[Heathkit] Tube subs in the HW-101

[Kenneth G. Gordon]

FYI, the 6AH6 is a much higher-gain and more stable version of the 
6AU6. However, although installing a set of those in the IF amp (V-3 
and V-4) of the HW-101 will result in higher power output for the 
transmitter, doing the sub badly upsets the AGC circuit. The "S" meter 
will read S-9 on signals that would ordinarily be about S-4 or less.

Another tube to watch out for is the 12AT7 which is used as the 
heterodyne oscillator and buffer. If this tube is weak or bad, overall 
signal level for both transmitting and receiving will be way down.

Setting the heterodyne oscillator test point voltage to exactly 2 V, will 
make the "S" meter readings more "common" from band to band.

In fact, you can just about set the heterodyne oscillator adjustment 
peaks at the proper places by tuning to the center of each band, turning 
on and tuning to the calibrator signal, peaking the preselector, then 
adjusting the heterodyne oscillator slugs for maximum "S" meter 
reading concurrent with stability. (I use this method to eliminate from 
consideration this problem that might be causing low transmitter 
output.) I peak the "S" meter reading, then back the slug off 1/2 "S" unit 
on the SLOW side.

Ken W7EKB