[Collins] 32 s 1 self oscilation

[Glen Zook]

Neutralization!  Follow the neutralization procedure in the 32S-1 manual.

Then, there are several things that can affect the neutralization:

Are you using 6146B/8298A or 6146W tubes or has the unit had those tubes in the final amplifier stage before?  If so, has your 32S-1 had the neutralization circuit modification?  If it has the modification then the neutralization capacitor inside the final amplifier cage will be an air variable.  If it is a ceramic trimmer then there is a VERY good chance that it will "burn up" using the 6146B/8298A or 6146W and oscillations will occur.

Are you mixing an earlier 6146 or 6146A/8298 with either a 6146B/8298A or 6146W.  Doing so will virtually always cause oscillations.

In addition, tighten EVERY machine screw and nut that goes through the chassis.  These do work loose and/or become corroded over the years.  They need to be checked and tightened every few years.
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: "drleborgne at aol.com" <drleborgne at aol.com>
To: collins at mailman.qth.net 
Sent: Friday, April 20, 2012 9:45 AM
Subject: [Collins] 32 s 1 self oscilation
 

Dear collins colleagues: My 32 s-1  seems to self oscilate  consuming transmitter power in the bands above 7.2 Mg.
Any suggestions where the problem might be ?  thanks  & 73 KI4JRY   Martin