[Heath] SB-200 - bias shift - solution

[Kenneth G. Gordon]

On 27 Sep 2011 at 19:04, Kenneth G. Gordon wrote:

> Well, the reason I get bias-voltage shift when I use the Harbach soft-
> key is that the power-MOSFET switch has as much as several ohms of
> resistance when it is "on". The same thing happens with the KeyAll.

Actually, I was wrong: it appears that the IRF9610 in my Harbach 
keyer is exhibiting an "on" resistance (Rdgs) of 189 ohms, instead of 
the 3 ohms it should be.

At 3 ohms, or even at the 6 ohms of the keyall, there should be very 
little bias shift. In any case, not enough to worry about.

I have ordered a new IRF9610 from Mouser.

Ken W7EKB