[Hallicrafters] Best RX?

Tom Rousseau tomr at gorge.net
Sat Nov 27 22:11:33 EST 2010 

Greg,

Yes, that is the same James McLaughlin.

He published an article in QST, June 1941 describing the selectable sideband
system, and followed it up with another article in October 1947 giving
improvements and more detail.

The key characteristic of the McLaughlin approach to sideband selection is
to take advantage of a selectable higher or lower heterodyne frequency in
converting to the 50 KC IF.  Properly adjusted, this system has the
advantage that both the upper and lower sideband positions have exactly the
same frequency response characteristics:  when you change sidebands, they
sound exactly the same.

This is different than most other filter systems, which usually change the
carrier oscillator (or BFO), or sometimes select a different filter relative
to a single carrier frequency.  In either case, the tonal qualities are
slightly different because the filters are usually asymmetrical.

Hallicrafters used the McLaughlin system of sideband selection in their
popular receivers having a 50 KC last IF from the SX-96 through the SX-117.
Prior to the SX-96, they probably hadn't figured out the advantages of this
system (S-76 and SX-88, which require adjusting the BFO from one filter
skirt to the other).  After the SX-117, the SX-122 went back to the BFO
adjusting approach, probably to save a little cost.  The SX-122 is a cheap
version of the SX-100.

Hallicrafters also used the McLaughlin system in the HT-30 transmitter.

Interesting to look at this history.

Tom  K7PJT

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of WA1KBQ at aol.com
Sent: Saturday, November 27, 2010 4:14 PM
To: hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] Best RX?

Good post Tom,
 
The McLaughlin side band selection scheme you mentioned, I wonder if this  
is Jim McLaughlin who worked with James Lamb in the mid-thirties to develop 
the  XE1G Dual Diversity receiver which Hallicrafters made soon afterwards 
as the  DD-1 with chief engineer Karl Miles and Jim McLaughlin consulting?
 
Regards, Greg
 
 
In a message dated 11/27/2010 6:49:30 P.M. Eastern Standard Time,  
tomr at gorge.net writes:

The  SX-111 may look similar to a SX-110, but that's where the  similarity
ends.

As already pointed out, the SX-110 comes from the  S-20R, S-40, S-85, SX-99
lineage.  It is single conversion with a 455  KC IF.

The SX-111 is architecturally very similar to the SX-101, being  primarily a
cost reduced version.  Both are double conversion with a  1650 KC first IF,
50 KC second IF, same McLaughlin sideband selection  scheme and a similar
tube line up.  The SX-111 saved money primarily  by eliminating a lot of
expensive mechanical material (cast escutcheon,  heavy duty chassis and
cabinet, robust tuning capacitor, geared tuning,  fancy
selected-band-backlighting, etc).  Compare the block  diagrams.

The SX-101 takes its general architecture from the SX-100,  primarily being
converted to ham band only, optimized for ham performance,  and beefed up
mechanically.  But comparing the block diagram, they are  very similar.  The
SX-100 evolved from the SX-96 which evolved from  the S-76 (the first
Hallicrafters to employ their popular 50 KC last IF  scheme for 
selectivity).

The SX-115 is pretty much a new architecture,  except it borrowed the 50 KC
IF from the SX-101, et al, and the VFO from  the HT-32/37.  The SX-117 is
quite similar to the SX-115  architecturally, though cost reduced in many
ways.  Nice little radio,  though, for its intended purpose.

My favorite of this lot is the  SX-115, followed by the SX-101, for ham band
only.  The SX-100  certainly has its warts, but for a general coverage
receiver it is very  nicely balanced, giving good overall performance in a
compact package at a  good price.

Tom  K7PJT

-----Original Message-----
From:  hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net]  On Behalf Of Carl
Sent: Saturday, November 27, 2010 2:45 PM
To:  rbethman; hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] Best  RX?

The SX-111 is a hamband SX-110 which is a SX-99 and on back to the  SX-9.

You already have my SX-101 opinion but you havent said what you  intend to 
use any of them for?

Carl
KM1H


-----  Original Message ----- 
From: "rbethman"  <rbethman at comcast.net>
To:  <hallicrafters at mailman.qth.net>
Sent: Saturday, November 27, 2010  3:54 PM
Subject: Re: [Hallicrafters] Best RX?


>
> What  ever happened to the ORIGINAL question/post?
>
> Somehow it got  painted over and/or buried.
>
> Bob Macklin has size, space, and $  limitations.  He "presented" the
> choices and was asking about the  SX-101 and the SX-111.
>
> Bob - N0DGN
>> ----- Original  Message -----
>> From: "Bob  Macklin"<macklinbob at msn.com>
>> To:  "Halicrafters"<Hallicrafters at mailman.qth.net>
>> Sent:  Saturday, November 27, 2010  11:23 AM
>> Subject:  [Hallicrafters] Best RX?
>>
>>
>>> What  was  Hallicrafters best overall receiver?
>>>
>>>  I am familiar with the  SX-28 and SX-100. I have a SX-110 which leaves 
 a
>>> lot to be desired. A  SX-110 is just a SX-99 with a  sliderule dial.
>>>
>>> I'm interested  in  knowing about the SX-101 and SX-111.
>>>
>>> Bob  Macklin
>>>   K5MYJ
>>> Seattle,  Wa.
>>> "Real Radios Glow In The Dark"
>
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