When I was a kid back in the 50's, I'd routinely get zapped off metal cased radios. I learned to isolate myself instinctively and to flip the polarity around with the plug. It wasn't just radios that had this issue. I noticed it too with certain appliances like toasters and refrigerators. Amazing times back then.
Had an old one as a kid and it used to give me a tickle all the time until I mentioned it to a local Ham G3RXH. He explained it was an All American 5 underneath and told me to get a 1:1 mains transformer from a bathroom shaver socket and put that in between the radio and the mains. He was a kind man, my Elmer. R.I.P. Howard.
They only had four tubes, 50C5, 35W4, 12AV6, and 12BE6. No RF amp, straight into the mixer. Radio had lots of images. I bought the S-meter kit for mine. My dad had a little electronics experience and after finding which blade on the power plug went to the on-off switch he marked the plug so I wouldn't get shocked.
Some of these older receivers don't even have a fuse, let alone polarized power cables, wonder how many folks back in the day would actually gotten zapped! I just uploaded a video where i installed a fuse and a polarized cable on a Hallicrafters. Thanks for the info!
These are all great comments! I acknowledge that some folks are unable to accept the level of risk associated with AC/DC sets or having a handgun in the house, or owning a pool, or flying, or a dog, no matter the measures taken. And it's not personal. Most of us hams consider the novice or untrained and what might happen to that kid as the worst case. Insurance companies have to consider the general public and completely untrained against any benefit to the manufacturers or the public, and make a guess as to a level of safety that is acceptable. So even if there is some safety level associated with say - the Specific Absorption Rate of RF against your head with your mobile phone, and it is tested in a lab, some still may not be comfortable with it. That's Normal.
Thanks for the trip down memory lane. My dad gave me one in the mid 60's and I had it until the 80's. It got me on my way to getting my ham ticket. I loved that radio.
I recapped my Hallicrafters S-120 and made a 2-part video here on UA-cam (Jan 2021). As I recall, it was a nightmare to work on. I had to rely on 2 parts radios. One was a Lafayette HE-40. Almost identical, except it also had an S-Meter. Even after the recap, I had to work on reducing the hum. I sold it at NEAR-Fest soon after. It went to a good home. It was nice to see you there at NEAR-Fest. I think I saw this radio on your table, and we talked about it. 73 Paul AA1SU
More common than the shortwave radios were the two wire, non-polarized "All American Five" AM radios, such as the clock-radios found in kitchens all around the country during the 60's. Somehow most of us survived.
The advantage with these table radios was that we were not attaching stuff like antennas and ground, headphones, tape recorders, and so on. Plus, everything was insulated, even the knobs.
@@MIKROWAVE1 Almost - My Emerson 547 was fine as long as 1. You used the supplied knobs. 2 Didn't try to hook up an external antenna, and 3. DIDN"T TOUCH the screws on the bottom of the radio. I found that out when I was about 14. Many years ago now.
@@jrkorman i have one of those, not common to find them or any american set here in the uk, also have a few others, most use a 'semi isolated' chassis , with chassis isolated from direct connection to circuit negative via a cap and resistor, but this emerson isnt! dunno why they didnt do it as knobs come off very easily exposing live spindles, plus those live screws on the bottom! UK and europe made/designed acdc sets had to use good safety practices as our mains is double the US but strangely almost never used the capacitor isolated chassis idea apart from 3 models i know of, i have 2 of them
Ya - notice those radios were encased in a Bakelite case and the knobs were also insulated too! I'm from that era and remember those 'hot' chassis too.
Hey! Former Project Manager at U.L. in the early 2000s, specifically in Wire & Cable but I also mingled in all other fields too. Companies don't submit reports to be certified. They send in a sample of their product and then it is thoroughly tested by the engineers. For instance, in W&C, there would be burn tests, crush tests and the like. In plain English, if stuff didn't burn more than it was supposed to, or break down with less force than was reasonable, then it got the seal of approval. There is always a battery of tests suitable for the field the product falls into. Basically, U.L. makes the report and not the submitting company. Rock on.
Thanks for this Chris! I have never been through a UL process, but one company I worked for did submit FM (Factory Mutual) for some products. I was doing FCC Type Certs and Military and FAA Aircraft lab testing and submissions regularly in various companies. So what you are saying is that Hallicrafters would have had to send a sample radio in for testing in the lab, especially in 1960...
Across your hand even without the network the 120v wouldn't kill you. You would get enough of a shock to violently jerk your hand away, and that could injure you. However, if you touched the "hot" ground with your hand, but your other hand was grounded, now you have a current path that goes through your trunk, which could shock your heart and cause cardiac arrest. The current required for that is just a few tens of MA. Wet your hands in brime and then measure your skin resistance. It could be less than 1000 ohms! Sweat will do that too! BTW, while Knight Kit designed the Star Romer with 6.3 volt tubes and a power transformer, Heathkit had several models that used the standard All American 5 tube set, BUT they had a 1:1 isolation transformer in the power supply.
If you don't have an isulation transformer. You can make your own by connecting a filament transformer to another one in reverse connect the two filament sides together and use the two primaries to hook up the radio. Make sure the secondaries are in phase with each other. Use a scope then you don't have to open up the transformer. I'm sure the net has the know how. 73
I feel fortunate that I survived my experience of learning about AC/DC sets early on when I started restoring antique radios. I lovingly refer to my 1950 Silvertone Model 2 as the "little radio of death" since it has a metal case that had a 50% chance of being electrically hot even when it was turned off. While holding onto the PL-259 end of my amateur radio antenna (which was grounded), I leaned on top of that radio with my elbow by mistake. I put a polarized plug on it after my arm stopped tingling.
Early on in my radio days I was told to keep one hand in my pocket if i am working on a live circuit. That probably saved my life more than once when I was a teenager
I got hit really bad twice as a teen on shiny ungrounded hand drills - both were 120VAC. The 500 to 700V DC hits on my early power supplies for ham stuff Hurt and Zap, but not as bad as the through the body 120.
I used to have a Hallicrafters S-86 half a life time (15 years) ago. There are a few videos of it way down on my UA-cam channel. The first time i was gonna test it, i almost touched the case. I knew it was an AC/DC set, but all Philips ac/dc sets are completely safe and well engineered so i thought 'Eh, it'll be fine'. But a little voice nagged and made me measure for voltage, and there was the full 230v mains on the case. After recapping the thing, the short was still there. I never got around to actually finding that short. For a couple of weeks i used it like that, just measuring the voltage each time, but shortly aftermaking the video on my channel i hardwired a 230v-110v isolation transformer into mains cord, and ripped out the 220v-110v autotransformer. I eventually sold it to a friend who knows his way around mains safety, explicitely notifying him of the issue. So yeah, those Hallicrafters things are pretty dangerous. Incomparable to the Philips AC/DC sets i'm used to.
230V is more challenging but that did not dissuade Euro manufacturers from trying AC/DC to save some $. The autotransformer idea is interesting - and scary!
@@MIKROWAVE1 philps acdc sets are 'usually' very safe designed, but in this case maybe some previous 'engineer' /owner has done a 'bodge' ruining safety
I'd like to see how to properly rewire an old piece of gear for a modern 3 prong plug. Many sites will just say "Of course I rewired the radio to a modern plug.." But do not show what is done safely....
There are more important issues with such old stuff that you gotta fix before rewiring the plug - you gotta verify that the PSU electrolytics are not electrically leaky, and replace at least a couple of the wax paper capacitors. With that i mean that if you rewire the mains cable - which is a good idea in itself - and start using it, you'll likely blow stuff up that's worn out from being over 60 years old. But the basic concept is simple: get a vintage looking but modern cable and plug. Live to live, neutral to neutral, earth connected to a heavy duty solder lug that you put under an existing nut and bolt connection on the chassis.
@@mfbfreak All great advice. Some older sets simply do not have separate power ground but use chassis for everything. These are real widowmakers that require true isolation because you can not use the 3 wire plug idea unless you lift everything off chassis and make a separate ground bus. It go Boom. The best you can do is to use a new polarized cord and guarantee that the outlet is wired right - and test it. Still dangerous. For table radios with plastic cases and knobs this worked. But with Ham gear where you attach stuff like antennas and headphones, Keys and a Ground wire - trouble.
The end of an era with so many shortwave stations going silent. Oh but I do have good news. When I was in the old country on vacation in Amsterdam- I noticed that they seem to have many new women riding bicycles!
In the 1980s I used my Hallicrafters sw 500 to listen to cordless phones around 1.7mhz, I used to reverse the plug in the wall socket and the radio would oscillate, and It would jamm the cordless phones. for a 1/2 mile radius.😄
Though everything you said is true, I would still treat that type of technology like a hand weapon. It is always loaded even when it isn't. That safety capacitor could experience a freak isolation breakdown. A small piece of detritus could dislodge inside the chassis and short something. An insect could carbonize between to points of high potential. Highly unlikely? Certainly. But, unless it is transformer isolated, I would consider it risky at best. In my own defense, I love these old radios. I am simply preaching caution. You only have to be wrong once. Then it's too late.
I was given a Hallicrafters as a child, too young to appreciate what it was. I don't even know what happened to it. All older electronics were not built to the same standard as new ones. Safety capacitors Y or X types had not been invented and metal chassis were often powered by one side of the line. Used to listen to Hawaii radio from Los Angeles. Never trust old electronics the way you might trust quality new equipment, which includes things as minor as using it with bare feet on a tile floor. C30 should be a Y-rated capacitor. I would love to have that radio now.
Reminds me of playing through an old guitar amplifier. "Hey, it tickles!" All fun and games until you touch your lips to a microphone and wind up laying on the floor seeing stars, or worse maybe seeing your maker.
Back in highdchool on the late 60s everything i built was tube & powered directly off the 117V AC line...receivers, AM transmitters, guitar amps for my brother's rock band
Although dangerous during certain conditions and component failures, this was indeed considered as "acceptable risk" during that time period. It still is in many appliances. Hence the UL approval.
Great information. This goes for any AA5 receiver on knowing it's limitations and how to improve the situation to make these radios safe as posible. Thanks for making this video Mike. Steve
many seem to use capacitor isolated chassis, i have a few, uncommon here in the uk, and less an issue with plastic or wood cabinets, but still have to watch out for control spindles and external connections, our mains is double the US but the capacitor isolated chassis idea was surprisingly almost never used
My S-120 never tried to kill me, but I was shocked (literally and physically) as a 14 year old when my S-38 tried to bite me! My S-19R with onboard isolating transformer has always been a peaceable Sky Buddy of radio😃- DE K1TB
Valve (tube) tv sets in the UK were non-isolated and remember that's at 240 volts, fine to fix in the workshop with an isolated bench supply, but you had to be very careful in customers homes. I remember at one house, every time I unplugged the set, the customer who I suspect was suffering from early dementia, plugged it back in. I only noticed because the filaments started to glow. I also remember on numerous occasions, having to quickly grab the arm of an enquiring customer as it delved into the back of their live set. Luckily I didn't do that job for long, I don't think that my nerves would have held out. Steve
I typically use a polarized 3 wire plug. Connecting the green safety ground to exposed metal parts when possible. If the chassis is “hot” , I connect the neutral (white, current carrying conductor) to the chassis. This can put the line side 120 v on the antennae as shown in-the video. The best way is to always use an isolation transformer. A safety ground is only supposed to be active in case of a ground fault, normally never carry current. The white neutral always carries return current. Neutral and safety ground return to the same point, but the safety ground is typically less resistance and shorter path to ground.
It would seem like a good idea to put a high value resistance on the antenna connection to the tuning coil, and also between the low side of the coil and ground. Current surges on the neutral bus, and high static charges on the antenna can burn out the tuning coils.
@@ebones6957 This happened to me with a small surplus R-508 aircraft receiver That I did a back of set AC/DC supply for. It had a 24V transformer and a simple voltage doubler off the line. Very clever and very dangerous - and published in some old article. Well you guessed it, The cassis was hot and the little antenna touched ground. Pop! there went the front end coils.
I still have my s-120 I purchased used from a pawn shop back in the 1979’s. Paid way too much for it. Generally a nice SWL receiver and a touchy ham receiver.
@@mfbfreak It works, so I don't fret over it. Thanks. Too many other things to get done. Those other times were on equipment decades ago. I never quite "got" the polarity of A/C, but now I do.
Personally, I would make it a 3-wire cord and not rely on the polarized plug, which is easily reversed using a worn-out extension-cord! I really think that it was a huge-mistake to make any ham-equipment line-operated since there is much more chances of both the 'novice' getting inside it and various hook-ups that might be made while experimenting with antennas and such. Finally, the immediate danger of hooking test-equipment to the receiver and depending on that person either having an isolation xfmr (ha-ha back then!) or automatically knowing to check the potential difference beforehand! 73... Edit: There is another reason I feel this is bad: The first time someone without knowledge of this phenomena gets a 'tingle', the radio is probably going in the trash can or will at-best become a shelf queen!
@@SpinStar1956 yep, i would probably fit a 3 core mains lead in this circumstance, some UK sets, eg. eddystone 840C used this idea, inner chassis was 'live' but isolated from the earthed outer case by plastic standoffs
I once owned a Hallicrafters S-120. It has what is known as a "hot" chassis. Plug it in the wrong way and you got zapped. My Mom and Dad owned a Muntz tv way back in the day also. That television also had a hot chassis. I remember very well getting shocked by that thing.
Muntz is a great story. He would sneak into the lab and cut the parts out that the engineers would put in to any new chassis and see if the set would still work in the big signal metropolitan NY area. If it did, the parts stayed out. That was how he reduced costs to make a super cheap set!
Excellent illustration of early line isolation. I might mention the show and tell part of would you feel this; the completed circuit path was between two fingers on the same hand; Old timers voltage tester. May be a little more noticeable if it passed through your body with your heart in the path. Also pre GFCI days threshold of 30 ma. I can understand not wanting to complicate the issue. Thanks for a easy to understand video.
I liked it. I have a eico signal generator that I replaced the 2 line to chassis cap with safety caps and left them in. It'll tickle you a bit, but it's not going to hurt anyone, plus I didn't want a second ground path when using it. Some people have no risk tolerance.
I have 2 S-120's. 1 for parts. The other for posterity on my shelf. Not that great a receiver, but hey, I have one! And the 50C5 runs smok'n hot!! --- Wanted to send you an email about some MOD's, but you don't allow them, so that's that.
Original is great and that has its place in our hobby, but I live on MODS that improve performance and are reversible or provide a logical safety advantage. Seriously nothing I touch is original museum quality stuff. In fact I like to buy broken stuff. I only get nervous when someone says "it works perfectly".
@tubeDude48 both are worthwhile improvements without destroying the set, in my opinion. Now, I might draw the line at drilling a hole on the rear chassis for a fuseholder, but I would go for an internal fuseholder using an existing screwhole.
Modern stuff is built the same way, DVD players, phone chargers, etc. Every two wire swithing power supply, any metal case two wire electronic device. Some stuff like the phone chargers are even unpolarized, you don't get bit because you usually aren't earthed all that well. The only difference is they use safety caps and fairly high voltage resistors.
I still have mine. I got a nasty shock from it the last time i used it. I guess I need to put that kit in it. I broke 4 vertebrae in my back, so I have plenty of time on my hands to fix it.
there was some UK Eddystone models that used 'live' circuitry, the inner chassis was common circuit negstive and connected to one pole of the mains but the outer metal cabinet was isolated from it with plastic spacers and standoffs, potentiometers and controls had their own plastic grommets, AND it was also earthed to mains earth, it had a 3 core mains lead, BUT the plastic insulation and spacing was good enough if you had to use it with a 2 core supply for some reason,
Back when I was a young teen just getting into working on radios, I quickly learned to reverse the plug in order to not feel the tingling or a shock, when touching the chassis or any exposed metal parts. Never made any sense to why direct ac-dc line powered radios were made, by the 1960's how many utilities still served any customers with 105-125 volts DC? These kind are bare minimum sets, just enough parts to have mediocre performance in most designs.
Wow - How did you know? Recently picked up an S-120 and before even touching the thing I downloaded the schematic and identified the exact points that you showed in this video. Thanks for the heads up on the recap kit.
For bench testing AC/DC stuff or any exposed 120 work I have a GFCI outlet in a box with a short power cord, not something you should be tripping often (tests aside) but it will protect you from any real current flowing from live to anywhere except neutral if you screw up.
GFCI are great in properly wired houses and this is a great idea. You would be surprised how many old houses are hay wired and with no ground in sight!
S120 had a hot chassis which cost me money years ago when I had to add an audio amp that was hot chassis also. The receiver was not legally UL approved to even be earth grounded for the antenna. Ended up trading it to a fellow CB/Shortwave listener that used headphones. Lol
Well now you are talking. Getting two widowmakers to interface without trouble. This is where you need your Handi-Tester or a Meter, which of course we never had or had time for...
I have been bitten by that radio many times but not since I was 15 years old - No transformer at all as I recall and series filaments. Ultimate cost cutting back then. This radio did not have an RF amplifier either.
I remember when I was a kid probably 4 or 5 or so I can't exactly remember when but I remember plugging in a clock and my finger got caught between the plastic part of the plug and it was touching the metal prong and oh boy I sure as hell felt that shock it felt like my body was buzzing and it didn't feel like a tickle to me but then again I was a little kid so I felt it more and ever since then I've been super careful when I work on electrical stuff.
As a 22 year old, I built a Philmore ac/dc 3 tube Regen rcvr It was open and dangerous!!!! I got shocked several of times with it's open metal chassis! Hi one stupid!
Interesting how our two countries differed in their thinking on electrical safety. The UK had a 3 pin plug system which prevented reverse polarity and had an earth wire from an early time...BUT they were running at 240V AC and now have dropped it down to 220-230V AC to conform to European standards. 230V shocks are not funny!
@@steviebboy69 Thanks for your comment Steve. What is the voltage in Australia today and is it the same in all states? I'm guessing it might be similar to the European model? 73 Ace
@@acestudioscouk-Ace-G0ACE Here in my state of Victoria it is normally around 240, but I have seen it sag to around 220 in summer. I am sure I read over in the west it is or was 260 V. I am sure those big chunky UK plugs hurt more to stand on by the way.
I am not surprised that the Hallicrafters is better than the Knight (all else being equal). Hallicrafters seems to be especially good for squeezing performance out of budget builds. I am not entirely sure how they pulled it off sometimes, better inductors maybe? I did a Hallicrafters "Continental" for a friend (just a plastic AA5 set) and well, who hasn't done a few mass produced AA5s from the 1950s at some point or another? The Hallicrafters would beat the pants out of all of them in performance AM broadcast dx'ing, yet utilized the same tube lineup to do so. Imagine what they could have done if they'd had more "cost is no object" models and catered to high end ham or military markets.
I got given a Texas star for cb had some mods and it would burn my truck , crazy as it sounds, it’s old 86 Nissan 4x4 but it burnt my reg cd radio above it out the heater connection behind, I key up in beginning it would shut lights off at night but capacitors where grounded to the outside of box when took it apart, I had it redone nothing burnt so far , lights still dim but it talks to Maine from TN
Because I am not set up for decent audio! But I do go for intelligibility at least! I use the camera mic, an old Hand Dynamic sometimes with the camera, and a Boom Electret for annotation on the slides, which you are hearing. They all sound completely different.
Just plug in isolation transformer if you are servicing. Real issue is that mains noise feeds back into the antenna as there is no isolation transformer in these which isolate the noise also
With an isolation transformer in place, generally the station ground can be applied to the ground terminal and noise will reduce now that you have a reference. But most importantly, the Case and Chassis become safe if you get between it and ground.
So, when the dentist says "we need to replace your old mercury fillings by new ceramic implants", you say "No"! Really? I don't see the problem in replacing anything that is old and wrong.
IIRC, the UL rating isnt so much about the electrical safety of the product, as it certifies the product doesnt present a fire hazard,. Adding a polarized Line cord is a big improvement in safety. I believe CSA(Canadian safety organization) required polarized cord long before they became common in the US.
Well VHF AM actually. The Brits came up with the SCR-522 AM Transmitter Receiver and sent the plans over to the USA and we manufactured thousands of them for the fighters. Aircraft went VHF AM quickly after the war except for overseas which to this day still uses SSB on HF. They are starting to deploy NEXTGEN which should start to make digital inroads soon.
You have a point. Since 120VAC is AC, the larger the cap, the more that the Chassis is connected to the outer case. But a 0.1 uF cap itself will limit the current. Its only when that cap leaks or shorts - that trouble starts! Hence the Y capacitors that FAIL OPEN.
@@MIKROWAVE1 thats why they call it the death cap, when I do any restorations I replace the cord with a polarized one, if I was to do one of these today I would most likely put a grounded plug on it
Why not find a spot to mount a 1:1 isolation transformer and be safe no matter how the receiver is plugged in? That is how I have built my bench power supply (a variac, isolation transformer, incandescent bulb and outlet.).
An external converter that took 10m down to the 80M range would be a possible approach. This would be dual conversion and add gain and lower noise figure, too. Typically, this could be done with a 6BZ6 and 6U8 and a crystal.
If you are building a kit you should know the dangers of tube receivers transformer or no transformer. I built a greymark 2 band radio and there was no isolation transformer. Common sense would tell you to take a neon test probe and make sure the chassis is not hot. My first TV had a polarized plug and my Uncle shaved off the neutral side of the plug so the TV could be plugged in an extension cord. I always looked where the neutral is before pluging it in. Some say about headphones but the output already has a transformer so whats the problem just dont mount the jack on the metal part of the radio mount it on the plastic case. These are safety measures you can take to protect against shock. I have one of those radios and i would first check polarity of the line cord. Thats what a multi meter is for. If you are not smart with electricity dont modify a radio. 73
@@MIKROWAVE1 he never messed with the TV just the line cord. I never wiggled anything just remove tubes and take them to radio shack and test them if there was a bad one they could order one. and that tube was replaced for free if it ever quit working. Radio Shack had lifetime warranty on all their tubes they were expensive so you paid for free replacement so it really wasn't free. 73
Good stories though. I knew A guy who could not let go of an Apache HV 750V but he fell and the weight released his hand. All good but the radio followed and smashed him.
Measuring voltage on the chassis with a 10Meg ohm meter doesn’t really tell anything useful. You need to shunt the meter with a reasonable resistance to really make any read of leakage
Excellent point and and yes a lower Z meter like a Simpson would have read less voltage of course, especially on the outer case which has some isolation. That was one reason I included the 10K resistor tests.
I am kind of intrigued by the comments and the perspective of the video. The UL standard may have changed since 1960? Doesn't "dual-insulation" require a thick plastic case? Is the 3-pin plug really acceptable as a polarizing plug? Can a "dual-insulation" equipment be fitted with extra connectors such as "earphones" or "antenna"? If I were a young radio enthusiast, one thing I would like to do is to connect the speaker output to my computer audio input? How difficult would that be to retrofit the instrument with a properly insulated power supply or transformer? The real thing! Why not? Walworth adapters are intrinsically safe. It does not come to mind easily to young people who never knew anything else that mains outlets are dangerous. Even less with high DC voltage. Voila. My two cent. Tube electronics really scares me...
no you can have double/dual insulated devices with metal cases, such as vcrs, digiboxes, etc. , there must be minimum clearances between live parts and the metal case, and 'double insulation' within parts like mains transformers, eg. having a split bobbin, mains on one ,low voltage secondary on the other
The Hallicrafters took extra care to isolate both the Antenna input and Headphone output and Speaker from Chassis. Case is deliberately isolated from Chassis (within reason and "safe" levels). Most AC/DC radios did no go that far. Hook something up and bad things could happen.
Nice content! Wondering if any custom PCBs may help for any upcoming radio projects? If so, would love to supply and reach any collab together if there's a chance! 🤗(PCBWay zoey)
The tedium of doing the parts library is significant. But yes I am heading towards some simple PCB kits to give away to patrons. Like a Paraset circuit in Solid State and in Valve for instance.
As they AGE. The Halli S-120 has double protection. It is a late model AC/DC and they sent it in for UL testing. Protection 1 was separation of Chassis from Neutral (or Hot if plugged in wrong) with proscribed 470K and 0.047 uF 600V cap. and 2. They went as far as isolating Chassis from Case mechanically. And even isolated the Phone Jack with shoulder washers floating the secondary of the speaker transformer. So nowhere near the killer of the typical 40's AC/DC.
When I was a kid back in the 50's, I'd routinely get zapped off metal cased radios. I learned to isolate myself instinctively and to flip the polarity around with the plug. It wasn't just radios that had this issue. I noticed it too with certain appliances like toasters and refrigerators. Amazing times back then.
My 3 S120's that I've touched up have not killed me yet:) Waiting for the Selinium to go!!;)
Selenium RectumFrier@@crosleyfiver8686
Had an old one as a kid and it used to give me a tickle all the time until I mentioned it to a local Ham G3RXH. He explained it was an All American 5 underneath and told me to get a 1:1 mains transformer from a bathroom shaver socket and put that in between the radio and the mains. He was a kind man, my Elmer. R.I.P. Howard.
They only had four tubes, 50C5, 35W4, 12AV6, and 12BE6. No RF amp, straight into the mixer. Radio had lots of images. I bought the S-meter kit for mine. My dad had a little electronics experience and after finding which blade on the power plug went to the on-off switch he marked the plug so I wouldn't get shocked.
Yeah the mains rectifier was solid state I think - no tube@@spaceflight1019
i built that Knight Star Roamer when i was 12....still have it,,, did have to recap it last year ,,
I love the Star Roamer look and feel. What kid wouldn't!
Some of these older receivers don't even have a fuse, let alone polarized power cables, wonder how many folks back in the day would actually gotten zapped! I just uploaded a video where i installed a fuse and a polarized cable on a Hallicrafters. Thanks for the info!
Well back then folks listened to the radios. They were new and usually needed no "touching" in the nether parts.
These are all great comments! I acknowledge that some folks are unable to accept the level of risk associated with AC/DC sets or having a handgun in the house, or owning a pool, or flying, or a dog, no matter the measures taken. And it's not personal. Most of us hams consider the novice or untrained and what might happen to that kid as the worst case. Insurance companies have to consider the general public and completely untrained against any benefit to the manufacturers or the public, and make a guess as to a level of safety that is acceptable. So even if there is some safety level associated with say - the Specific Absorption Rate of RF against your head with your mobile phone, and it is tested in a lab, some still may not be comfortable with it. That's Normal.
Thanks for the trip down memory lane. My dad gave me one in the mid 60's and I had it until the 80's. It got me on my way to getting my ham ticket. I loved that radio.
Now that I have been playing with a couple lately, I can see why. But it has some warts too!
I recapped my Hallicrafters S-120 and made a 2-part video here on UA-cam (Jan 2021). As I recall, it was a nightmare to work on. I had to rely on 2 parts radios. One was a Lafayette HE-40. Almost identical, except it also had an S-Meter. Even after the recap, I had to work on reducing the hum. I sold it at NEAR-Fest soon after. It went to a good home.
It was nice to see you there at NEAR-Fest. I think I saw this radio on your table, and we talked about it.
73 Paul AA1SU
They are a tricky radio to get the hum out of. And less hum with one plug direction that puts neutral closest to the chassis ground.
More common than the shortwave radios were the two wire, non-polarized "All American Five" AM radios, such as the clock-radios found in kitchens all around the country during the 60's. Somehow most of us survived.
The advantage with these table radios was that we were not attaching stuff like antennas and ground, headphones, tape recorders, and so on. Plus, everything was insulated, even the knobs.
@@MIKROWAVE1 Almost - My Emerson 547 was fine as long as 1. You used the supplied knobs. 2 Didn't try to hook up an external antenna, and 3. DIDN"T TOUCH the screws on the bottom of the radio. I found that out when I was about 14. Many years ago now.
@@jrkorman i have one of those, not common to find them or any american set here in the uk, also have a few others, most use a 'semi isolated' chassis , with chassis isolated from direct connection to circuit negative via a cap and resistor, but this emerson isnt! dunno why they didnt do it as knobs come off very easily exposing live spindles, plus those live screws on the bottom! UK and europe made/designed acdc sets had to use good safety practices as our mains is double the US but strangely almost never used the capacitor isolated chassis idea apart from 3 models i know of, i have 2 of them
Ya - notice those radios were encased in a Bakelite case and the knobs were also insulated too! I'm from that era and remember those 'hot' chassis too.
Hey! Former Project Manager at U.L. in the early 2000s, specifically in Wire & Cable but I also mingled in all other fields too. Companies don't submit reports to be certified. They send in a sample of their product and then it is thoroughly tested by the engineers. For instance, in W&C, there would be burn tests, crush tests and the like. In plain English, if stuff didn't burn more than it was supposed to, or break down with less force than was reasonable, then it got the seal of approval. There is always a battery of tests suitable for the field the product falls into. Basically, U.L. makes the report and not the submitting company. Rock on.
Thanks for this Chris! I have never been through a UL process, but one company I worked for did submit FM (Factory Mutual) for some products. I was doing FCC Type Certs and Military and FAA Aircraft lab testing and submissions regularly in various companies. So what you are saying is that Hallicrafters would have had to send a sample radio in for testing in the lab, especially in 1960...
@@MIKROWAVE1 Yes, I think it is highly likely that even then in 1960 era that a sample was sent in. You're most certainly welcome. That's cool!
Across your hand even without the network the 120v wouldn't kill you. You would get enough of a shock to violently jerk your hand away, and that could injure you. However, if you touched the "hot" ground with your hand, but your other hand was grounded, now you have a current path that goes through your trunk, which could shock your heart and cause cardiac arrest. The current required for that is just a few tens of MA. Wet your hands in brime and then measure your skin resistance. It could be less than 1000 ohms! Sweat will do that too!
BTW, while Knight Kit designed the Star Romer with 6.3 volt tubes and a power transformer, Heathkit had several models that used the standard All American 5 tube set, BUT they had a 1:1 isolation transformer in the power supply.
All great information. Yes the kit folks just did not want to take a chance. They generally used isolation transformers.
If you don't have an isulation transformer. You can make your own by connecting a filament transformer to another one in reverse connect the two filament sides together and use the two primaries to hook up the radio. Make sure the secondaries are in phase with each other. Use a scope then you don't have to open up the transformer. I'm sure the net has the know how. 73
I feel fortunate that I survived my experience of learning about AC/DC sets early on when I started restoring antique radios. I lovingly refer to my 1950 Silvertone Model 2 as the "little radio of death" since it has a metal case that had a 50% chance of being electrically hot even when it was turned off. While holding onto the PL-259 end of my amateur radio antenna (which was grounded), I leaned on top of that radio with my elbow by mistake. I put a polarized plug on it after my arm stopped tingling.
Yes there really were seriously unprotected circuits in those days with little to protect but a cheater cord on the panel and plastic knobs.
Early on in my radio days I was told to keep one hand in my pocket if i am working on a live circuit. That probably saved my life more than once when I was a teenager
I got hit really bad twice as a teen on shiny ungrounded hand drills - both were 120VAC. The 500 to 700V DC hits on my early power supplies for ham stuff Hurt and Zap, but not as bad as the through the body 120.
I used to have a Hallicrafters S-86 half a life time (15 years) ago. There are a few videos of it way down on my UA-cam channel. The first time i was gonna test it, i almost touched the case. I knew it was an AC/DC set, but all Philips ac/dc sets are completely safe and well engineered so i thought 'Eh, it'll be fine'. But a little voice nagged and made me measure for voltage, and there was the full 230v mains on the case.
After recapping the thing, the short was still there. I never got around to actually finding that short. For a couple of weeks i used it like that, just measuring the voltage each time, but shortly aftermaking the video on my channel i hardwired a 230v-110v isolation transformer into mains cord, and ripped out the 220v-110v autotransformer.
I eventually sold it to a friend who knows his way around mains safety, explicitely notifying him of the issue.
So yeah, those Hallicrafters things are pretty dangerous. Incomparable to the Philips AC/DC sets i'm used to.
230V is more challenging but that did not dissuade Euro manufacturers from trying AC/DC to save some $. The autotransformer idea is interesting - and scary!
@@MIKROWAVE1 philps acdc sets are 'usually' very safe designed, but in this case maybe some previous 'engineer' /owner has done a 'bodge' ruining safety
@@andygozzo72 Ah a conversion Artist of days gone by. Yes.
I'd like to see how to properly rewire an old piece of gear for a modern 3 prong plug. Many sites will just say "Of course I rewired the radio to a modern plug.." But do not show what is done safely....
There are more important issues with such old stuff that you gotta fix before rewiring the plug - you gotta verify that the PSU electrolytics are not electrically leaky, and replace at least a couple of the wax paper capacitors.
With that i mean that if you rewire the mains cable - which is a good idea in itself - and start using it, you'll likely blow stuff up that's worn out from being over 60 years old.
But the basic concept is simple: get a vintage looking but modern cable and plug. Live to live, neutral to neutral, earth connected to a heavy duty solder lug that you put under an existing nut and bolt connection on the chassis.
@@mfbfreak All great advice. Some older sets simply do not have separate power ground but use chassis for everything. These are real widowmakers that require true isolation because you can not use the 3 wire plug idea unless you lift everything off chassis and make a separate ground bus. It go Boom. The best you can do is to use a new polarized cord and guarantee that the outlet is wired right - and test it. Still dangerous. For table radios with plastic cases and knobs this worked. But with Ham gear where you attach stuff like antennas and headphones, Keys and a Ground wire - trouble.
Excellent video with great explanations Mike. Safety first !
I survived so all good!
My uncle had the Halicrafters S120. He used to listen to the old country (Radio Netherlands). I would love to pick one of these up.
The end of an era with so many shortwave stations going silent. Oh but I do have good news. When I was in the old country on vacation in Amsterdam- I noticed that they seem to have many new women riding bicycles!
In the 1980s I used my Hallicrafters sw 500 to listen to cordless phones around 1.7mhz,
I used to reverse the plug in the wall socket and the radio would oscillate,
and It would jamm the cordless phones.
for a 1/2 mile radius.😄
The Horror!
@@MIKROWAVE1 You could hear people on their phones saying"what is that noise?" Thank god they were Engineered and UL approved. :)
Though everything you said is true, I would still treat that type of technology like a hand weapon. It is always loaded even when it isn't. That safety capacitor could experience a freak isolation breakdown. A small piece of detritus could dislodge inside the chassis and short something. An insect could carbonize between to points of high potential. Highly unlikely? Certainly. But, unless it is transformer isolated, I would consider it risky at best. In my own defense, I love these old radios. I am simply preaching caution. You only have to be wrong once. Then it's too late.
*Word.*
I've experienced the insect carbonization. Might be rare, but not for me. I would at least put a polarized plug on that rig.
@@Homer19521 even better, fit a 3 core mains lead and earth the outer case
I was given a Hallicrafters as a child, too young to appreciate what it was. I don't even know what happened to it. All older electronics were not built to the same standard as new ones. Safety capacitors Y or X types had not been invented and metal chassis were often powered by one side of the line. Used to listen to Hawaii radio from Los Angeles.
Never trust old electronics the way you might trust quality new equipment, which includes things as minor as using it with bare feet on a tile floor. C30 should be a Y-rated capacitor.
I would love to have that radio now.
The current advice goes a bit beyond just restoration with new caps. So much else has aged.
Reminds me of playing through an old guitar amplifier. "Hey, it tickles!" All fun and games until you touch your lips to a microphone and wind up laying on the floor seeing stars, or worse maybe seeing your maker.
For some singers this could work. R_E_S_P_E_C_T
Back in highdchool on the late 60s everything i built was tube & powered directly off the 117V AC line...receivers, AM transmitters, guitar amps for my brother's rock band
Although dangerous during certain conditions and component failures, this was indeed considered as "acceptable risk" during that time period. It still is in many appliances. Hence the UL approval.
Great information. This goes for any AA5 receiver on knowing it's limitations and how to improve the situation to make
these radios safe as posible. Thanks for making this video Mike. Steve
many seem to use capacitor isolated chassis, i have a few, uncommon here in the uk, and less an issue with plastic or wood cabinets, but still have to watch out for control spindles and external connections, our mains is double the US but the capacitor isolated chassis idea was surprisingly almost never used
They also insulated Chassis from Metal Case and float the Phone jack after the speaker secondary. So pretty good.
My S-120 never tried to kill me, but I was shocked (literally and physically) as a 14 year old when my S-38 tried to bite me! My S-19R with onboard isolating transformer has always been a peaceable Sky Buddy of radio😃- DE K1TB
I got hold of an old Sky Buddy, did a basic restore and sold it off. What a great old box!
Valve (tube) tv sets in the UK were non-isolated and remember that's at 240 volts, fine to fix in the workshop with an isolated bench supply, but you had to be very careful in customers homes. I remember at one house, every time I unplugged the set, the customer who I suspect was suffering from early dementia, plugged it back in. I only noticed because the filaments started to glow.
I also remember on numerous occasions, having to quickly grab the arm of an enquiring customer as it delved into the back of their live set. Luckily I didn't do that job for long, I don't think that my nerves would have held out.
Steve
Wow. If it makes you feel any better. I think 50Hz is safer than 60 Hz. Hee.
I typically use a polarized 3 wire plug. Connecting the green safety ground to exposed metal parts when possible. If the chassis is “hot” , I connect the neutral (white, current carrying conductor) to the chassis. This can put the line side 120 v on the antennae as shown in-the video. The best way is to always
use an isolation transformer.
A safety ground is only supposed to be active in case of a ground fault, normally never carry current.
The white neutral always carries return current.
Neutral and safety ground return to the same point, but the safety ground is typically less resistance and shorter path to ground.
It would seem like a good idea to put a high value resistance on the antenna connection to the tuning coil, and also between the low side of the coil and ground. Current surges on the neutral bus, and high static charges on the antenna can burn out the tuning coils.
@@ebones6957 This happened to me with a small surplus R-508 aircraft receiver That I did a back of set AC/DC supply for. It had a 24V transformer and a simple voltage doubler off the line. Very clever and very dangerous - and published in some old article. Well you guessed it, The cassis was hot and the little antenna touched ground. Pop! there went the front end coils.
Very well done. I have several radios I plan to restore. Good reminder to check little things.
Thanks for watching!
I still have my s-120 I purchased used from a pawn shop back in the 1979’s. Paid way too much for it. Generally a nice SWL receiver and a touchy ham receiver.
The BFO circuit when it works, is cute and touchy and that is being nice!
Yea I had this problem with my first radio, the SX-99, back in 1957.
Oh, so now I get some of the tingles I've felt before. But then the last time I felt it on my battery charger (transformer type). I'm learning. 73
That'll probably just be capacitive coupling and not 'hard' mains. Get an isolation tester, or hook it up to a GFCI outlet and give it a ground lead.
@@mfbfreak It works, so I don't fret over it. Thanks. Too many other things to get done. Those other times were on equipment decades ago. I never quite "got" the polarity of A/C, but now I do.
Personally, I would make it a 3-wire cord and not rely on the polarized plug, which is easily reversed using a worn-out extension-cord!
I really think that it was a huge-mistake to make any ham-equipment line-operated since there is much more chances of both the 'novice' getting inside it and various hook-ups that might be made while experimenting with antennas and such.
Finally, the immediate danger of hooking test-equipment to the receiver and depending on that person either having an isolation xfmr (ha-ha back then!) or automatically knowing to check the potential difference beforehand! 73...
Edit: There is another reason I feel this is bad: The first time someone without knowledge of this phenomena gets a 'tingle', the radio is probably going in the trash can or will at-best become a shelf queen!
What was the purpose of the word, personally?
@@K1OIK my preference
@@SpinStar1956 yep, i would probably fit a 3 core mains lead in this circumstance, some UK sets, eg. eddystone 840C used this idea, inner chassis was 'live' but isolated from the earthed outer case by plastic standoffs
@@SpinStar1956 I like to add useless words?
I once owned a Hallicrafters S-120. It has what is known as a "hot" chassis. Plug it in the wrong way and you got zapped. My Mom and Dad owned a Muntz tv way back in the day also. That television also had a hot chassis. I remember very well getting shocked by that thing.
Muntz is a great story. He would sneak into the lab and cut the parts out that the engineers would put in to any new chassis and see if the set would still work in the big signal metropolitan NY area. If it did, the parts stayed out. That was how he reduced costs to make a super cheap set!
Excellent illustration of early line isolation. I might mention the show and tell part of would you feel this; the completed circuit path was between two fingers on the same hand; Old timers voltage tester. May be a little more noticeable if it passed through your body with your heart in the path. Also pre GFCI days threshold of 30 ma. I can understand not wanting to complicate the issue. Thanks for a easy to understand video.
My worst truly close calls were from an old very shiny Drill a guy gave me as a kid.
I liked it. I have a eico signal generator that I replaced the 2 line to chassis cap with safety caps and left them in. It'll tickle you a bit, but it's not going to hurt anyone, plus I didn't want a second ground path when using it.
Some people have no risk tolerance.
Yes same type of circuit but no attempt to isolate the case physically. Only the resistor and cap treatment.
I have 2 S-120's. 1 for parts. The other for posterity on my shelf. Not that great a receiver, but hey, I have one! And the 50C5 runs smok'n hot!!
---
Wanted to send you an email about some MOD's, but you don't allow them, so that's that.
Original is great and that has its place in our hobby, but I live on MODS that improve performance and are reversible or provide a logical safety advantage. Seriously nothing I touch is original museum quality stuff. In fact I like to buy broken stuff. I only get nervous when someone says "it works perfectly".
@@MIKROWAVE1 - I also do prefer to keep it original, but one of these mods gets rid of the Selenium Rectifier, the other improves on the crappy BFO!
@tubeDude48 both are worthwhile improvements without destroying the set, in my opinion. Now, I might draw the line at drilling a hole on the rear chassis for a fuseholder, but I would go for an internal fuseholder using an existing screwhole.
@@MIKROWAVE1 - I agree!
Modern stuff is built the same way, DVD players, phone chargers, etc. Every two wire swithing power supply, any metal case two wire electronic device. Some stuff like the phone chargers are even unpolarized, you don't get bit because you usually aren't earthed all that well. The only difference is they use safety caps and fairly high voltage resistors.
Most of the modern switcher wall warts have a high frequency transformer that has isolation enough to be approved.
I still have mine. I got a nasty shock from it the last time i used it. I guess I need to put that kit in it. I broke 4 vertebrae in my back, so I have plenty of time on my hands to fix it.
I like how a radio gives you clues about its needs - you know like smoke signals and attention getting troubleshooting aids!
there was some UK Eddystone models that used 'live' circuitry, the inner chassis was common circuit negstive and connected to one pole of the mains but the outer metal cabinet was isolated from it with plastic spacers and standoffs, potentiometers and controls had their own plastic grommets, AND it was also earthed to mains earth, it had a 3 core mains lead, BUT the plastic insulation and spacing was good enough if you had to use it with a 2 core supply for some reason,
It turns out to be a lot of work to have true isolation that way!
Back when I was a young teen just getting into working on radios, I quickly learned to reverse the plug in order to not feel the tingling or a shock, when touching the chassis or any exposed metal parts. Never made any sense to why direct ac-dc line powered radios were made, by the 1960's how many utilities still served any customers with 105-125 volts DC? These kind are bare minimum sets, just enough parts to have mediocre performance in most designs.
Dunno maybe Canada still had DC Towns? ;)
Wow - How did you know? Recently picked up an S-120 and before even touching the thing I downloaded the schematic and identified the exact points that you showed in this video. Thanks for the heads up on the recap kit.
There are a lot of them out there!
Chassis is hot put it on the isolation transformer
For bench testing AC/DC stuff or any exposed 120 work I have a GFCI outlet in a box with a short power cord, not something you should be tripping often (tests aside) but it will protect you from any real current flowing from live to anywhere except neutral if you screw up.
GFCI are great in properly wired houses and this is a great idea. You would be surprised how many old houses are hay wired and with no ground in sight!
S120 had a hot chassis which cost me money years ago when I had to add an audio amp that was hot chassis also. The receiver was not legally UL approved to even be earth grounded for the antenna. Ended up trading it to a fellow CB/Shortwave listener that used headphones. Lol
Well now you are talking. Getting two widowmakers to interface without trouble. This is where you need your Handi-Tester or a Meter, which of course we never had or had time for...
I have been bitten by that radio many times but not since I was 15 years old - No transformer at all as I recall and series filaments. Ultimate cost cutting back then. This radio did not have an RF amplifier either.
Nor the all important RF Gain Control or good AGC on CW and SSB. It really was an AM Shortwave radio.
I remember when I was a kid probably 4 or 5 or so I can't exactly remember when but I remember plugging in a clock and my finger got caught between the plastic part of the plug and it was touching the metal prong and oh boy I sure as hell felt that shock it felt like my body was buzzing and it didn't feel like a tickle to me but then again I was a little kid so I felt it more and ever since then I've been super careful when I work on electrical stuff.
Those who have been hit a few times generally have a hand in the back pocket as a habit which means a memory is imprinted!
As a 22 year old, I built a Philmore ac/dc 3 tube Regen rcvr It was open and dangerous!!!! I got shocked several of times with it's open metal chassis! Hi one stupid!
Oh yes! and the Meissner Kits too!
never bought a Meissner kit, Heathkits, Arkay, Kinght . I later went on to become an EE@@MIKROWAVE1
Interesting how our two countries differed in their thinking on electrical safety. The UK had a 3 pin plug system which prevented reverse polarity and had an earth wire from an early time...BUT they were running at 240V AC and now have dropped it down to 220-230V AC to conform to European standards. 230V shocks are not funny!
It was the same for us in Australia we had polarized plugs as well with an earth pin as well and power @ 240V 50 Hz. and yes 240 V really bites hard.
@@steviebboy69 Thanks for your comment Steve. What is the voltage in Australia today and is it the same in all states? I'm guessing it might be similar to the European model? 73 Ace
@@acestudioscouk-Ace-G0ACE Here in my state of Victoria it is normally around 240, but I have seen it sag to around 220 in summer. I am sure I read over in the west it is or was 260 V. I am sure those big chunky UK plugs hurt more to stand on by the way.
@@steviebboy69 You are dead right, standing on a UK plug hurts more than standing on kids Lego!!
It's still 240 V in the UK and 220 V in continental Europe. It's just that the European standard changed to a nominal 230 V to take account of both.
I am not surprised that the Hallicrafters is better than the Knight (all else being equal). Hallicrafters seems to be especially good for squeezing performance out of budget builds. I am not entirely sure how they pulled it off sometimes, better inductors maybe? I did a Hallicrafters "Continental" for a friend (just a plastic AA5 set) and well, who hasn't done a few mass produced AA5s from the 1950s at some point or another? The Hallicrafters would beat the pants out of all of them in performance AM broadcast dx'ing, yet utilized the same tube lineup to do so. Imagine what they could have done if they'd had more "cost is no object" models and catered to high end ham or military markets.
You are right that it does not make sense with so few stages. Up until Band 4, the radio actually has too much gain!
I got given a Texas star for cb had some mods and it would burn my truck , crazy as it sounds, it’s old 86 Nissan 4x4 but it burnt my reg cd radio above it out the heater connection behind, I key up in beginning it would shut lights off at night but capacitors where grounded to the outside of box when took it apart, I had it redone nothing burnt so far , lights still dim but it talks to Maine from TN
That thing is dangerous to small electronics it is near!
Hallicrafter bit my lip often! Lit me up like a electric fence!
Why the big difference in audio, starting at around 2:33 ? I kinda like the first style, for what its worth.
Because I am not set up for decent audio! But I do go for intelligibility at least! I use the camera mic, an old Hand Dynamic sometimes with the camera, and a Boom Electret for annotation on the slides, which you are hearing. They all sound completely different.
"Widow-maker receiver" 😂
It is the latest of the widowmakers, with two levels of protection. Chassis to neutral network and isolated Chassis to Case. So pretty well done.
Just plug in isolation transformer if you are servicing. Real issue is that mains noise feeds back into the antenna as there is no isolation transformer in these which isolate the noise also
With an isolation transformer in place, generally the station ground can be applied to the ground terminal and noise will reduce now that you have a reference. But most importantly, the Case and Chassis become safe if you get between it and ground.
What are we going to do tonight, Brain? What we always do, Pinky, we're gonna take over the world! muahhahaha.
Can you make the S-120 shower safe? I feel asleep halfway through. Why do you recap? Do you replace your teeth just because they are old?
*lol*
Nobody in my neighborhood has a shower, and its only a risk once a week anyway.
So, when the dentist says "we need to replace your old mercury fillings by new ceramic implants", you say "No"! Really?
I don't see the problem in replacing anything that is old and wrong.
@@alainmichaud8992 Why would I replace fillings that are not bothering me? You think implants are free?
IIRC, the UL rating isnt so much about the electrical safety of the product, as it certifies the product doesnt present a fire hazard,. Adding a polarized Line cord is a big improvement in safety. I believe CSA(Canadian safety organization) required polarized cord long before they became common in the US.
U.L. has tests for all categories of products they certify. Safety is a top priority in all categories.
Aviation moved to VHF FM decades ago.
Well VHF AM actually. The Brits came up with the SCR-522 AM Transmitter Receiver and sent the plans over to the USA and we manufactured thousands of them for the fighters. Aircraft went VHF AM quickly after the war except for overseas which to this day still uses SSB on HF. They are starting to deploy NEXTGEN which should start to make digital inroads soon.
I had the S120 and like most of the radios of the day it had the 0.1 Mfd death cap
You have a point. Since 120VAC is AC, the larger the cap, the more that the Chassis is connected to the outer case. But a 0.1 uF cap itself will limit the current. Its only when that cap leaks or shorts - that trouble starts! Hence the Y capacitors that FAIL OPEN.
@@MIKROWAVE1 thats why they call it the death cap, when I do any restorations I replace the cord with a polarized one, if I was to do one of these today I would most likely put a grounded plug on it
S120 is good i have 2 of them
Why not find a spot to mount a 1:1 isolation transformer and be safe no matter how the receiver is plugged in? That is how I have built my bench power supply (a variac, isolation transformer, incandescent bulb and outlet.).
Many shops do this as a matter of course. Some even go as far as putting one inside the cabinet.
My uncle had an S-120 in the Army in Germany. Deaf on 10M.
Imho; The upper bands were poor on most general coverage receivers. Higher frequencies require a narrower front end.
An external converter that took 10m down to the 80M range would be a possible approach. This would be dual conversion and add gain and lower noise figure, too. Typically, this could be done with a 6BZ6 and 6U8 and a crystal.
If you are building a kit you should know the dangers of tube receivers transformer or no transformer. I built a greymark 2 band radio and there was no isolation transformer. Common sense would tell you to take a neon test probe and make sure the chassis is not hot. My first TV had a polarized plug and my Uncle shaved off the neutral side of the plug so the TV could be plugged in an extension cord. I always looked where the neutral is before pluging it in. Some say about headphones but the output already has a transformer so whats the problem just dont mount the jack on the metal part of the radio mount it on the plastic case. These are safety measures you can take to protect against shock. I have one of those radios and i would first check polarity of the line cord. Thats what a multi meter is for. If you are not smart with electricity dont modify a radio. 73
The old cheater cord trick. How was your Uncle supposed to pull and wiggle tubes without his cheater cord? Hee.
@@MIKROWAVE1 he never messed with the TV just the line cord. I never wiggled anything just remove tubes and take them to radio shack and test them if there was a bad one they could order one. and that tube was replaced for free if it ever quit working. Radio Shack had lifetime warranty on all their tubes they were expensive so you paid for free replacement so it really wasn't free. 73
I've never met a person who had been killed by electric shock.
Good stories though. I knew A guy who could not let go of an Apache HV 750V but he fell and the weight released his hand. All good but the radio followed and smashed him.
Measuring voltage on the chassis with a 10Meg ohm meter doesn’t really tell anything useful. You need to shunt the meter with a reasonable resistance to really make any read of leakage
Excellent point and and yes a lower Z meter like a Simpson would have read less voltage of course, especially on the outer case which has some isolation. That was one reason I included the 10K resistor tests.
I am kind of intrigued by the comments and the perspective of the video.
The UL standard may have changed since 1960? Doesn't "dual-insulation" require a thick plastic case? Is the 3-pin plug really acceptable as a polarizing plug? Can a "dual-insulation" equipment be fitted with extra connectors such as "earphones" or "antenna"? If I were a young radio enthusiast, one thing I would like to do is to connect the speaker output to my computer audio input?
How difficult would that be to retrofit the instrument with a properly insulated power supply or transformer? The real thing! Why not?
Walworth adapters are intrinsically safe. It does not come to mind easily to young people who never knew anything else that mains outlets are dangerous. Even less with high DC voltage.
Voila. My two cent. Tube electronics really scares me...
no you can have double/dual insulated devices with metal cases, such as vcrs, digiboxes, etc. , there must be minimum clearances between live parts and the metal case, and 'double insulation' within parts like mains transformers, eg. having a split bobbin, mains on one ,low voltage secondary on the other
The Hallicrafters took extra care to isolate both the Antenna input and Headphone output and Speaker from Chassis. Case is deliberately isolated from Chassis (within reason and "safe" levels). Most AC/DC radios did no go that far. Hook something up and bad things could happen.
Undertakers Laboratories
Selenium Rectumfrier!
@@MIKROWAVE1 I burned up a selenium rectifier when I was a young teen. Never forgot the stench
Nice content! Wondering if any custom PCBs may help for any upcoming radio projects? If so, would love to supply and reach any collab together if there's a chance! 🤗(PCBWay zoey)
The tedium of doing the parts library is significant. But yes I am heading towards some simple PCB kits to give away to patrons. Like a Paraset circuit in Solid State and in Valve for instance.
@@MIKROWAVE1 Good to know. Any interest to have a further talk? My contact info is available under this account, looking forward to hearing from you.
Yikes.
The S120 will zap the hell out of you if you plug it in wrong yikes
As they AGE. The Halli S-120 has double protection. It is a late model AC/DC and they sent it in for UL testing. Protection 1 was separation of Chassis from Neutral (or Hot if plugged in wrong) with proscribed 470K and 0.047 uF 600V cap. and 2. They went as far as isolating Chassis from Case mechanically. And even isolated the Phone Jack with shoulder washers floating the secondary of the speaker transformer. So nowhere near the killer of the typical 40's AC/DC.