The AM Forum

I got my 5100-B going on all bands and I notice that the manual does not have a neutralization procedure.
I always like to do adjustments following the mfgrs reccommendations....so, before I start off on my own, does anyone have any more information on how B&W likes to do this?

Dave,

Because the feedback path for the neutralization cap goes through the band switched multiplier system, the perfect neutralization setting changes a bit from band to band.  I think this is the reason B&W skates around the issue a bit by stating that "the capacitor should be adjusted so that the final doesn't self-oscillate on ANY band".  On mine I found the best compromise setting was perfect neutralization on 15 meters (I adjusted so that minimum plate current was coincident with maximum output).  On the other hand if this turns into a single band rig then adjust it for that band.

If you slightly bend the mount for the neutralizing cap, it will point at an angle towards the side making it much easier to fit a screwdriver into the slot.

Thanks Rodger....
I bent the mount and it did make adjusting the cap easier.
The variable was somewhat non-responsive throughout it's range so I paralleled 10pf @ 6kv across it but it was too much. I didn't have anything smaller....so I removed the 10pf.
After playing around with removing the B+ at the base of the plate choke and removing the screen voltage at CH4 I was able to get it pretty close on 10mtrs but max power out was nowhere near the dip on 80mtrs.
I was able to select different tubes and found a set that will dip at max power out as well as peak the EXC indication all at the same time on all bands.

It's a squirrely buggar!