[AMRadio] DX-100B on Phone - bad audio distortion / oscillation

[manualman at juno.com]

Neutralization sounds like one used in the Heathkit Apache. I use 6146B's
in my Apache and the recommended band for doing neutralization is 10
meters.

Pete, wa2cwa

On Sat, 03 Dec 2011 17:34:21 -0500 Rick Poole <wa1rkt at arrl.net> writes:
> The SWR goes off the scale, which is a dead giveaway that the 
> transmitter is putting out RF on pretty much any frequency but the 
> one it's supposed to.
> 
>  >>>>>
> >  I'm thinking perhaps the finals are taking off on their
> >own, since they appear to be generating RF with no drive from the 
> 5763. If
> >so, you may need to add neutralization. But I can't explain why 
> this would
> >happen in AM and not CW.
> <<<<<
> 
> It's happening in CW now, too.  It happens reliably when I tune a 
> little off-resonance on the high side, i.e. the Plate pointer points 
> 
> to a higher number, and the plate tuning capacitor is more 
> meshed.  Maybe that's why I didn't notice it on CW before.
> 
> The PA has a neutralization modification whereby a wire is routed 
> from the driver capacitor to somewhere near one of the PA tubes, 
> then 
> you move that wire back and forth to find the sweet spot for 
> neutralization.  I have tried every position of that wire and 
> nothing works.
> 
> I've ordered some 6146A's to replace the 6146B's installed now, 
> since 
> some report problems with the 6146B's, and I know that some Collins 
> 
> KWM-2's, including mine, don't play well with -B's.  We'll see what 
> 
> happens when those arrive.
> 
> I'm just trying to figure out whether I should remove the 
> neutralization mod before installing the 6146A's.
> 
> Rick WA1RKT