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Author Topic: Hallicrafters SX-42 vs SX-43  (Read 3933 times)
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AB3FL
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« on: September 13, 2012, 09:45:15 AM »

I am looking to buying a SX-42 or SX-43.  Now I know that the SX-42 has PP audio and uses a ratio detector as opposed to a limiter-discriminator.  I am interesting in using it for a receiver with my valiant and for general AM/FM listening.  I can find the SX-43 for around $100.  The SX-42 however is usually a lot more.  What are the other differences such as selectivity and sensitivity.

thanks

Tom - AB3FL

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N8ETQ
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« Reply #1 on: September 13, 2012, 10:53:59 AM »

Hey Tom,


From:http://www.ohio.edu/people/postr/bapix/sx43.htm



SX-43 compared with SX-42
The SX-43 is a lower cost (and easier-to-lift) version of the SX-42 with 11 tubes compared to 15 in the SX-42. Introduced in 1947, a year after the SX-42, the SX-43 uses a ratio detector in place of the SX-42's limiter-discriminator and single-ended audio in place of push-pull audio. It also eliminates the voltage regulator and has a number of changes in tube complement for otherwise similar functions. Like the SX-42, the SX-43 is a general coverage receiver for AM, CW and FM. The SX-43 has a gap in coverage from 55 to 86 MHz which the SX-42 covers fully.



   Perhaps the recession right after WWII made sale of
high end stuff difficult.

73

/Dan
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WQ9E
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« Reply #2 on: September 13, 2012, 01:21:56 PM »

The single RF stage of the SX-43 will result in lower image rejection at the higher end of the shortwave range if that is of interest to you.  Selectivity choices are more limited with the SX-43 but the four selections (two with crystal filter and two without) will cover your needs.  But I find I use all three bandwidths of the non-crystal selectivity of the SX-42 regularly.

I have both and have restored a couple of both and one of the most noticeable differences is you give up the very nice tuning feel of the SX-42 with the lower cost SX-43.  If you plan to use it for CW you will appreciate the greater mechanical stability of the SX-42 compared to its light weight younger brother. 

The SX-43 is a competent receiver and will play just fine for AM use and is OK for CW.   But if you were looking for a SX-42 and you settle for a SX-43 you will probably soon become dissatisfied with the 43.  The SX-42 is one of my favorites, to me the SX-43 is "just another receiver" and is nothing special outside of its FM broadcast coverage which few other communications receivers offered.
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Rodger WQ9E
AB3FL
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« Reply #3 on: September 13, 2012, 01:55:57 PM »

How good does the SX-43 sound on the FM broadcast band as compared to the SX-42?

Tom - AB3FL
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WQ9E
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« Reply #4 on: September 13, 2012, 02:34:45 PM »

Tom,

In my opinion there isn't much difference when comparing FM as long as you use a good/efficient speaker with the SX-43.  The 42 clearly has more audio power capability but the bandwidth on either is fine for FM broadcast and the ratio detector works fine.  I have never measured the sensitivity but the 43 works fine in my rural location with a very small antenna-the nearest broadcast stations are 25-45 air miles away.

 I believe RCA developed the ratio detector as a way around Armstrong's patent on the limiter discriminator setup and the ratio detector became the standard for consumer radios until more modern methods (like PLL) displaced it.  Unlike the discriminator detector, the ratio detector has sufficient AM immunity for broadcast listening without the need for prior limiter stages.  The more complex multiple limiter followed by discriminator was used in the commercial (not broadcast) services of the day where it could provide better results on weak signals.

The radio quality of either the 42 or 43 probably exceeds the source quality provided by most broadcasters these days.

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Rodger WQ9E
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« Reply #5 on: September 13, 2012, 03:12:35 PM »

The lack of SX-43's on the market compared to their competition or even the SX-42 says it all. It was a dog from the beginning.

If all you want is general listening plus FM the SX-62A may be a better choice. Its a SX-42 without bandspread and IMO, a much nicer dial. OTOH both are not a beginners radio to do a full overhaul on, and both will quickly reward you with fried power and audio transformers and burnt bandswitch and tone control wafers if not done.

Carl
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N8ETQ
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« Reply #6 on: September 13, 2012, 11:09:59 PM »

Yo'

   Right on Carl, I loved my 62... Sweet piece!!


The lack of SX-43's on the market compared to their competition or even the SX-42 says it all. It was a dog from the beginning.

If all you want is general listening plus FM the SX-62A may be a better choice.
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Todd, KA1KAQ
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« Reply #7 on: September 14, 2012, 11:13:36 AM »

I've always thought of them in terms of previous models, the SX-43 being more like a pimped up S-40 or Sky Buddy and the SX-42 being the updated SX-28.

As Carl points out, the SX-62* is basically the entertainment/consumer version of the SX-42, which is more or a communications/amateur model. Love my -62B, it has an incredible dial face as well as great audio.

SX-42s, like most other equipment, have come way down in price over the last few years. They are a bit annoying to service as is the -62, but it's no contest for me. Given the choice, I'd go for the -42 hands down.
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« Reply #8 on: September 14, 2012, 11:18:58 AM »

I use 2 of the 62A's. One in the LR driving a 50's RCA console PP 6V6 amp section and 4 speakers, it has a wider range of tone and loudness adjustments.

The other is in the BR driving a R-42 at much lower volume Smiley

The SX-42 is in the basement paired with the matching HT-9 but its nowhere near a good AM battle conditions radio so it is seldom used on the lower bands.
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Todd, KA1KAQ
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« Reply #9 on: September 14, 2012, 11:24:49 AM »

Yep, mine occupied the Family Room/Parlor in the old house up north. Visitors always noticed it since it sat across the room alone on a small table. Had it lashed to an old Dukane school speaker which would rattle the walls when cranked up. It's about to see the light of day again, might have to set it up in the living room here. Space is the only issue.
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« Reply #10 on: September 14, 2012, 05:39:39 PM »

SX62 is a cool SWL radio.  I have mine in the room off the kitchen.  I used to play FM jazz through it sometimes as background music. Now the our Jazz station is well, not jazz anymore.   I would sell it I guess.  I would hate to ship it.  It is a very very nice example.

I love history and when I toured Airforce one, I saw the SX62 installed into the presidential chair.  They said JFK would sit and listen to it with headphones on for hours as they flew.  There was a long wire on top of the plane for the radio.

I like my SX42 alot.  Its one of my favorites.  I have recapped the rig.  ALL of the caps.  The radio never worked correctly and after weeks of work and another week from an elmer, I found the problem.  The factory hooked the bypass caps to the wrong side of the coils on the RF section.  I clipped them out and soldered new ones on the right side of the coil.  After an alignment, the radio is better then ever.   Several people off the hallicrafters group have thanked me for posting that.  It seems it was not just my radio that was built that way.

I do not like, the S meter system.  I love watching the s meter as I am listening to the rig.  This one is the backwards type.  You can have the signal read correctly, Or you can have it zero but you cant have both.  

C


* SX62-presidential.jpg (190.18 KB, 1037x778 - viewed 254 times.)

* front side.JPG (458.5 KB, 1549x1037 - viewed 158 times.)
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AB3FL
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« Reply #11 on: September 15, 2012, 03:24:29 PM »

I plan to use it to listen to broadcast and pair it with my valiant for ragchew.  I think the SX-43 would probably do what I need.  However the SX-42 would be better.

Tom - AB3FL
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« Reply #12 on: September 15, 2012, 09:19:00 PM »

Quote
I've always thought of them in terms of previous models, the SX-43 being more like a pimped up S-40 or Sky Buddy and the SX-42 being the updated SX-28.


The SX-43 has a crystal filter so its more of an updated SX-24 and followed by the SX-99 which was a much better seller but no FM....that was a short lasting experiment.
If you want a low cost radio to go with the Valiant get a HQ-129X or 140X. They are more selective and have a better crystal filter. 

I sure wouldnt call the 42 an updated (as in improved) SX-28 in many areas.

Carl
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AB3FL
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« Reply #13 on: September 15, 2012, 09:37:30 PM »

I am really looking for something with FM.  I am going to the GCARC Ham fester tomorrow, maybe I will find a SX-42 there.  Maybe I will just wait until I can find a SX-42 for the right price


Tom - AB3FL
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« Reply #14 on: September 15, 2012, 10:37:06 PM »

Tom,

Good luck at the hamfest tomorrow and I hope you find some interesting stuff.

Is your operating position big enough to fit two receivers with the Valiant?  The SX-42 is better than the SX-43 and the SX-62 is a fun receiver (I have a couple) but the tuning rate is too fast for practical operation on the ham bands.  A SX-62A was my station receiver for my first week as a novice in 1975 and I was very happy to replace it with a SX-101.

If you have room for a pair of receivers, consider picking up a nice SX-62 for FM and general AM/Shortwave broadcast use and then something that also has the capability to really perform under tough conditions.  The SX-42 is nice but when the going gets tough a later receiver with sharper selectivity and selectable sideband on AM will often make the difference between enjoyable operation and only copying a small part of the other station's transmission.   My personal favorite for a Valiant mating receiver is one of the ham band only SX-101 series (be careful because the latest iteration substitutes a "converter" band in lieu of 160 meter coverage) or a Hammarlund HQ-170.  Both do a good job of letting you instantly select whichever sideband has the least QRM on AM.  Other Hallicrafters receivers with this capability include the earlier SX-96 and SX-100 which are general coverage and the later SX-115 and SX-117.  The SX-111 is a slightly cost reduced version of the SX-101 but retains its selectable sideband feature in a lighter weight package with a less sophisticated tuning drive.  There are some nice offerings from National also like the HRO-50 (-1 version has better selectivity), HRO-60, and NC-183 (D) but I often miss the selectable sideband feature with these.  I do have a HRO-60 paired with one of my Valiants and it is a good receiver and I do like it a lot for CW.

In any case, hopefully tomorrow will yield some good receivers.
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Rodger WQ9E
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« Reply #15 on: September 16, 2012, 12:38:54 PM »

Thats sound advice rodger but the SX101 is way to tight for Hifi AM.  Listening to round table copy at 5 to 6KC is nauseating.   

How do I sound?  You all sound the same on this SX101!

I have the version with 160 and I do like it.  I compared it to 75A4 on 20 meter SSB and was pleasantly suprised at the 101's performance.

I just thumbed through the SX42 manual and it seems that with the IF and Xtal selectivity you can go from about 20kc down to 5KC.  Then, You have the tone control to further tune. 

The HRO 50-1 and the HRO60 are in the same boat.  To tight for hifi AM.   The HRO 50 is sweet and goes 20+ wide for those clear band nights. 

If its the king of the big HiFi sound you want, I think the 42 or 28 is the way to go. If thats not of concern, Rodger was spot on!

I think alot of the choice of buying a boat anchor is "love at first sight".  I saw an SX42 with the R42 speaker and it was over at that instant. I had to have it.
C
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« Reply #16 on: September 16, 2012, 03:27:38 PM »

A properly aligned SX-101 series provides equivalent bandpass on AM with a traditional receiver with a 10 Khz. IF filter because you are choosing only one sideband instead of centering the signal in IF pass band.  Most stations shouldn't have much audio response out above 5 Khz. unless Tiny Tim is at the mic Smiley

The SX-101 family, like the similar vintage Heathkit RX-1 and Hammarlund HQ-170/180,  require very careful alignment with their low frequency final IF (50 to 60 Khz. depending upon model and manufacturer) because the audio does get ugly otherwise.    Most hams probably don't own signal generators that go this low.  Tuning is also critical and I strongly suggest that once you are sure your receiver is properly aligned, including accurately set BFO, tune in AM for zero beat with the BFO on and then shut if off.  This assures that the receiver is tuned to the proper frequency.  Heathkit felt the need to send out a letter to early RX-1 owners who complained about poor audio response on AM while using the RX-1.  With SSB they had to tune correctly because otherwise you got nothing but "monkey chatter" but on AM the demodulator does work with the signal centered but with resulting very poor frequency response.

I regularly use my SX-88 for the regional AM net on Saturday morning, generally set for 5 Kc bandpass, and stations with good audio sound good and the only stations who sound better in the 10 Kc position are those who are considerably off frequency.  A couple of stations using "weird" equalization sound different in the 10 Kc position but it would be a major stretch to say they sound better.  Under tough conditions I do use the 2.5 Kc position but fidelity is obviously compromised at that point.  The biggest drawback with the SX-88 compared to the later family members (SX-96 and on) is that it doesn't provide switch selectable choice of sideband on AM so you have to re-tune (when interference appears on the opposite side) so that the carrier sits just inside the desired side of the IF bandpass.  
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Rodger WQ9E
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« Reply #17 on: October 04, 2012, 09:45:08 PM »

OK....I am looking at the SX-62A.  I know it does not have a band-spread or a Guess Meter.  Is the tuning good enough for say normal AM ragchew on 75M?  I do have a digital readout from N3ZI.  I am not interested in CW or SSB as I have a Kenwood transceiver for that.


thanks

Tom - AB3FL
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« Reply #18 on: October 04, 2012, 09:57:48 PM »

Tom,

The SX-62A should do fine for AM on 75 meters.  I operated one for a week as a novice and made quite a few CW contacts on 80 and 40 meters.  Of course I was tuning with very steady 14 year old hands at the time. 

The 62A won't fare as well in battle conditions as some of the top vintage receivers but if properly restored (replace the leaky caps and out of tolerance resistors along with a careful alignment) the receiver plays well and has decent selectivity through it six step L/C and single crystal filter setup.

You really do need to recap it to both protect the receiver and return it to the level of performance of which it is capable.   Some of the otherwise difficult to replace caps in the front end are easily accessible if you remove the side compartment that covers the inductors for the top two bands.  You are likely to also find a number of seriously out-of-tolerance resistors.   But once you have it working it is a very nice sounding receiver and nice looking also.

When I got my novice back in 1975 WLS 890 in Chicago was still playing rock and during late winter and spring they put in a beautiful fade free signal to the Mississippi gulf coast by late afternoon.  WLS really cared about their audio in those days and the station sounded great on the SX-62 driving an older Marantz speaker.  Although it is tough to find AM broadcast stations worth listening to now the SX-62 does work very well on FM broadcast where you can find something far better than moronic talk radio.
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Rodger WQ9E
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« Reply #19 on: October 04, 2012, 10:03:30 PM »

Thanks Roger.  That is exactly what I was hoping someone would say. 


Tom
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« Reply #20 on: October 05, 2012, 01:59:27 PM »

Quote
OK....I am looking at the SX-62A.  I know it does not have a band-spread or a Guess Meter.  Is the tuning good enough for say normal AM ragchew on 75M?  I do have a digital readout from N3ZI.

Ive listened with far worse as I was growing up. From table and console radios with only one IF stage and no selectivity options thru a regen and BC-454 after getting my Novice (still listened to 75 AM).

As with the SX-42 and others with only 2 IF stages the skirt selectivity is marginal so none can be considered battle conditions radios where you must accept the fidelity compromises in order to copy.

The 62 tuning is OK for most of the time but the pointer backlash and wobble can be a distraction unless its path is cleaned and set up well. Ive not tried a digital readout.

On FM I consider it outstanding with just a folded dipole taped to the top of the wall. An old set of rabbit ears does better. I use an old DPDT knife switch to select FM/HF-MF antennas.

Carl
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« Reply #21 on: October 05, 2012, 02:11:49 PM »

Not sure if this will work in a SX62 but a noncalibrated bandspread, quick and dirty can be obtained by paralleling the AM/CW (not FM) oscillator cap with a 3 to 15 pf variable.  RF circuits won't track as well but not too critical over small range.  When re-aligning the existing osc. caps set the new cap at about 7 pf, midrange.

If it will work in SX62, I guess the biggest challange is to try to do it with no holes, or change/combine a switch function, freeing up a hole on front panel. You will also want to bring the bandspread shaft out and away from the larger variable osc. bay to keep hand effects to a minimum.

I have done this in a R100/URR "morale" receiver that also had no native bandspread with reasonable results.
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RICK  *W3RSW*
AB3FL
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« Reply #22 on: October 05, 2012, 02:20:00 PM »

With the digital display I have, I don't think there will be much trouble tuning on frequency.  As for a Guess Meter, I could always add one in a separate box like I have for the digital display.  btw Here is the display I have:

http://www.pongrance.com/ddfc-cc.html

I got it with the blue display

Hopefully Sat night or Sunday I will be on AM again.  I had to sell my nc-183 a few months ago

Tom - AB3FL
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« Reply #23 on: October 05, 2012, 04:27:45 PM »

If the SX-62A is going to get you back on AM then it is a GREAT receiver Smiley  Welcome back!

The idea about a fine tuning trimmer cap is a good idea, particularly if you operate on the higher bands.  I have used the calibration control on a HRO-60 for fine tuning on 15 meters.  With the SX-62 I found for 40 meter CW when using the crystal filter positions I could tune more easily by leaving the lid up and directly moving the large pulley connected to the tuning capacitor.  I made a couple of contacts on the 15 meter novice band and it was like tuning an old regen, move your hand to or from the oscillator section for fine tuning.  But on 80 and 40 AM the regular tuning knob should work just fine for you.

Like Carl said, it does very well on FM.  The SX-62 pulled in stations my Marantz 2285B stereo receiver couldn't although the Marantz did sound a little better on nearby stations.  The 2285B (still have it too) has a very good FM section in it.

For me one of the strongest scent associations with amateur radio is the aroma from the VR tube that was in my first SX-62. I assume it was some combination of the bakelite shell, inner foam, and ever present dust that creates the distinctive smell.
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Rodger WQ9E
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« Reply #24 on: October 06, 2012, 11:51:32 AM »

For fine tuning I would use a varactor; since it is just a diode it is not a major sacrilege. Then all you need is to run a few small wires thru a below chassis hole to the oscillator with a small PS or battery and a pot in a minibox.
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