[Hammarlund] HQ-180 IF Alignment and L-4

[Byron Tatum]

Hello-
    I have a question regarding the IF alignment of an HQ-180:
        In looking at the 60 KC IF response charts in manual you can see that at 
the "USB" and "0.5 KC" switch positions the IF response pattern is very centered 
and symmetrical about 60.0 KC. So, I assume that is why they have you align the 
60 KC IF in those positions.
        My question is the adjustment of L-4, the 395 KC osc tuned circuit. The 
Vernier Tuning control on front panel moves this osc plus/minus 3 KC. Of course, 
the Vernier Tuning control is set in middle at zero and L-4 is peaked for max 
response when a 3035.0 KC signal is fed into the second converter while the IF 
switches are still at USB and 0.5 KC.
        After carefully performing this alignment, including zeroing the 
BFO, with very accurate signal generator frequencies I notice that 
when switching from USB to LSB there is a dramatic difference in pitch and 
background noise strength. By adjusting the Vernier Tuning control this can be 
altered and reversed. I assume this is why in the manual they say to use the 
Vernier Tuning control for max intelligability when tuning SSB.
        What I did was to tweak L-4 a little so that I get the same response in 
either USB or LSB with BFO and Vernier Tuning both at zero. I checked my 
single-signal response and it appears by ear just as good as before. This way, 
sidebands can be switched and received with the same pitch without having 
to move the Vernier Tuning or BFO front panel controls. Can anyone find any 
fault with this? 
                                            Thanks, Byron WA5THJ