On Thu, 9 Jul 2009 13:16:38 -0700, "Richard Knoppow"
wrote:


"tchrme" wrote in message
...
A question for those with Hammarlund experience,
I have just restored my first HQ rcvr and the manual
says I need a
sweep generator and a scope to align the IF. On most of my
other rcvrs
(Hallicrafters), I just use a signal gen and a VTVM. Is
this really
necessary or can I just peak the IF's? Mike KF6KXG

The HQ 129X and its earlier versions use over coupled
transformers in at least one position. While these can be
just peaked the tuning will not be right although the set
will work. A sweep generator and scope will allow proper
tuning. The overall IF curve is supposed to be relatively
flat topped and have good skirts neither of which will be
obtained by simple peaking. I haven't looked at the tuning
instructions but it may be possible to determine the right
frequencies to peak the individual coils in the IF
transformers and use a very accurate source to peak them.
That's no trick now since the frequency counters in some
multimeters are quite accurate enough.
I also suggest that a good signal generator with known
frequencies will be helpful in adjusting the RF sections.
The frequency calibration of the main dial should be
reasonably accurate and RF tracking good. This was a deluxe
receiver in its day. However, it has only one RF stage so it
will have images on the higher bands. Hammarlund chose to
use three IF stages to obtain better selectivity and leave
the RF with a single stage. A combination of both two RF
stages and three IF stages is found in the Hammarlund
Super-Pro, perhaps the best communication receiver built
during its lifetime.

I have an Hammarlund HQ-145 which in some ways is a lineal
decendent of the HQ 129X (which I also once had) and the
HQ-140 which was described at the time as a miniature tube version of
the 129. The manual I have for the 145 states that the sweep
generator and an O'scope are ideal for alignment, but lacking those
a VTVM and a signal generator will work as well if not "as well as."

I haven't tried either method with my HQ-145. I just did the peaking
thing when I had an HQ-129X some 40 years ago and it seemed to
work just fine though I had nothing to compare it with.

Jon W3JT