I still dont understand the claim made by a few that increasing gain and
power output increases stability when hard grounding the grids.
I would take various web sites with a grain of salt and try to seperate the
good from bad.
The 115pf caps were chosen by Heath at the end of the SB-220 run and a
bulletin suggested changing them. The SB-221 and HL-2200 use the 115pf but
Ive replaced with whatever 110 and 120pf I come across in bulk. Ive yet to
have instability in a well built and updated SB-220, even on 6M, with the
Heath design.
Carl
KM1H
----- Original Message -----
From: "Jim W7RY" <w7ry@centurytel.net>
To: "Randall K Martin" <rkmassoc@comcast.net>; <amps@contesting.com>
Sent: Sunday, June 02, 2013 4:38 PM
Subject: Re: [Amps] Source of Mica Caps?
Ground the grids directly and remove the caps and chokes. BUT install a
glitch resistor in series with the B+ and a diode from chassis ground to
B- (anode to ground, cathode to B-). W8Ji's web site has lots of
information on this.
73
Jim W7RY
-----Original Message-----
From: Randall K Martin
Sent: Saturday, June 01, 2013 5:39 PM
To: amps@contesting.com
Subject: [Amps] Source of Mica Caps?
Does anybody know where I can buy a replacement for one of the mica grid
bypass capacitors used in the Heathkit SB220? I believe they are 115 pf.
Can't find anything close in the mouser catalog.
73
Randy K0EU
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