Connecting vintage shortwave tuner to stereo

E

ErikPSmith

New Member
Hello all,

Here's a question for you all: How does one connect a vintage shortwave tuner to a vintage stereo? That is, when the tuner doesn't have an RCA plug output on the back?

Here's what's going on: I recently acquired a vintage Dynaco tube setup on eBay, and let's say I am very, very happy. OMG, what sound! I guess most readers of this forum will know what I am talking about. I have the Dynaco ST-70, the PAS-3 preamp, the FM-3 tuner. What a night-and-day difference from the transistorized equipment I've been using all my life!

Okay, this vintage tube setup leaves one thing out -- the AM band. And I got to thinking -- since I'm getting vintage stuff, why not get a vintage tuner with more than just AM -- why not get an all-band radio, with shortwave, the whole nine yards? I did some research and found that the Hallicrafters SW-62A is one of the best-regarded tube radios of the late '50s and early '60s. I've noted there are several posts on ham-radio forums that praise its performance on the AM band. And guys, this baby has 15 tubes. This model doesn't have the signal-strength gauges, bandwith controls and dial tuning that hams prefer -- instead it has a cool looking slide-rule type tuning indicator. This model is basically designed for listening. Found one today at a ham radio swap meet for $100.

Now my problem. How do I hook it up? There are unused FM-AM RCA input jacks on the PAS-3 preamp (right and left). So no problem there. But what about the radio?

It has two types of outputs. First, there is a headphone output jack -- the manual says this is designed for high-impedance headphones. And then, on the back, there are screw-terminal speaker outputs. The manual says that these are designed to drive speakers of either 3.2 or 8 ohms. There also is a provision for you to connect a transformer to the radio so that you can drive a speaker of different impedance.

Okay, I am an electronics dummy. Is there any way to use either of these outputs to connect up to a stereo? Or am I better off just taking this beast into a shop and asking them to add an RCA-plug output in the back?

Thanks for any advice,

Erik Smith
Olympia, Wash.
 
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Use the headphone output, i assume that there is a volume control on the
receiver.

Just get a cable with rca-connector at one end and connect to the headphone outlet.
( the nice way would be to install an rca chassies connector in the the receiver, but you
can do that in a second step)
 
Those SX-62s are great candidates to match up to a good mono speaker system. PP 6V6s & a good OPT give a very nice sound. Nice find for a hunski!
 
Cool! I'd been worried that the headphone jack requirement for "high impedance" headphones would make somehow make this incompatible with direct connection to an RCA plug. I ran into a problem once, on a different device, connecting something from the headphone jack into an RCA plug -- sound was all distorted. But if you guys think this might work, what the heck, the parts aren't all that expensive.

Yeah, I've been doing some research on this thing, on the Web. Some folks praise its hi-fi performance. There actually is a "hi-fi" setting on the front. Another cool thing is that I notice someone posted a message on a different forum indicating that he found a way to run the signal through a vintage FM-MPX adapter and get stereo. Not that I need to do that, because I have an FM tuner, but it shows it can be done. Me, I'm astounded at how big and heavy it is -- 65 pounds. But what really blows my mind is that in 1954 (the first year it was made) it sold for $349. That's $3,000 in today's money.

About all I've done so far is to plug it in long enough to see if the dial lights up (it does). The guy at the swap meet swore that it worked the last time he had it plugged in, four years ago; grease-pencil marks on the dial indicate that he had some favorite spots on the shortwave bands, so those must have worked. I forgot to ask if he had replaced the capacitors, the usual trouble spot on old equipment. But I'll betcha someone must have done the work if it's still working.
 
I did this as a teen with my father's Hallicrafters S28d (that I restored recently - it needed massive recapping and a new transformer).

I am not sure why I did it, but I guess just to goof around. The Halli also has headphone out on the back of the rig, and I just used a simple phono jack and wired it in to the headphone out.

I used that rig for a while as the receiver for a 40 meter 50c5 tube QRP (low power) CW (morse code) transmitter I built in the 80's. I wanted to experience 1950's Amateur Radio operation in the purest sense. That did it! :)
 
The 600 ohm output will do OK, but you'll have to mind the volume on the Halli so it doesn't over-drive the rest of the amp. Consider you're feeding a couple watts of power into something that was intended to see milliwatts.


A better way to do this would be to tap the output on the Halli upstream of it's audio amp. Basically find the volume knob, and connect to the high side of the volume pot for your output. There should be 3 wires on it. One goes to ground. One is the center wiper, which is the connection to the audio amp, the other is the high side terminal which is output from the radio detector itself.


Also, just as a mention, if the Halli is in original unrestored condition, you may want to consider having it overhauled just for proper performance and safety reasons. If its in for a rebuild, it would be a small matter to add the line-out connection at that time. I wouldn't take bets that its not absolutely original. I rebuilt a National from that time period that my boss found on the dump. It had all original parts in it. It did work, though it worked a hell of a lot better after I replaced all of the bad caps and resistors inside. Tubes are amazingly tolerant of things being out of spec.
 
Like any old gear, you might want to check for electrical safety. sometimes there is a cap between the chassis and AC line that can short. check that before plugging it into your stereo!
 
Yeah, the safety stuff is a concern for me. I have been doing some reading on the Web about the electric shock hazards posed by certain models of radios, including the lower-end Hallicrafters models. I'm stunned that anything that unsafe was ever sold to the general public, but I guess that was common practice in the '40s and '50s. This one doesn't have a grounded plug, but at least it uses a transformer. I really don't have the expertise to work on something like this, and I am not eager to remove the chassis so I can look underneath to see what was done to it. I guess I did one thing that isn't recommended with something like this -- I plugged it in to see if the dial lit up, which it did, and then I immediately shut it off.

So part of me wants to hook it up to the stereo right away and see if it actually picks up anything -- the guy swore it worked -- and part of me is thinking, take it in to a shop first, ask 'em to put in an RCA plug, and give it a once-over to see if there is anything else wrong with it. Oh, it is so tempting to just play with my new toy!
 
The hot chassis stuff was actually perfectly safe when used in it's original cabinet without modifications. Or at least the stuff in plastic or wood cabinets was. The metal ones, no idea WTF they were thinking on that. There are insulators between the chassis and box but that sort of thing worries me.
 
Shortwave does not provide a 24/7 stabile & high audio quality signal unless you are in Europe near the AM entertainment broadcast shortwave stations. Connecting thru your Dyanco set up will not improve the sound much.

How about a stand alone shortwave receiver?
 
Oh, the real idea here was to get a great-sounding AM tuner... something I could play through my stereo, to complement the vintage FM stereo tuner -- the Dynaco FM-3 is FM-only. The shortwave bands are sort of icing on the cake. But I do have to think it'll be cool to be able to listen to everything, the entire radio spectrum, on my big room-filling system. On shortwave I certainly wouldn't expect to hear anything like the quality of FM radio, but that's not really the point.

Even though AM is dominated by talk radio these days, in every town of America there's usually at least one AM music station left, sometimes more. So on the AM band there is still some stuff worth listening to. People forget that AM can actually sound pretty good if you have a decent radio, but most AM radios these days are pretty awful. But that's not all. This is a radio that can tune in the entire spectrum as it existed when it was made in 1954. It is unusual to see a vintage tube-type shortwave radio that includes both AM and FM. And it is the entire FM band to boot, the frequencies that were used for broadcasting from the late '30 through the late '40s as well as the modern FM broadcast portion. (If you look at the very earliest FM radios, you'll see that they pick up entirely different frequencies. I have to wonder -- what is the original FM band used for, anyway? Guess I'll find out.)

You know, there's something about a stereo system that does absolutely everything -- records, CDs, AM/FM, home theater, cassettes, reel-to-reel tapes -- and everything there is to be heard on radio.

Standalone? Actually, this radio is designed to be a standalone set, as are most radios of this type -- just connect up a speaker. It contains a 10W tube amp. (There's even an auxilliary RCA input marked 'phono' -- the manual says you need to use a high-output phono cartridge -- but there is no indication in the manual that it provides equalization, you know, via the RIAA curve or any sort of curve -- so I wonder how well that would work. I suspect some sort of preamp would be needed.)

* * *

I should add -- I did a little bit of research here before I took the plunge and bought something. I tried to find out if there was some sort of vintage piece of tube-type equipment that combined AM and shortwave in some sort of a tuner component that was designed to be part of a stereo system. I found out there was at least one well-regarded tuner of this type -- the Hallicrafters S-118 of 1961. It actually looks like sort of like a vintage stereo component, and the ads boasted that there was an RCA jack in the back so that you could hook it to your hi-fi. This one seems to be a rather hard-to-find model. It's not worth much -- hams disdain it -- and I gather it must not have sold very well. There's another Hallicrafters model of the same vintage, the S-120, that sort of looks like it, but Web comments seem to indicate that it is one of the worst-regarded radios from this venerable firm. And finally, there is a common Hallicrafters model that has AM and shortwave and a really kinda-wild looking '50s-vintage faceplate -- the S-38E -- but this is a hot-chassis model, no transformer, and now that I've read up on them there is no way I'm going to touch a radio like that -- especially one with a metal case.

I also found that that there was a Lafayette tube-type AM/Shortwave tuner that had sort of the right look in the late '60s, with a brushed-aluminum case that really does look like a piece of home-audio equipment -- it was called the "Explor-Air Mark V." But I couldn't find anyone on the Web with nice things to say about it, and the dial looks so much like the maligned Hallicrafters S-120, I was suspicious it might be the same radio.

Anyway, when I went to this radio swap meet yesterday, I told myself I was looking for either the Hallicrafters SX-62 or the S-118, and the much-fancier SX-62 was the one I landed on.
 
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For great sounding AM a vintage simulcast stereo tuner would be hard to beat.

Sent from my SCH-I605 using Tapatalk
 
Well, I just brought it in to an electronics repair shop and asked 'em to have a look and wire in an RCA output jack, as suggested here. I also asked 'em to advise me on whether it would be safer to install a polarized and/or grounded cord -- I know that on some tube equipment a grounded cord is actually a bad idea. We'll see how it turns out!
 
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