[ARC5] OT: Hally Instability - Hammarlund drift.

[Dennis Monticelli]

Glen,

I had a used HQ-170C while in high school.  I used the clock to turn on the
radio one hour before I arrived home from school for exactly the reason
stated.  It was a nifty trick.  Now if only I could have shut up that
humming clock :-)

I had forgotten about that bit of trivia, Glen.  Thanks for reminding me.

Dennis AE6C

On Thu, Nov 19, 2015 at 6:39 AM, Glen Zook via ARC5 <arc5 at mailman.qth.net>
wrote:

> In the late 1950s, early 1960s, some of the Hammarlund advertisements for
> receivers like the HQ-170, HQ-110, etc., mentioned using the clock / timer
> to turn on the receiver for like 1-hour before it was to be used.  This was
> to improve stability. Glen, K9STH
> Website: http://k9sth.net
>
>
> Here you go, gents:
>
> http://amfone.net/Amforum/index.php?topic=15703.0
>
> Ralph/W3GL posted this on AMfone.net some years back after we had discussed
> the early Super Pros in a Tech section thread. I think Ralph is 89 now and
> used these receivers in WWII.
>
> Be sure to read down further as someone else included info on another
> change of that time that involves adjustment of the variable cap for
> additional warm up drift improvement.
>
> You're right on the money, Ken. I need to look through my manuals again to
> find the actual quote from Hammarlund about leaving the sets on for
> extended periods to stabilize. Few folks ever really understood much less
> appreciated the process of thermal stabilization.
>
> Probably most noticeable is the lack of drift or frequency jump from
> bumping the panel, thumping the desk, etc. Mechanical stability is top
> notch, for its day and well beyond.
>
> ~ Todd/KAQ
>
> BTW, I've heard from some folks who claimed the addendum changes made no
> big improvement. Upon questioning, it seems they hadn't gone through and
> changed out bad caps, checked for out-of-tolerance resistors, done an
> alignment, or even checked tubes in one case. These changes were intended
> for a well-performing receiver, not a tired, old carcass limping along on
> its original 75 yr old components.
>
>
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