[ARC5] OT: Hally Instability

[D C _Mac_ Macdonald]

I'd say that the stability is mostly related to the quality of the components. My first commercial receiver was a well-used National NC-33. It was replaced by a Halli S-20R which was much more sensitive on 20 and up.  I was using AM then with a Globe Scout and Heath VF-1 VFO (later replaced by WRL 755 VFO). With the latter VFO, I'd zero-beat SSB QSOs at the high end of 75 meters and join in.  It all stayed stable enough that the SSBers usually didn't realize I was on DSB AM unless they tuned off frequency a bit.  I didn't notice any bad instability on the S-20R or the S-40A replacement on 75 meters.  Warmup drift, but I usually left my receivers turned on 24/7. 
 
I'm pretty sure the right angle was just a packaging decision.  The ARC-5, etc. capacitors are physically very large and solid compared to consumer stuff.
 
* * * * * * * * * * * 
* 73 - Mac, K2GKK/5 * 
* (Since 30 Nov 53) * 
* k2gkk hotmail com * 
* Oklahoma City, OK * 
* USAF & FAA (Ret.) * 
* * * * * * * * * * * 
 

 
> From: releazer at earthlink.net
> To: arc5 at mailman.qth.net
> Date: Sun, 15 Nov 2015 18:08:22 -0500
> Subject: [ARC5] OT: Hally Instability
> 
> When I started researching ham band receivers in 1974 I noted a magazine review of the NC-270 that mentioned the 1/8 thick steel front panel - and said you could tune in a signal, raise the front of the radio a inch or so, let it fall, and still have the signal tuned in. That was one reason I bought a National NC-155, a "Chevy" version of the "Cadillac" NC-270.
> 
> But I have noticed something about military receivers that have excellent stability, such as the 274-N and ARC-5 series as well as the BC-348 and I would guess the BC-342, too..  The tuning cap is not turned directly by the knob on the front panel but instead through a 90 degree turn.
> 
> Is this 90 degree turn a feature designed help stability or just a consequence of the packaging and the need for a proper gear ratio?
> 
> Wayne    
>      
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