[Johnson] Pacemaker

[Robert Nickels]

I'm again trying to convince myself I need to tear into the RF phasing 
network on my Pacemaker.   It has good suppression on some bands but 40 
meters is poor, and since the inductor has very little if any effect 
across it's entire range, it's clear that the components are not capable 
of producing the required 90 degree phase shift.   And since the 
inductor is unlikely to have changed value, that leave the capacitor, 
which I can see is a silver mica type, which makes it an unlike culprit 
as well.    The fact that EFJ's engineers chose to hide these parts 
behind a metal chassis that cannot be accessed without having to remove 
and re-string a dial cord really adds to the frustration.

I'm very familiar with the 9MHz type phasing exciters, and with the 
Heathkit SB-10 which like the Pacemaker, generates the phase-shifted LO 
on a different frequency for each band, but in my experience all are 
more stable than the Johnson method.   The AF phase shifter in the 
Pacemaker seems acceptable, the problems all seem to lie in the buried 
and inaccessible RF phase shift network, along with what I consider to 
be excessive drift in carrier balance.    So before I go there, I 
thought I'd ask to see if I'm missing something, or if anyone has any 
suggestions or words of advice.     I don't see any reason the Pacemaker 
shouldn't be able to generate SSB that meets the original specs with 
regard to opposite sideband and carrier suppression.

Thanks and 73,

Bob W9RAN