I have a Hallicrafters S-85 shortwave radio that I would like to restore. It's a radio I grew up with so the restoration is more for personal reasons rather than value or a collection. Are there resources out there for parts and service? An internet search turns up some places that deal with old radios but since it's not something I have dealt with before I would value some recomendations.
I believe these are hot chassis sets, and if so, discussion isn't allowed on DIYaudio. If true, you'll need to take a lot of precautions to use safely.
Either way, don't just plug it in to test it if it's been sitting for years. It will need to be brought up slowly, preferably with a Variac, and you'll definitely want to replace all electrolytic capacitors. What is your current experience level?
But first, find out if it's hot chassis. Getting these to modern levels of safety is not trivial, but can be done. But this may not be the place to discuss it.
All good fortune,
Chris
Either way, don't just plug it in to test it if it's been sitting for years. It will need to be brought up slowly, preferably with a Variac, and you'll definitely want to replace all electrolytic capacitors. What is your current experience level?
But first, find out if it's hot chassis. Getting these to modern levels of safety is not trivial, but can be done. But this may not be the place to discuss it.
All good fortune,
Chris
The full product manual is here.
The PSU fragment I snipped out shows things as being not that bad. The unit is easily brought up to modern standards by eliminating the C56 "death cap." and the installation of a 3 wire, safety grounded, power cable. 🙂
The PSU fragment I snipped out shows things as being not that bad. The unit is easily brought up to modern standards by eliminating the C56 "death cap." and the installation of a 3 wire, safety grounded, power cable. 🙂
Attachments
To my knowledge, S-85 is not a hot chassis radio like the well known S-38. Nice chassis, higly collectable and well worth of a restoration. This kind of radios aren't difficult to restore, provided that one isn't seeking to reach the original factory performance (that wasn't great even then), because the chassis is not cramped, parts are generic, and the service manual is online. I would start by downoading the manual. It does also have a useful voltage chart page. I usually don'even try to power up the radio before checking continuity and insulation of the power transformer windings, and replacing all the filter capacitors on the supply circuit and the coupling capacitor on the grid of the audio output tube. Then I make sure that the power supply and audio amplifier section are working, and I go back from there up to the RF section if needed.
Excellent news! And lots of good advice already. You'll also want a fuse in the primary circuit, which should be the first thing in in the line/live path.
All the best,
Chris
All the best,
Chris
Apart from checking / replacing electrolytic caps in the powersupply there is not much you can do.
Aligning and adjustment needs instruments and manual. Haphazardly changing tubes and components will not make it better and would in fact reduce it's market value considerably.
Excellent information thank you. My intention is to bring the unit back up to good working condition. The only changes I plan beyond cap replacement would be safety related and finding an appropriate speaker since that has been replaced with something that looks wrongly sized. Hopefully this gets it working. Cosmetically it has some issues but I like the idea of leaving some patina and just doing a good cleaning. Some questions.
For proper grounding then I just bypass the "death cap" and make sure that connects to chassis ground along with the safety ground from the power cord? As far as the fuse goes would a 2A amp slow blow be appropriate? Basically wire it up the same as my Tubelab SSE.
After I get it working would it be worth having someone else align and adjust it? Are there people who offer this service?
For proper grounding then I just bypass the "death cap" and make sure that connects to chassis ground along with the safety ground from the power cord? As far as the fuse goes would a 2A amp slow blow be appropriate? Basically wire it up the same as my Tubelab SSE.
After I get it working would it be worth having someone else align and adjust it? Are there people who offer this service?
Just cut off and remove the death capacitor entirely. Don't attempt to replace, it should not be there.
I have an S-85, which I bought from the original owner, it looks great and still works well.
I have an S-85, which I bought from the original owner, it looks great and still works well.
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The manual I previously linked discusses alignment. If the info. seems overwhelming, get connected with a local "ham" radio operators group.
Yes, wiring like the primary side of the SSE is good.
The rated power consumption is 85 watts, so a 2 amp fuse would be too big. A 1 amp slow blow is probably good, but might be close to blowing in high line voltage conditions. If it blows move up to the next available value, probably 1.25, 1.5 or 1.6 amps.
If the radio works good don't mess with any alignment screws yourself. Use it for a month or so in it's new environment before making an alignment decision since the old coils and mica need to have all the moisture baked out of them before doing anything.
If the dial is too far off, or reception is weak alignment may help, but only if done by someone with a decent signal generator and who knows how to follow the procedure in the book. It's pretty simple, but blindly turning screws can mess it up good.
Yes I see, looking at the schematic again that makes sense. A fuse and grounded power cord would be the only add then for safety.
It looks like a cut down later version of my old SX28 used during WW2, same frequency range and IF.
Being war time a lot of the tubes were metal covered, I added another IF stage to it.
Being war time a lot of the tubes were metal covered, I added another IF stage to it.
You may find that using a suitable SW antenna will improve reception more than an alignment will.
One of my childhood memories around this radio is of my Dad disassembling my old swing set and building a huge antenna out of it. I plan to do something less than that but did think a good antenna would be in the mix.
The manual states that the unit came with a 15 foot wire to be used as an antenna.
A 1/2 wave dipole cut to the length suited to the band of interest will outperform a "long" wire. That too is described in the previously linked manual.
The BFO (beat frequency oscillator) in the unit is for receiving CW (continuous wave), AKA Morse Code. CW is very, very, rare nowadays. However, that BFO might be adapted to receiving suppressed carrier signals, like SSB and DSB. Again, a local "ham" group is the place to get help with that.
A 1/2 wave dipole cut to the length suited to the band of interest will outperform a "long" wire. That too is described in the previously linked manual.
The BFO (beat frequency oscillator) in the unit is for receiving CW (continuous wave), AKA Morse Code. CW is very, very, rare nowadays. However, that BFO might be adapted to receiving suppressed carrier signals, like SSB and DSB. Again, a local "ham" group is the place to get help with that.
CW is not so rare that the CW portions of the ham bands become so crowded that only a modern receiver with a very narrow bandwidth (200 Hz or less, usually by DSP) can separate them all. Especially true during a contest or band opening.
That schematic is very similar to the S-40B that I had as a kid. Of course I "tuned it up" without a signal generator, and If I remember right found a small boost in sensitivity to be had by swapping 6SG7's into the IF stages instead of the 6SK7's. That old radio along with a "rock bound" ARC-5 transmitter and DIY power supply on 40 meters would have been my first ham station in the mid 60's if my father had ever gotten around to taking me to the FCC office for the license test. He would toss both into the trash around 1970.
I finally got my license in the 80's at the Miami hamfest.
That schematic is very similar to the S-40B that I had as a kid. Of course I "tuned it up" without a signal generator, and If I remember right found a small boost in sensitivity to be had by swapping 6SG7's into the IF stages instead of the 6SK7's. That old radio along with a "rock bound" ARC-5 transmitter and DIY power supply on 40 meters would have been my first ham station in the mid 60's if my father had ever gotten around to taking me to the FCC office for the license test. He would toss both into the trash around 1970.
I finally got my license in the 80's at the Miami hamfest.
The A2 aerial ( antenna ) input is for the top end band .
Why don't you build an antenna tuner ,I have built several so you can match the impedance of the antenna , I have built several to different designs , its not hard to do --yes it does make a big difference--several "S" points ?
Here is some types -
G4NSJ - ATU AMU aerial antenna tuning matching units - Radio WorkshopRadio Workshop
If you can find one the British armed services in WW2 came out with the No.19 set , this set had a high quality "aerial variometer " as it was called there was a USA and UK version.
Why don't you build an antenna tuner ,I have built several so you can match the impedance of the antenna , I have built several to different designs , its not hard to do --yes it does make a big difference--several "S" points ?
Here is some types -
G4NSJ - ATU AMU aerial antenna tuning matching units - Radio WorkshopRadio Workshop
If you can find one the British armed services in WW2 came out with the No.19 set , this set had a high quality "aerial variometer " as it was called there was a USA and UK version.
I apologize if this is obvious, but no one mentioned this: a common mistake of inexperienced restorers of point-to-point tube radios is to mass-replace all the capacitors on the HF section, and rearrange them in neat way while they are at it. This will mess-up the alignement or even introduce unwanted couplings and oscillations. Avoid moving components that are placed before the volume potentiometer, and change them one at a time.
Nothing is too obvious to mention in my case 🙂 I noted that the suggestion was to replace the caps in the power supply and also see that the schematic contains some "gimmick" caps so figured it best to leave everything else alone till I understand more.
You will need to get away from the "audio mentality " a radio is basically a variable tuned circuit that receives its signal via the either that's why it was called in the UK --"Wireless " --no wires .
Tuned circuit in old school radio equipment have a large number of very small value capacitors to help tune the radio to the frequencies required in conjunction with an RF coil and a variable air spaced capacitor to vary that tuned circuit across a radio band then converted to an intermediate frequency determined by the designer eventually leading to something here will people recognise --an audio section.
Of course its all in a chip now but chip radios don't interest me only the stuff we are talking about here.
Tuned circuit in old school radio equipment have a large number of very small value capacitors to help tune the radio to the frequencies required in conjunction with an RF coil and a variable air spaced capacitor to vary that tuned circuit across a radio band then converted to an intermediate frequency determined by the designer eventually leading to something here will people recognise --an audio section.
Of course its all in a chip now but chip radios don't interest me only the stuff we are talking about here.