[Hallicrafters] SX-101A VS SX-115

[Jim Liles]

Hi Joe:
Thanks for the information -- always looking for unique stuff regarding the 
Hallicrafters line.  I've been in the sand box with a worthy number of 
Hallicrafters radio's and don't recall seeing anything but powdered cores. 
I've used coupled shorted turns to align the SX-24 and SX-25 but don't 
recall brass in follow on receivers or transceivers.  Please help me with 
the history of a few.  Kindest regards Jim K9AXN


->
> Message: 3
> Date: Tue, 14 Oct 2008 20:01:03 EDT
> From: WA1KBQ at aol.com
> Subject: Re: [Hallicrafters] SX-101A VS SX-115
> To: hallicrafters at mailman.qth.net
> Message-ID: <bf9.4a716e04.36268cbf at aol.com>
> Content-Type: text/plain; charset="US-ASCII"
>
> This is a very interesting subject and one that inspired and challenged
> Raymond S Moore several years ago. So which one really is the best? The 
> answer  to
> this question is elusive but can be found through exhaustive research,
> examining the engineering, mechanical construction and careful testing 
> which
> fortunately has already been done for you by Raymond S Moore several years 
> ago  and
> written up in his four editions of "Communications Receivers of the Vacuum
> Tube Era." After researching and testing hundreds of communications 
> receivers
> from nearly every conceivable commercial receiver manufacturer from 1932- 
> 1981
> Mr. Moore summed up years of work in his quest to find who actually 
> produced
> the  best receiver in a somewhat disappointing and frustrating: (drum roll
> please...)  "it depends."
>
> The Hallicrafters SX-88 gets my vote for best  all around classic BA band
> cruiser for general listening because it actually  performs better than 
> most in
> just about all areas of concern for equipment of  this type. The 
> mechanical
> construction is robust and the electrical design has  been fairly well 
> executed.
> I have restored four of these so far and I am always  amazed at how you 
> can
> put an SX-88 on an SSB signal right after a very short  warm up and it 
> won't
> budge. SX-88 was the first receiver to have an SSB function  marked on its 
> front
> panel and SX-88 has Litz wound 50KC IF transformers which is  the reason 
> for
> its superior performance. "Q" of the IF coils was over 180 due to 
> threaded
> ferrite slugs and ferrite sleeves. Notice SX-88 IF transformers do not 
> have
> threaded brass rod adjusters as do all other Hallicrafters.
>
> On  the subject of drifting... I have noticed some will be fairly stable 
> and
> some  will drift within a model line; tubes, NPO ceramic caps, who knows? 
> I
> have  encountered SX-101's that drift and have operated some that do not. 
> I have
> also  swapped tubes and noticed improvement. I had an  NC-400 on the bench 
> a
> while back that drifted so much it was a complete nuisance and I was
> surprised  to discover replacing the 0B2 voltage regulator fixed it. I 
> always enjoyed
> operating that one after getting it to work properly, I sure hated it 
> before.
>
> I think the answer is you have to decide what performance  features are
> important to you... for example, the SX-71 is popular, was  Hallicrafters 
> first
> dual conversion design and they actually worked fairly well  on 10 meters 
> but the
> pass band is only 5KC wide and you will wonder why you are  so tired of
> listening to it after a couple of hours.
>
>
> In a message  dated 10/14/2008 5:29:21 P.M. Atlantic Standard Time,
> k7mks at comcast.net  writes:
> Thanks to all for your comments; it is appreciated.
>
> Many tend  to favor the SX-115 with its newer design and less drifting.
> Several felt  the SX-101A would be the better AM receiver.
>
> When I posted my  question I had overlooked the 75A-4.  Guess the best way 
> is
> to give each of  the three a few weeks use, using different modes under
> various conditions, and  then decide.
>
> Thanks again.
>
> Joe  k7mks
>
>
>