The HQ-170 was the packaging of the HQ-110 and the HC-10. The HQ-110 was a
rather ordinary, but small and compact, amateur band only receiver. The
HC-10 is a nice if adapter that converts the normal 455 kHz if to a much
lower frequency, then adds a product detector. The HC-10 is highly sought
after. Selectivity can be quite narrow, and it has a product detector,
which a number of other old boatanchors do not have.

The main limitations of the HQ-170 would be stability and frequency readout
on 10 and 15 meters. Since the high frequency oscillator is close to the
ham band, drift is more of a problem than with the receivers that have a
crystal controlled front end. But, on 80 or 40 or 160, who cares.
Stability is ok there.

IF bandwidth is wide enough for good am, but some audio engineer came up
with the bizarre idea to vary the fidelity of the audio output depending
upon the avc voltage. It was called "Auto-Response" and assured distortion
when there was qsb. The fact that they promoted it rather than hiding it
never did make sense.

My neighbor had one and worked a hundred countries on sideband with it and
probably 50 countries on 6 meters am, so it was good enough.

Each of these old receivers has their qualities and quirks - which makes
them almost human.

73, Colin K7FM

COLIN LAMB wrote:
snip
IF bandwidth is wide enough for good am, but some audio engineer came up
with the bizarre idea to vary the fidelity of the audio output depending
upon the avc voltage. It was called "Auto-Response" and assured distortion
when there was qsb. The fact that they promoted it rather than hiding it
never did make sense.

Hi,

The audio feedback percentage is not dependent on the AVC voltage,
but on the setting of the audio gain pot. If you leave the audio
gain at a low setting, you get more negative feedback,
hence a smoother audio response. The feedback is via resistor
R80 (100 Ohms) at the audio output transformer secondary,
to R77 (47 Ohms) between the bottom of the 1 Meg audio gain pot
and ground.

My HQ-170 audio sounded a lot better with the cardboard back removed
from the matching Hammarlund speaker housing.

My HQ-170 responded very well to an alignment, although it is more
drifty than I like. I picked up a small filament transformer
for the VFO and mixer tube continuous filament voltage mod,
but haven't quite gotten around to installing it yet.
(Can it be 5 years, now?)

73,
Ed Knobloch

Hi Chuck:

Well, that was from memory. You are right it is an audio feedback based
upon the gain control. The Drake 2B had negative feedback audio and sounded
better.

The last one I worked on, someone had run 100 watts into the antenna input
and that required manufacturing new coils. The forms were ruined. It would
not have been so bad, but when the radio quit, he switched bands to find out
why - with the transmitter still on.

73, Colin K7FM

And, that was Ed, rather than Chuck. I sometimes get confused after
midnight and before 11:59 pm

K7FM