[Hammarlund] HQ-180A Mixer Trimmer mods.

[Cecil Acuff]

Al,

        The info you are looking for is in the 1988 Proceedings publication. 
Likely your receiver was modified by Steve Bohac of New Jersey.  What you 
describe sounds like a black panel where the clock used to be...that now 
contains the AC power switch and a Mixer Trimmer control.  It is described 
in Proceedings as a varactor circuitry that peaks the receivers mixer 
circuitry at any point in the tuning range.  It compensates for the small 
amount of mistracking of the main tuning variable capacitor.  It works much 
like an antenna trimmer except it works in the mixer.  It is suppose to 
allow a 3 to 4 "S" unit improvement in receive level.  It works with a small 
circuit board that is mounted under the chassis.  Other mods Steve was known 
to do were BNC antenna connector on rear panel and solid state power supply 
mods....which I think some of the 180's had from Hammarlund if I remember 
right.

That's about all the info I have on it...

Sounds like a nice radio!

Cecil Acuff...
----- Original Message ----- 
From: "Albert Santangelo" <ve3ajm at sympatico.ca>
To: <hammarlund at mailman.qth.net>
Sent: Monday, November 08, 2004 7:28 AM
Subject: [Hammarlund] HQ-180A Mixer Trimmer mods.


> Just recently acquired a nice HQ-180A.
>
> A "Mixer Trimmer" potentiometer and new mounting plate is positioned on
> the front panel where the clock would be. And there is a small circuit
> board mounted underneath the chassis with some components, including
> what looks like a varactor diode.
> Its all been done very well, and the mixer pot seems to add a few S
> units to a signal, and acts similar to the Antenna trimmer control.
>
> Is anyone on the list familiar with these mods, or a schematic of the
> circuits. I seem to remember a SWL publication that mentioned something
> about this mod. in the past. Thanks very much.
>
> Al Santangelo VE3 AJM
>
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