[ARC5] OT: Hally Instability.

[Richard Knoppow]

    Hallicrafters strong point was good value.  Their sets mostly 
delivered good performance at an affordable price but they didn't make 
much world-class stuff.  There is a propaganda film called "Voice of 
Victory" available at you tube and at www.archive.org that is mainly 
about production of the BC-610.  What is interesting is how much change 
the Signal Corps required to make it suitable for mobile military use. 
Nearly all was undoing cost cutting in the original design.
    There is also a WW-2 vintage Signal Corps communications manual(I 
don't remember the number) which shows spurious response charts for 
several SC receivers; the Super Pro has only a single image while the 
SX-28 looks like a corn field. OTOH, the SX-28 was a little more than 
half the price of the Super-Pro and had all sorts of features that would 
make the owner feel as though he/she had the latest technology even 
though it didn't work that well.

On 11/15/2015 10:18 AM, Todd, KA1KAQ wrote:
> 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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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL