[Hallicrafters] SX-101A VS SX-115

[WA1KBQ at aol.com]

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


______________________________________________________________
 
**************New MapQuest Local shows what's happening at your destination.  
Dining, Movies, Events, News & more. Try it out 
(http://local.mapquest.com/?ncid=emlcntnew00000002)