[ARC5] OT: Hally Instability.

[Todd, KA1KAQ]

I don't think there's any big mystery involved, Dave. Hallicrafters
produced a lot of models, primarily for the 'entertainment'/consumer
market. The better the model, the better the performance. Aging of
components would play a role in any receiver, of course. Age of design is
another consideration. The early Hammarlund Super Pros  for
example(pre-war) were some of the finest receivers of their time, yet
suffered from the usual issues above 20mcs on the SX models. They also
suffered from drift until warmed up, but the manual makes it pretty clear
that they were meant to be turned on and left on. The SPs got a bad rap
later for drift issues related to folks not heeding this advice, along with
the well-used examples that hit the surplus market and got used without any
repair or replacement of aged components.

You're right about the SX-101 - both that I owned drifted like crazy. They
added a resistor aka damp chaser to keep a couple critical components
'pre-warmed' in an effort to deal with some of the drift, so later 101
models performed better. My SX-28A drifts, mainly because it's never been
gone through. Stopped using it until it gets a good re-cap and resistor
check. Someday....

Halli did make a few decent sets like the SX-73 and SX-115. But they were
pricey. The SX-88 is probably one of the most over-rated receivers out
there, swooned over by collectors due to low production numbers (it was a
dog as far as sales go) far more than actual performance. By the 60s they
seem to have figured it out but their halcyon days were behind them.

The long and short of it is, you got what you paid for. The cheaper the
set, the more marginal the performance. And now of course, older technology
and components don't have the performance of later designs. If you use your
Halli primarily for listening to AM, drift is less of an issue. Far more
noticeable on CW/SSB signals. I think it was Collins who was first to
conquer the drift issue with their ground breaking PTO design.

~ Todd,  KA1KAQ/4

BTW, the SX-42 was the post-war upgrade of the SX-28 if I remember
correctly. SX-62 shared a similar design, without bandspread.

On Sat, Nov 14, 2015 at 10:26 AM, David Stinson <arc5 at ix.netcom.com> wrote:

> I'm not doubting anyone who says their Hallys were stable.
> I do know in 40+ years of hamming, I've handled dozens
> of them and never seen a single one from the "ham" market line that didn't
> show mechanical instablilty and "wibble-wobbles" above about 12 MC.
> Is it possible this was some sort of aging-related
> design flaw that a few were spared?
> Has anyone ever done a through investigation
> to find the root of it?  Coils mounted on a long
> bandswitch that will transmit shocks like a tuning fork always seemed a
> candidate to me.
> Most likely there are multiple causes.
>
> 73 D.S.
>
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