Protecting your antique tube radios

[@zx8401ztv]

Yep it's a good protection for old valve receivers, but i don't think the spider that came down the inside of the case was too happy lol. Valves/Tubes have always been a forgiving component, i've found sets full of carbon resistors that have gone really high due to heat and the radio still works.

[@jukeman57]

Good idea. Beautiful old radio. I can only imagine the many families sitting around listening to it over the years.

[@markpirateuk]

I certainly agree with adding protection, my vintage sets are retro fitted with suitably rated fuses under the chassis. Being in the UK, I also fit a suitable fuse in the plug.

[@madbitvanner9107]

Wow. Loved your video. Some commented about not space in smaller cabinets. In those cases I would simply modify a desk lamp to have an outlet for the radio. Thanks for the video!

[@timmack2415]

I've done this to a few of my console radios here in the US. My line voltage is around 128 VAC and the light bulbs drop that to a better level too.

[@rondeldebbio9219]

Great idea.

[@ericklassen742]

Smart! Have you tried using an inductive load for protection to save having a ligt shining against the wall when radio is ON? Maybe a couple of FL ballasts, etc.

[@michvod]

There are few problems with that. You can't just install dim bulbs in 95% of the radios as there is simply not enough space. Also the originality is ruined, perhaps it is a mint radio and you just damaged the wood by screwing the bulb holder into it. I do it like this: 1. replace all the usual components (paper capacitors, electrolytic capacitors, etc.). This is just common sense and a lot of the times the radio won't even work without recap. 2. use a low amp fuse. 3. (optional) install a dropping resistor to knock the voltage down a bit - being from 230V country, I usually install 22-47ohms in series with primary to drop about 10-12V to the original 220V that old devices are specced at. 4. (for being extra cautious) fuse everything - heaters, B+ line, output tube plate line, etc. I have an old German Saba radio that has all those fuses and I doubt the power transformer will ever go out no matter what happens to that radio :)

[@michvod]

Also a lot of the times the dim bulb will just knock the voltage too much, I have a set that is specced 45W and with 100W bulb in series it will barely work, FM will not work at all. Some also say that tube heaters don't like to be under-run too much, which might be the case with the dim bulb.

[@12voltvids]

Dim bulb of sufficient wattage won't drop the voltage that much. As to attaching inside a large cabinet not a problem. The wood inside is not finished anyway. Fusing only works if the fuse blows. You can be into a current run away and the power supply is not drawing enough to blow the fuse. Remember fuse needs to be large enough as to not blow at turn on when tubes are cold. A fuse that is big enough not to nuisance trip is probably too large for safety. For portable radios I have a cord set with a lamp on it in series. Never have had any issues. I don't listen to these old dinosaurs regularly though. They are mostly for show and I turn them on once in awhile. Don't want to consume obsolete tubes.

[@michvod]

​@@12voltvids Sure, no worries. A lamp of a too large wattage might not prevent damage after all. I had an arcing tube socket in one of my radios that I dim bulbed it, and it nicely smoked a lot and opened the plate resistor, despite having a 120W bulb in series and being a 60W set. Years ago I plugged in an old radio for testing purposes (I didn't have a dim bulb then), and it immediately blew the fuse. I then bypassed the fuse and hooked it up to a wattmeter, and it showed almost 750W draw (I had it on for 2 seconds). Next I found the rectifier has cracked and transformer secondary shorted to ground.

[@12voltvids]

@@michvod That's why you don't use too large of lamp. Nothing is fool proof but having a lamp in series will greatly reduce the change of damage and more importantly the chance of one of these old beasts bursting into flames. Saying that, NEVER leave one of these things plugged in if you leave the room. These old radios, restored or nor are decorations and should not be used as daily drivers. They are nice to look at, and demo for people but they should never be trusted. Back when they were new they caused a number of house fires and they haven't gotten any safer as time passed.

[@pitsnake]

You can also use a quick responding fuse if you know what limit the transformers can, light bulb is good solution when troubleshooting on repair

[@tvtech2582]

I heard you say dim bulb and I thought you were making a Chinese Dish !

[@ericklassen742]

Have you ever noticed that it's the good YT chnnels that reply to their commenters?

[@12voltvids]

Harder now because the KZbin app no longer runs on my old phone. Can't reply to anything. Locks the phone up and forces reboot. Old phone and I'm not upgrading as they took away microsd card. So I have to do it with yt studio. Hopefully when they force an upgrade they validate that it works with Android 10. If KZbin stops allowing uploads from win7 i guess my channel will go away.

[@GeorgeChristofi]

And sometimes, the dim bulb will stop it working. Also, putting a bulb inside a cabinet could create heat inside. Better off just fitting a fuseholder and fuse. Make it internal to the chassis so if it blows, it needs to come back to find the cause.

[@12voltvids]

Negative. Dim bulb will have no effect on performance. If I put in a 40 or 60 watt, then yes it would cause the B+ to be too low, which would result in distorted low audio, and affect the sensitivity, but a 100 watt bulb, or 2 60's in parallel will provide more than enough voltage. I bet if I measured the B+ it would still be up in the 400V range. You need to go higher than the maximum consumption. A 100 or 2 60's in parallel will have more than enough power to run the unit. As far as heat goes, the bulb is just warm to the touch. I can grab the bulb after it running for hours. A fuse may blow for no reason if there is an intermittent over current such as turn on, when the tube filaments are cold. They draw a shitload of current when they are cold for that first few seconds. Also having a light bulb in series gives it a "soft" start. Any way you look at it, this is the safest option to protect vintage electronics. Old tube televisions used to use time delay fuses, or circuit breakers to prevent nuisance trips due to surges and momentarily over current. The problem with slo blow fuses and circuit breakers is if something does happen, the damage can extend far beyond the original fault by the time the breaker trips, or the slow blow fuse heats up hot enough to melt the connection and open the circuit. This dispenses with all that. Enough current get to the unit to operate it, and excessive current is prevented. A dead short will just make the light glow full brightness. There will still not be a hazard, because it is in a UL light fixture, designed for wall or ceiling mounting. The bulb is isolated far enough away from any combustibles.

[@GeorgeChristofi]

yep, agree with most of that but if I was going to do it then nothing wrong with using a MOV and a fuse if I was going to add extra protection. The biggest problem is getting any tungsten lamp of a high enough wattage into most cases. Certainly wouldn't get one in the 1949 Ace 50 tabletop I'm restoring at the moment.

[@12voltvids]

Also, consider this. Prior to 1970's the voltage in north america was 110/220. It initially started out that way because the original light bulbs required about 100 volts to be bright enough, so to ensure that 100 volts was available the voltage was set up to 110. In the late 50's this was increased to 115, and in 1968 the standard was set at 120/240 and most utilities had adjusted to the new standard by the early 70's. This old radio is designed for power systems 105-125 volts. This is because the voltage fluctuated widely back in the early days, depending on how far you were from the generating station. I measured it, and with 120 volts input, the power making it through the 100 watt lighht bulb is actually 102 volts, which is well within the operating range if it was originally running on a 110 supply during brownout conditions, where the voltage could drop substantially. An MOV is not going to do anything to protect these old devices. They typically don't conduct until well over 200 volts and all a MOV s going to do is trip your fuse on a brief power surge that is not going to harm one of these anyway, because tubes are very forgiving to overload. What a dim bulb will do is regulate the flow of current, as when the filament warms the resistance will go up, so it will regulate the flow of current and keep it at a totally safe level. The electricians and engineers watching this fully understand this principle. It is the simplest way to protect equipment. This won't work on equipment that is voltage sensitive, however with old tube gear this is not the case. It is much simpler, and far more reliable than other methods of protection, gives that natural soft start, which protects the tubes from that initial shock of starting cold, and the bulb running on very low current is never going to burn out.

[@GeorgeChristofi]

I understand the principle, I use dim bulbs all the time when testing stuff. The reason I was looking at MOVs was the UK standard rms voltage of 240v, we peak at 300 ish... I have measured spikes here at around 500v. I'm not arguing that the dim bulb is the simplest solution but it isn't the sort of thing that fits in with the sort of vintage radios we have in the UK. There wouldn't have been room for anything like that in my Eddystone 840a, Ferranti 1016 or even the one I'm doing at the moment! I'd hazard a guess that you would be pushed to fit a torch bulb into the likes of a Bush DAC90! In fact, thinking back, the Eddystone used a varistor for the purpouse of inrush regulation and spike prevention. Same principle, temperature changes resistance without the visual indicator that the tungsten bulb has. The Eddystone was also an AC/DC world set so there was no mains transformer, just the big resistor tapped at intervals for varying voltages. Keep the videos coming, I look forward to watching your stuff because it is more interesting than a lot of others out there. All the best, George

[@12voltvids]

Just did an AC/DC radio today. No transformer, all tube filaments in series. The dim bulb on the line cord only works when you have a huge cabinet like this. I don't have one on my Pye P75, but I do have a step up transformer to boost to 240V for that one, and it is limited to 100 watts, or about 800 miliamps, and it is fused. The radio and the transformer.

[@maicod]

would a fuse give the same protection ?

[@Bushougoma]

6:44 Daddy long legs doesn't like the new bulb or is camera shy :-).

[@scaleop4]

lol that's were it lives

[@1959Berre]

Why not fuses in different spots to protect different parts? The spider is moving, hates the light.

[@12voltvids]

Dim bulb will protect everything at once.

[@Bluethunderboom]

Will the Sunbeam 100 Watt incandescent bulb do same thing as an old 100 Watt bulb does? The voltage rating from Sunbeam is 130 Volts.

[@nor4277]

Great sounding tube radio,that's why I like old radios they just sound better to me ,I did a while back buy a tube radio off of good will on line ,when I got the radio,it was solid state,I don't think young people wouldn't no a tube If It bit them ,I guess if it's a older 60 ,a radio or older they must assume it has tubes ,they gave me my money back.and let me keep the radio ,mostly because the clock face was damage,I didn't even get to tell them it wasn't a tube radio either.

[@12voltvids]

Big speakers sound fantastic. You should hear my Technics SB7000s with a tube amp driving them.

[@seanvogel8067]

Don’t you have to worry about the heat of the bulb in the cabinet?

[@sincerelyyours7538]

Projector bulbs work well and are a lot smaller. Also night-light bulbs, though they may be only 25-40 watts or so. Use 3 or 4 of them in parallel. I suspect a PTC resistor would work as well but one must choose the right one carefully, and some sort of visual indicator would need to be made to show that an over-current condition is present..

[@12voltvids]

A projector bulb will pass way too much current to do any good.

[@ikonix360]

I do the typical work when I restore an antique radio. Replace all paper and electrolytic caps, replace all carbon comp resistors (may not be true for everyone, but 90% of the carbon comps I've run across over the years have been out of tolerance high), replace defective tubes, clean pots & switches and do an alignment. I also replace all parts known to eventually fail. I use my antique radios regularly and so far I've not had any issues at all. Not saying the bulb is a bad idea though. A fuse might offer better protection though as it would blow and cut all power to the radio.

[@davesanders4381]

Why not just put an inline fuse in the AC circuit under the chassis? This preserves the look of the antique radio and provides all of the protection necessary. If you want you can also add an MOV and Safety Caps to the circuti for addional protection.

[@12voltvids]

Problem with the fuse is they will allow full current up to the melting point of the fuse. So if you have a component that fails like a capacitor that starts drawing excessive current through one of the small tubes you could be drawing enough current to damage a transformer or coil but not enough to trip a mean in line fuse. And MLB will stop surges but search is really aren't an issue for vacuum equipment. And NTC will give you a soft startup but again not really an issue. Good old incandescent light bulb does the same thing it gives you over voltage protection over current protection and a form of soft start. And also gives you a visual indicator if that light bulb starts glowing bright you know that it is drying too much current. Since it's hidden inside the back of the cabinet and the cabinet is normally pushed up against the wall you're not going to see it anyway. It's just a cheap easy way that gives you 100% protection. you have to remember a radio like this is not something that is being used everyday in fact I think this radio has been turned on maybe two or three times since this video was done. It's turned on to show off to someone from time to time but it's not turned on to listen to. so if something were to break down in the time it's turned off, what I plug it in and turn it on if I see a bright light glowing in the back I know there's a fault instantly when it's turned on. Any real collector of old vintage radios is not using them. And anyone who listens to these old radios on a regular basis as their daily driver is not a collector. The reason I say that is vacuum tubes don't last forever using them slowly burns them out. it's one thing to use a vacuum tube amplifier that parts are still readily available for but these really old vintage units the parts are scarce and when you do find them they're an arm and a leg. I was looking for a 50C5 tube recently and all the pricing I could find seem to be between 40 and $50 for a common audio amplifier tube from the '60s. Real collectors collect restore and preserve old radios but they don't use them. Fire them up once in a while just to test them and to show them to friends and stuff and the rest of the time they're basically wall art.

[@stphinkle]

Is this going to reduce the radio volume by reducing the voltage going into the radio?

[@12voltvids]

Stephen Hinkle If it does I haven't noticed. This thing can still rattle the windows and I can hear it throughout the house when I turn it on.

[@isoguy.]

Top safety tip, thanks for another great vid.

[@THOMMGB]

Hi Dave, You can clean the cabinet with Gojo hand cleaner (the non pumice kind) then go over it with Howards Walnut Restore a Finish and your cabinet will look its best. I learned about that on the Antique Radio Forum. Regards, Tom

[@andygozzo72]

a 'dim bulb' in use CAN affect the radio operation, as it will drop the volts to the set slightly, if the radio has a voltage tap you can compensate for it, its not the drop in b+ that affects it but heater voltage/current, too low and emission is reduced....i've noticed it , especially with fm sets, and if the valve emission is starting to fade due to hours of use anyway, but some valves may be less critical, i always fit a mains input fuse of suitable rating as most didnt fit one from factory, and maybe even a ht secondary fuse, some makers such as philips and murphy fitted a thermal trip of some sort to the mains transformer, but it takes time to heat up and trip it!

[@andygozzo72]

i have a philips set which is a bit unusual in that it has fuses everywhere!, mains, heater, ht feeds to each EL84, and i think overall ht fuse as well !

[@countryhamop4580]

How about just putting a miniature lamp in the center tap of the HV winding? Find one that's rated for about the same current as the transformer is rated for and it'll blow if there's an overload. That was a retrofit that had to be done to some larger Zenith sets when they overlooked the H-K breakdown ratings Of the 6X5 rectifiers in the design phase. Lots of smoked transformers when those babies shorted.

[@ikonix360]

That would work, but would only protect the HV winding.

[@EddieJazzFan]

6:44 KZbin's copyright rules for spider apearences are similar to "Beatles".....

[@12voltvids]

Spiders from mars.

[@UDX-21]

Great information, thank you. 21S.C.

[@MrVintageRestoration]

Solid advice!

[@tommyn.j3628]

That looks good 👍👍

[@danielt.8573]

Any new interference in the reception?

[@reginaldlawrence412]

Great idea I like your video.

[@12voltvids]

reginald lawrence Yes when there is room inside. Never hurts to add protection, and for old tube gear this better than any fuse as it will prevent the overload condition and give a soft start. I am probably going to modify that old Rogers radio I picked up to add some protection for the tubes on it too. I am thinking a solid state rectifier. That we give me a full wave rectifier as opposed to the 35w4 which is only half wave.

[@nor4277]

Incadesance bulbs harder to find ,I take it you can't use L.E.D. Bulbs ,I have a question I been wanting to ask you for a long time ,have you ever replaced a ferrite antenna In a tube radio,I going to have to ,because the radio I bought off of eBay ,the ferrite antenna was shattered,so I bought a blank ferrite bar magnetic wire same size,and have heat proof tape,I been trying for days to find anything on a,how to ,I think I can copy it.but I want to do it right .if you have any advice.anyone.

[@12voltvids]

Incandescent bulbs plentiful here. Both conventional and the old Edison type. I have some ferrite bar antennas in a box here. No you can't use LEDs. need that resisitve load.

[@nor4277]

@@12voltvids Have you ever made a replacement ferrite antenna,I bought the ferrite rod and the megnetic wire another tech told me to wrap 60 times,I got some heat proof tape to hold the megnetic wire on,I did try a loop antenna for a.m. stereo amp.that come with a little cheap a.m. antenna didnt work well ,so in a day or two,I going to make my own replacement antenna for my G.E. radio

[@williamsquires3070]

Sadly, incandescent bulbs are now illegal in the U.S. except for specialist applications, such as aquarium/terrarium lighting, and replacements for older Christmas light sets, and vanity lighting. Even there, LEDs are quickly replacing them, and they don’t have the same electrical qualities an incandescent bulb does. I suppose you could find a radio tube with a 117 volt filament?!? Har de har har! :)

[@12voltvids]

The dollar store still sells all types of incandescent lamps here up to 100 watts.

[@m.k.8158]

William Squires they are NOT illegal to SELL, it's the manufacturing, and importation that is. As this was known well in advance, many bulbs were bought before the ban took effect. So there are large inventories all over the country. There is no shortage at this time. Not only that, but even when the pre-ban inventory runs low, l'm fairly sure that some will be imported "under the table". It's tough to check EVERY cargo container.

[@jimreardon6599]

Lots still available, and then there are those "vintage" 60 watt edison bulbs. I see these everywhere these days. Expensive but they look cool and they are incandescent. Loophole in the law that allows these ones. Also garage door, and ceiling fan bulbs are still available, and rough service "surge proof" bulbs. Readily available

[@stphinkle]

Rough service bulbs are still available

[@stphinkle]

Will the heat of the bulb damage the speaker cone?

[@gip-gipsr.1524]

What about slow blow + dim bulb?

[@glenngoodale1709]

Totally awesome video 😂😂😂

[@mikewater1958]

Mounting a light socket without an electrical box? Do you think that's a good idea? You have pinched wires against wood from the wall plug. Looks like a fire hazard to me.

[@12voltvids]

Even if the wires shorted together all that would do is bypass the light. Obviously you have never seen some light fixture installations. I have seen many where there is just a hole in the wall with a wire sticking out and into the fixture and this was a new build done by electrician. Also this radio is not used. It has been used for perhaps 1 or 2 hours total. The entire radio is a bigger fire Hazzard. That's why the light bulb. To prevent excessive current to old electronics.

[@mikewater1958]

@@12voltvids All wire connections should be within an electrical box.

[@12voltvids]

@@mikewater1958 well they are not. 3 bathroom light bars, no box wire run right into fixture and connected inside the light bar, and this was inspected by an electrical inspector for the city and passed. I questioned this and was told that it was to code. The light bar was grounded and as it was a metal box was fine. Electrician said he didn't put boxes in bathroom fixtures because moisture would collect in it. Inspector passed that and failed because a small 7 feet over a bath tub wasn't tempered glass. Go figure.

[@bones007able]

Even if you do a total restoration of a radio, people say don't leave it plugged in because it could start a fire?....well how much more dangerous are these compared to when they were new?.... I doubt the owners manual told customers to unplug it after every use ? I have about a dozen of these and they are all plugged in 24/7 have been for years... but I put a fuse in all of my restorations...I don't see these being anymore likely to start a fire as any other electronic equipment... I had a piece of electronic equipment start a fire ... lucky I was home at the time.... and you know what it was? a modern wall wort for my wireless modem....apparently it shorted and started pouring smoke it was so hot I could not grab it to unplug it.... I can see being careful but anything can cause a fire... even new stuff...

[@12voltvids]

Well older electronics were not built to the same standards as new stuff. Many a fire was caused by short circuits in old radios going way back. So I won't be leaving it plugged in when not in use, which won't be that often as I want it to last as long as possible.

[@GeorgeChristofi]

Also, there were quite a few sets that had the resistive line in the cord to lower the b+. I know them as curtain burners, I'm not sure if you have the same terminology for them over there. The BBC used to end the days TV transmissions with the national anthem and then a warning to unplug your tv set before going to bed. That was easily the case in the seventies if I remember right. We only recently (last 30 years) got 24 hour broadcasting.

[@ikonix360]

@@12voltvids If the radio is properly restored it certainly can be left plugged in and used as much as you ant without fear of the radio not lasting. I restored an RCA K-80 console back in the early 2,000s and use it quite regular. Have yet to have anything fail.

[@12voltvids]

@@ikonix360 you are still dealing with acient transformers. Do you really want to risk it?

[@ikonix360]

@@12voltvids Some radios such as Zenith consoles with the 6X5 rectifier had marginal power transformers, but most had quality transformers and are ok to be used on a regular basis. If I feel a transformer is suspect enough to where I feel that I cannot use the radio as long as I want, I find a new manufacture transformer that has the same specs and replace it.

[@kennethiman2691]

Nice!

[@hanohano034]

Nice

[@ikonix360]

The bulb is dropping voltage and if it drops too much voltage the radio's voltages will be out of spec low and performance will suffer.

[@dirkbonesteel]

#1 I like spiders

[@12voltvids]

Oh you saw that.

[@dirkbonesteel]

Oh yeah, he'll probably enjoy the lightbulb

[@1959Berre]

Do not underestimate your viewers.

[@12voltvids]

Build a nice web around it. That spider will be history soon. Brought the radio inside. Once the cat spots it, it will become a tasty treat.

[@dirkbonesteel]

SAVE THE SPIDER !!!! They are our friends

[@greggchapman2677]

Why can't you add a fuse??

[@12voltvids]

What will a fuse do? If a cap goes leaky it will result in just a rise in current in the milliamp range. Bit enough to blow a fuse till the power transformer shorts.

[@greggchapman2677]

Depends on the fuse value doesn't it? I use a 1/2A slow blow.

[@12voltvids]

@@greggchapman2677 when caps start to go leaky the current increase is gradual and your fuse won't blow untill the transformer shorts. Light bulb prevents that.

[@vetsen]

Spider

[@TheThecyclist]

FIRST!