200 - Modifiy or not

[Jeff Weinberg W8CQ]

Hi All,
Just a note that this modification is NOT a Harbach modification.

Regards,
Jeff Weinberg  W8CQ
Harbach Electronics
(317) 892-2641
http://www.harbachelectronics.com


----- Original Message -----
From: "Brad Baker" <n4ocb at KENSHO.2Y.NET>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Tuesday, September 18, 2001 8:07 PM
Subject: Re: Opinions needed-SB-200 - Modifiy or not


> 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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