[Hammarlund] HQ-110 alignment

[Julian Bunn]

Thanks to Ken for his comments on my web page describing IF sweeps.

Some clarifications on my setup: I do in fact use the sweep generator's 
ramp output as the
X input on the scope, and it is this ramp that I run at 1ms. I.e. the 
sweep generator runs between
400kHz and 500kHz in 1ms. I probably need to make that clearer on the 
web page. (I use
the 10second sweep temporqarily while visually checking that the 
frequency limits are where
I want them.)

There are two types of display that are produced, and I haven't quite 
understood why yet.
If you look at this picture: 
http://pcbunn.cacr.caltech.edu/jjb/hammarlund/if-fg504-4-1.jpg
you will see the standard IF bell curve on the 7904. This is what 
appears when the Y plates are connected
at the input to the demodulator tube i.e. pin 2 of V7, the output from 
the T5 IF can,
and is what I believe you see in your setup.

However, when the Y plates are connected to prior IF stages, the IF 
response curve looks like
this: http://pcbunn.cacr.caltech.edu/jjb/hammarlund/sweep2.jpg

In the former case, the signal appears to be demodulated/rectified. In 
the latter it is not. That's my
theory, anyway (I am by no means an expert in any of this).

Julian