Heathkit SB-400 Neutralization Procedure

[Stu Lyon]

Wayne,
There is a way to neutralize by adjusting for a plate current dip that
coincides with max power output but that method is very inexact. The best
way is to disconnect the screen and plate voltages and adjust for a null
output. If you have access to a high frequency scope (>50 MHz), that's the
best null indicator.

A good place to disconnect the plate is at the high voltage filter
capacitors rather than bending back the feed-through capacitor lead in the
final compartment. As I recall, it's a blue wire.

Please head Glen Zook's advice and replace with 6146s or 6146As. NOT 6146B
or W -- these tend to be unstable at 15 meters.


73, Stu W6CUX
Winnetka, CA
s.d.lyon at earthlink.net

----- Original Message -----
From: "Wayne Mackin" <wmackin at ROGERS.COM>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Tuesday, December 02, 2003 6:23 AM
Subject: Heathkit SB-400 Neutralization Procedure


> I'm about to replace the 6146 finals in my SB-400, and was wondering if
> there is a procedure for neutralizing the transmitter that does not
require
> disassembly of the unit and unsoldering of components? (the only procedure
> in the manual is done before final assembly of the TX).  Seems to me that
> there must be a way to adjust (or check the adjustment of) the
> neutralization capacitor with the rig operating normally - or am I wrong?
>
> Your suggestions are appreciated!
>
> Regards,
>
> Wayne
>

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