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Tuesday, April 19, 2016

Pigs, Lipstick, and my old Hallicrafters S38 "Widow Maker"


I blame Grayson for this.  After getting my old 6U8 superhet running nicely on 80 and 40, my attention turned to an old Hallicrafters S38-E that had been relegated to the car port (Armand saw it out there, looking abandoned.)  I didn't like it because of its "transformer-less" "widow-maker" power supply. I was afraid to even GIVE it away for fear that someone would electrocute themselves.  But Antique Electronics Supply had an isolation transformer, so the order went in.

I have to rewind or replace one of the primaries on the input antenna coil.  This was a victim of the original cheapo power supply.  Apparently the antenna terminal got grounded when the chassis was "hot."  POOF -- smoke was released.    

The bands do seem to sound better through thermatrons... And there is an undeniable 3-D aspect to working on these old rigs.

So yes, in a certain sense  REAL RADIOS GLOW IN THE DARK.

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Bill, I think that as long as you don't work on it in the car port in your bare feet you'll be fine!  Good luck with it and don't blame Grayson too much.  I think it was destined to come back in the house eventually.  The radio gods have been whispering in your ear!
 Ciao! & 73, Armand

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Bill:
I’ll take the blame, no problem!
S38 is nice to work on, plenty of room, no magnifying glass required.  But I have to admit I am not a big fan of working on low cost AC line powered “raft-anchors” (too little for a boat).  Definitely give it a isolation xformer and replace the filter cap(s).  If it doesn’t weight 50+lbs, a bit lightweight for me.
If you need a good thermatron homebrew project (and who doesn’t really), I’ll send you plans for a nice 4-thermatron (including compactron) AM/CW 20/40M 5 watt transmitter I am finishing up (90% of the work is “finishing up”).   Designed from scratch.  Actually works.  Uses a new construction technique I’ve been working on. 
Grayson
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Hi Bill,
As I read about your next project – kept thinking –you can put lipstick on a pig BUT it is still a pig. I had one and put an isolation transformer on the front end –but found I was showing signs of carpal tunnel syndrome on my left hand as I kept retuning the radio because it drifted so much. Have fun.
Pete

Pete:
I don't know.  Simplicity is a virtue, and this thing is pretty simple: RF amp, mixer, LC oscillator, detector, audio amps.  Broad as a barn door with just two 455 kc IF transformers for the filter. Lots of room on the chassis. 
As for drift, my little 6u8 RX with LC oscillators in both LO and BFO settles down very nicely. 
Bill
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Hi Bill,
 I surely didn’t mean to denigrate your next homebrew project and perhaps it was that the one I had was a  dud in the lot.
 But I then moved up to the SX-99 and was in tall clover. Besides today we have some things we can do to enable “tamer” oscillators. So why not? You need to team that up with the M^3 and make some contacts.
 Pete
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Pete: I KNEW  you would try to get a synthesizer of some sort inside the S38-E.  But I say NO!  I had a lot of fun getting the LC oscillators in my 6U8 rig to tune exactly where I wanted them to tune.  You know, play around with the cap in series with the main tuning cap to change the tuning rate (better than removing plates -- they are hard to put back on!).  Then changing the values of the L and C elements to get the thing to oscillate in the desired range.  Then wrap it all up with some Dymo tape on the 1/2 CD "tuning dial."   Sure, I know, that would have been a few keystrokes on the Arduino, but somehow this old way puts you closer to the physics, closer to the electrons. Take a look at the e-mail about Wooden Boats, VFOs and PTOs on yesterday's SS blog. 

The "widow maker" potential of the S38-E was apparently on the minds of the guys who designed the cabinet. The whole box and the front panel are all very carefully insulated from the chassis.  Plastic nuts!

Nice looking pig, by the way.  She may appear on the blog soon. 

73  Bill



8 comments:

  1. The definitive ac/dc shortwave radio was described in "QST" in May r June of 1971.

    Someone took an All American Five, plentiful at the time, and added an isolation transformer. They added some regeneration in the IF stage for better selectivity. Then a transistor BFO. They changed the loop to a shielded coil (so no unwanted pickup of local stations), and transistor converter.

    Not that far from some of the modified S-38s, but surely better performance.

    Michael

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  3. Bill, no widows get made as long as the chassis is connected to the neutral wire. If it's not at least there's the thrill. A bit like risking death in the heat of a polo match. For extra thrill leave the case at a car body shop snd tell them to paint it and over cure it the same color as their next job. Mine came out BMW black. With a more pretentious radio I might not have dared.

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  4. A good RCD on the supply, an isolating transformer, and one hand in the pocket has got me to 52, love the old hallicrafters, and by association, pigs in lipstick. Go for it!

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  5. I occasionally pair my S-38B with a 6L6 transmitter on 40, and the drift is reasonably manageable. It's a lot of fun when the band isn't terribly crowded.

    Mine does have a transistorized BFO; the regenerative IF scheme Halli used is pretty awful.

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  6. Maybe S-38E could be the next SolderSmoke Mascot. She is a mobile ham you know.

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    1. She's a drifter. :-)

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  7. Bill,

    This one hurts deep down. My first receiver, as a novice Ham in 1957 was an S38, although my history with it goes back well before then. My father bought it new in 1946. The original version. My uncle (who I believe had the Knack), connected the audio output to a stand alone 40 W audio amp which drove a 12" woofer with a very heavy magnet. He said it came from a movie theater. This whole arrangement was installed into a large wood cabinet which my father built. The top could be raised and held in place with locking hinges. The S38 sat in a special cut out at a 45 degree angle, with the speaker behind a cloth grill below. Next to the receiver was a 78 RPM turn table could be switched to the amp. It was very handsome and was prominent in our living room.

    At a very early age (probably 5 or 6) I was allowed to turn it on and tune in WOR in NY. Home of the John Gambling Show every morning, and of course Jean Shephard later in the day.

    Once a year my father would extract the S38 from the cabinet and take it on our vacation to the Jersey Shore where he would listen to the fishing boats on 2.5 Mhz AM. I'm not sure what information he gleaned from this communications, it all was a mass of heterodynes to me. But he would usually bring home fish.

    When I eventually got my ham license at age 12, it moved to the operating table. Of course I did not know anything about the lack of a transformer and I'm sure my father didn't either.

    In fact I don't care that it is looked down upon so much, I still have this radio and have no plans to give it up, or to try to turn it on for that matter. It sits in a place of honor in my shack today. It's missing some of the original knobs and I'm always on the look out for them. But after 70 years of ownership in my family, it's technical shortcomings are not an issue.

    Bill, the lipstick on the pig image is painful and I suggest not appropriate. Hallicrafters sold many thousands of S38's and their subsequent versions in the 40's and 50's, which made the Ham Bands available to many who would not have spent money for anything more expense. It probably made a significant contribution to the growth of the hobby. Was it a good ham receiver for the long term? No. But it was an important receiver.

    Fairly soon my novice station added a series of better receivers, and the S38 went back into its wood cabinet. I barely remember anything about these subsequent receivers, but I do remember making some of my first QSO's through the QRM from Radio Moscow, and achieving enough satisfaction to keep me in the hobby.

    The bottom line is. It is what it is. It will never be a great receiver even if you fix the transformer issue. Accept it or go in a different direction.

    If my father had not bought that receiver I might not be a Ham today.

    Sorry for all the nostalgia.

    73, Dave, K1KA

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