Sadly, I've seen so very many "curtain burners" relegated to the parts bin to be cannibalized for a very few exchangeable parts. Thanks for putting so much effort into bringing this set back to life!
Wow, 8 years ago, Robyn Williams death! Nonetheless, this was a cool restoration for a really old radio! Nice, I enjoy watching you doing these! Bob from Hudsonville, Michigan
I purchased a Silvertone midget from a junk shop years ago. The owner plugged it it to show me it worked. But I noticed the tubes were so bright, it would have made nice flashlight. Little did I know about resistance line cords, until I cut the ratty old thing off. 3 wires, what is that. Found the schematic inside, and learned about the "curtain burners" as someone else mentioned. There is NO room inside this midget for big resistors. So I used a small metal project box, and cobbled together what power resistors I had laying around. It worked, for about 10 minutes, until the heat from the resistors melted the solder connecting them together. A bunch of sparks came from resistor box. It's just been a display radio ever since. Maybe I get back to that radio someday. Your video helped me understand so much more. Thank You!
With 60Hz mains, the power of the cathodes pulses at 120Hz, and it would pulse at 60Hz with a diode in series. But the diode DOES NOT halve the voltage. It divides it by the square root of 2, so the heaters get about 70% of the RMS voltage. Having 120V mains, the diode feeds the heaters with 85V RMS.
It's unusual to find these tubes dead if the heaters are intact. In the 1930's not a great deal was known about emission characteristics of barium oxide so a greater coating of barium was applied to the cathode than was required for reasonable tube life. This being so the 4,5,6,7 and octal pin tubes lasted almost forever, the miniature tubes or later years however were given a smaller thickness coating of barium on their cathodes and emission life diminished accordingly. The military quality miniature tubes had much longer life due to a greater thickness of barium however. During my Airforce career I had to replace the sub miniature type tubes however due to lack of emission. These were usually wired in but sockets existed in some radios, small as they were. Tube testers were not used, the only sure way was to put a known good tube in it's place. When these were wired into the circuit you made sure the tube was U/S before starting as the procedure as it was time consuming. If all biasing voltages were correct or low and plate & screen voltages were high with dropping resistors correct value you could rest assured that the tube emission was low. Just pure and simple ohms law applied to fault finding.
@@donh01965There was not a way to test a wired in tube in a emission tester so as indicated above the voltage dropping across resistors using ohms law was used to determine emission or lack there of. This is pure and simply diagnostics carried out in your head using mental maths. As a SGT instructor I taught logical fault diagnostics but mostly good fault finding repair techniques is gained by successful repair of individual faults. You must know thermionic electron tube theory well and understand the physics of the fundamentals. Some faults cannot be determined by lack of emission and mutual conductance alone . Some faults are frequency related and in RF circuits these considerations come to the fore.
Thanks for taking us to the memory lane. My dad bought a GE radio in 1947 in Tehran. It had AM, and two SW bands. This was our sole source of entertainment through 50’s and 60’s at home. I built a couple of transistor radios to entertain myself in my room. The radio lasted until 1975! We just kept changing or replenish parts as were needed. Amazing how simple life was.
I know of sets with the so called "Curtain Burner" resistive line cords but I've never actually owned a set that used one. It's just as well that this little Detrola built set has it missing, most have long since cooked themselves to death, the heat bakes the rubber insulation making them hard and brittle. Most of the early series string sets I owned have a ballast tube, or two ballast tubes, and all were imported from the U.S to Canada at some point during their life. Up until 1939 or so the Canadian Electrical Code did not allow for AC/DC or series string sets to be sold, so you have strange things like 4 tube sets with a power transformer.
Hello friend shango good night, it's old friend I love your videos, and today shango I loved to see the concert of this tube radio, I love to see you doing repairs on radios & TVs I really like it asd.. Ricardo salles Franz gunart
1:35:25 - My guess is there IS a back to the cabinet. The idea was to 'isolate' the hot chassis throughout using plastic knobs and no 'exposed' metal. The antenna is exposed but it's electrically isolated.
Years ago I had a Crosley model 515 radio, about the same vintage as that Detrola..the 515 has that same volume control setup..the whole radio circuit is running at full blast, basically. with just the antenna input being regulated..it's kinda cool to listen to it at low level..all the little rumblings and pings and little hums and crackles and stuff that happen normally. :-)
This is almost as good as watching "History Detectives." That's so cool having an 80 year old radio that still works. My oldest working radio is 56 years old.
I love that Nixie tube voltmeter. I have a Nixie digital clock from the 1960's with the 1.5" display. Needs some work, but I'm gonna get that thing working again one day. I love Nixie tube stuff. Good site and great work on old electronics - I'm a child of the 60's and never really learned vacuum tube stuff... Thanks.
lol...watching this 4 years after posting, I forgot who Elliot Rogers was, good thing you snipped a clip in...really is an interesting unit tho--thanks for posting!
Great radio repair, test and fault finding. I loved every minute of your 80 Minute video. Your Military tube tester and Nixie Voltmeter are awesome pieces of test equipment. That resistor had been very hot. That Simpson Voltmeter is a real beauty. Good warm sound too for that old speaker.
1:30:30 I can tell you exactly were I was , what I was doing and what time/day it was when the news broke about Robin Williams death. That gave me chills, especially over that old radio. Just think about how many stories in history that have been delivered by that radio in it's life.
I know how you hate putting modern parts into antique electronics, and I do agree with you, it really defeats the purpose of rebuilding them. That said, I have had great luck putting LED'S in the place of those old tungsten bulbs. I stick the proper size resistor behind it, and build a small holder to put it in the proper location, then choose a color that best matches the age of the set, usually amber or yellow if you will, the bright cold white is just to modern for my taste. If you just want to make it look cool, a bright green is a great bet and adds realism to the feeling of going back in time to play with the past, especially if you hook up an MP3 player, or in my case a wifi radio so you can tune to the old stations that are available on the web. Nothing cooler then to darken the room to what it was when I was a kid living on a farm with no power, a small candle or kerosene lamp in the corner so dad could read his detective magazine while the old battery pack radio played "Suspense," we children gathered around the radio set that was dark so as not to waste energy in the expensive big old brick of a battery pack and jump at every gun shot, shiver when the organ music played the frightening background music as the hero went after the bad guy through the dark alleys of New York City, and place that lived in the back of our minds, we who have never been to a city, in fact a trip to the little town of 2000 souls was considered going to the Big City, the small town was closer it had a population of under 100 with a bar, small grocery store and post office, oh and a small library that had all the wonderful tales for we young folks to read and experience. Indeed those old sets can really take a fellow back, especially if you are an old fart like me, hitting the official old fart age of 69 next week.
Something magical about valve radio's. For years before I acquired proper test equipment in the late 70's and 80's when I started in radio one of the most useful things was a 2 transistor BC109 multivibrator oscillator. Plugged in at the aerial socket and heard through the speaker, everything in the signal path through could be traced and tuned up. A simple yet effective bit of test equipment. I have also used xtal oscillators as signal sources but last year got a synthesised v.f.o. as a signal source. This particular i.f. seems to peak around 468 kHz instead of 455 and the slugs are stuck absolutely solid. This one had the wrong value capacitor inside and the receiver very deaf so I changed it. It's far better now. I'm thinking the cores are sealed into position because all the adjusting plastic pieces break off, I guess so they would never move as this equipment was used in military vehicles, especially tanks, and you can't have things going off tune and losing communication. Bill, G4GHB.
P.S., I remember the tube portable TV's. I used to look down the vent slots to see the glowing tubes. I recall the feeling I got from the warmth coming up. I know, I'm weird. It was a good feeling. It was my parents time when this radio came out.
Very good work again ! I like your videos very much. One issue: In a half way rectifier you dont have a rms voltage of 50% but 70,7%, thats why the heaters are so bright. That was a mistake, I made too, if you erase one of the halfwave of a sinus you may think that it will halfing the voltage, but no way ! Becaus of P = U² / R you have to think in rms. The other problem is the measuring, you cannot measure the unfiltered half-way-voltage with a Voltmeter that measures average and shows "rms" for full-wave-sinus. You have to use a "true-rms"-Voltmeter, but perhaps the FLUKE is one...
At the moment of watching your video, I am working on 1936 Detrola and found your video very informative and useful. One thing I would pass along is that if the "jelly" in the electrolytic caps has leaked it will conduct and can cause arcing. I found out the hard way but didn't blow the transformer.
Great Video. Those resistive mains cords were often fitted to some German made Fluorescent Car Inspection Lamps,the sheath was a silicone type substance, and you could feel the warmth after a few minutes.
I've heard that some vintage test equipment will test components under loads that simulate operating conditions, and that sometimes if a resistor/capacitor tests okay with today's equipment, they may not necessarily be operating correctly under the voltages they were designed to work with.
I remember my Gran had an old Valve radio back in the 60's her antenna stretched all the way down her Garden almost 200 feet, and she had a lightening switch on it for when storms came to ground out the antenna.
Cool video, really enjoyed following along! If the owner intends to use the set on any regular basis then I'd recommend a capacitive dropper arrangement to replace the curtain burner cord. With that there is no heat problem - but you need space for the motor run cap - usually in the large electrolytic can!. The caps are not cheap so it would only be worthwhile if the set was going to be in regular use. First time I watched a clip this long on TH-cam! Cheers, John
We had one of those tube testers as well as the nice tube VOM as necessary tools when I served with The Old Guard at Fort Myer Va. The tube checker got a real workout because most of the Officers and senior NCO'S of the unit figured if we were in communications, we must know how to fix their TV sets, so from day to day, a TV set was found setting on our workbench with a note: From Major So and So, no Horizontal Hold bad sound.. Will pick up Tuesday at 8:00 AM.
It's a shame the owner wont let you shot gun all those old caps. I glad you said to unplug radio when not in use ,I bought a couple of restored radios saying the same thing on a paper that came with my radio,its nice to hear that come firned.
Very nice video! Did anyone else notice the call-letters of all the clear-channel stations on the dial-face? You could clearly see them the light-bulb was replaced. I thought that was pretty neat.
Kind of cool listening to the DJ. I was stationed near a Korean unit in Vietnam, some of their troops would come to our base to trade for American Smokes, guess they couldn't get into our PX to purchase them, so they would bring Korean booze to trade for American Smokes. Hearing them speak with each other was interesting, since I smoked KOOLS, they liked trading with me as menthol seemed to be a favorite among their troops. I got a real taste for their wines, and made some great friends among the boys. One thing about the ROK troops, they were the most brutal troops when it came to prisoner treatment when they captured VC or NVA. Their prisoner life expectancy was near zero after questioning was done. Their officers were nearly as bad to their troops, I attended a 3 week course over Christmas of 1970 with some of them, they were not nearly as good as we were at the course, perhaps because of language problems, when I asked the instructor if they would pass the course, he said that he would pass all of them because in an earlier class he had failed one of their troops, the failure was cause for his superiors to execute him for dishonoring their Army by such poor performance. Now that's pressure to study hard!
Greetings: A 16uf 250vac non-polarized capacitor instead of a resistor will avoid wasting any power, $11.43 shipping included from China. After installing use Kill-a-Watt to check power factor change. They are strict on power factor in Europe, not here. I think green is good. Best of luck. Xc= 1/ (2 pi f c)=165 ohms, C= 16uf. Ceiling fans use these.
The easy ways to tell if they are mica or paper, micas on the schematic will be labeled in uuf example 5000 not .005 also if they are square they are usually mica if they are rectangular and used in circuits other then RF areas they probably paper, there are exceptions, if in doubt check for leakage, micas are very reliable but I have on rare occasions seen them get leaky
What a great story. I learned much(curtain burners, +) and enjoy ,at least trying, to understand the engineering brilliance that brought economy of design to life. Far out seeing GE, RCA and Westing House on one radio. Thanx.......
The #43 tube may be overconducting due to a bad bias resistor, or gas as you mentioned, or it could also be a leaky tone compensation capacitor across the primary of the output transformer. If the #43 is gassy that would explain why it would test good when it obviously is not good, fortunately #43 tubes are not too difficult to find. I must say that Cornell Dubilier made decent paper capacitors if that set was built in 1935 and was still functional, most of the caps that are that old are so leaky that the set will no longer play at all.
A resistance Line Cord. Those were pretty common...surprised you didn' know about those. Good luck finding NOS...even the NOS are brittle. Almost impossible to replace, and probably dangerous to do so.
I spotted a Silvertone midget in a consignment/junk store many years ago. The owner said it "works" and proceeded to plug it in, and turn it on. It played, but the tubes were so bright, it lit up the wall behind it! $10 sure, I'll take it. When I got it home, I found that someone had shortened the frayed power cord. The tuning knob was slightly warped, from the overheated tubes. But still a beauty, waiting to be restored, in my collection. No room inside it for a resistor. Not sure how I'm going to reduce the voltage yet...
Whatever you do, don't bother using a small metal project box and cobbling together whatever power resistors you have laying around. It would likely work, but only for about 10 minutes until the heat from the resistors melt the solder connecting them together. Lots of sparks will follow! At that point in time, it's better to just leave it as a display radio.
You could try a couple of things. One is the diode trick, although that might reduce it too much. Another is to swap the tubes for others where the heater voltages add up to 120 volts.
I honestly think that back in the day it was more common for people to unplug things that weren’t turned on anyways…. A lot of these radios for instance were considered portable so after you’re done listening to it not only is it a good idea to unplug it that’s probably what most people did back in the day too
You seriously think I didn’t know about switch over back in 2009 😂 .... I was putting things in prospective comparing the radio which hasn’t changed since its invention and television
I feel your pain. Ever since the tv changeover, no matter what i use for an antenna, i can barely get reception. And im 35 miles from the city transmitters. I get pixillation, picture freeze. At least with old analog, i got great tv reception with bunny ears. Even if the picture was weak, it was still watchable. It didnt pixillate, it didnt freeze, it still had sound. Analog was far superior to digital tv.
@@tonyp7779 did you try placing your antenna in a window that faces your local transmitter sites (which is not always the same as their city of license)?. If you are trying to use in indoor antenna deep within a building, or the wrong side of the building, multipath will likely doom you for now. Fortunately, the new ATSC 3.0 system will perform much better than ATSC 1.0
I think some companies use resistive power cords if they switch over to modern diodes because their voltage drop is 0.5-0.7v compared to the older selenium rectifiers that have 2-3v per section of the diode assembly.
Had one of those resistance cords on a phonograph. The resistance wound around the rubber covered hot and neutral then cloth covered. You would not know it was there without looking carefully.
really good video. lots of learning goin on. worth the length. only wish you'd tried the hf at night. i really like the old ham radios. thanks again. K6TXE
Boy new filter caps and the hum is gone! Nice! Speaker voice coil needs to be reshimed. You really should test those hot chassis sets with an isolation transformer. I thought that you NEVER wanted to change MICA caps, at least not those made in the USA. I've heard that some foreign made mica's were crap, but NEVER the Aerovox and Micamold jobs.
I was wondering if, instead of the filament string resistors, you could use a diode in series with and filter cap and run DC on the filaments. You might still need like a 20 ohm 10 watt resistor. I guess it might cause too much hum.
Instead of using 2 resistors to lower the voltage, can't you use a diode and a dropping resistor to reduce the voltage and heat? You have to play around with differ value resistors until you achieve the wattage range.
you could...but thats 'polluting' a valve/tube set with a 'modern' semiconductor..a better way is a capacitive dropper using a motor run capacitor, with 1 meg discharge resistor across it, then no heat to drop at all.. if you do use a diode plus resistor dropper, there is a way to calculate the correct value..
Delco was in Dayton, OH in its early years (Delco meant Dayton Electric Company). I believe General Motors bought Delco and moved everything Delco to Detroit to make radios for GM automobiles.
Shango could a 15/20 watt lightbulb be used in lieu of that resistor to get the drop? Or instead perhaps a small regulated dc power supply wired in to deliver the reduced voltage?
Hi to you i had a radio my father had Columbus 5 or 6 valve about the forties never seen one since it had a magic eye 2 or 3 shortwave and one broadcast bands would love to see one again.This is here in new Zealand.
I know this is an ancient video, but what a bizarre and unique circuit that uses...and that's coming from someone who is familiar with radios of that vintage. I've never seen a 4 tube superhet that uses an IF amp but no dedicated preamp tube for the output stage--it's always the IF amp that they skip instead. In order to make that work, they must've driven the hell out of the 6F7, because IF-level signal isn't very strong. LOL @ dim bulb tester with CFL
Only thing you'll test on a vacuum tube using a multimeter is if the filament is good. For earlier stuff this is a fair indication if the thing is worth keeping as they last well, miniature (B7/8/9A etc) ones go low emission more frequently but octal and older tend to work as long as the filament lasts. CRTs another matter, filaments mean little again and a proper tester or letting it run is only way to know.
Instead of a resistance wire or a series of resistors, could you not have used a silicon diode to drop the voltage down to about 62 volts? Just curious. I think it would have worked just as well? And, generated a lot less heat?
The cap can on top probably sounds hollow because it's a wet electrolytic cap inside that can, and the electrolyte solution has either leaked out or dried up. One thing that I noticed is how original that Detrola is under the chassis, all the paper caps, resistors, and even the filter caps are untouched. If it were my set I would be tempted to restuff those old Sprague capacitors, and the electrolytics, and make up replica "dogbone" resistors where the originals were too far off. Would it be worth it, no, not for someone else.
" I think it was louder before I re-capped it " I think you had a bit more speaker before you recapped it. I have old 34 Philco four tube radio that uses the antenna based volume control. It's amazing how with no antenna it controls nothing and local station is real loud, but with good antenna that loud station can be quieted down to nothing.
I have just got done with a radio that had a line-cord. Total heater voltage was only 69 volts & our AC voltage is 240V. I used a capacitive dropper, (which does not produce any heat) for the heater chain. Heat under the chassis is not good. When I replaced any electrolytics I always use 105C types.
good idea, hope you fitted a discharge resistor across the cap(s), other wise if someone unplugged it while switched on, then handled the plug pins, they might get a surprise 😉
+Dale Burrell - It is possible to still end up with a charge on a capacitor in an AC circuit if it is turned off, particularly when the current is at a zero crosspoint of the waveform (it's at full charge at that point). Btw, the poster mentioned 240 volts for a line voltage, which is also probably 50 Hz, not 60.
Suggestion for filament voltage: use a small 240v to 120v step down xfmr to “1/2” the voltage .. or try using diode, choke & maybe resistor as needed …
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Sadly, I've seen so very many "curtain burners" relegated to the parts bin to be cannibalized for a very few exchangeable parts. Thanks for putting so much effort into bringing this set back to life!
Wow, 8 years ago, Robyn Williams death!
Nonetheless, this was a cool restoration for a really old radio! Nice, I enjoy watching you doing these! Bob from Hudsonville, Michigan
I purchased a Silvertone midget from a junk shop years ago. The owner plugged it it to show me it worked. But I noticed the tubes were so bright, it would have made nice flashlight. Little did I know about resistance line cords, until I cut the ratty old thing off.
3 wires, what is that. Found the schematic inside, and learned about the "curtain burners" as someone else mentioned. There is NO room inside this midget for big resistors. So I used a small metal project box, and cobbled together what power resistors I had laying around. It worked, for about 10 minutes, until the heat from the resistors melted the solder connecting them together. A bunch of sparks came from resistor box. It's just been a display radio ever since. Maybe I get back to that radio someday. Your video helped me understand so much more. Thank You!
I'd say use a capacitive dropper, but the capacitors probably need to be massive (in physical size).
I read somewhere, I need to use an A/C motor run capacitor for this to work. @@qwertykeyboard5901
I am in awe of your greatness. This kind of expertise is a dying breed. I sure wish I knew how to do this.
Never too late to get started. Just a warning...electronics is very addictive.
You start off small and grow from there. Then you read the basics about ohms law and you keep 📚 reading 📚
With 60Hz mains, the power of the cathodes pulses at 120Hz, and it would pulse at 60Hz with a diode in series. But the diode DOES NOT halve the voltage. It divides it by the square root of 2, so the heaters get about 70% of the RMS voltage. Having 120V mains, the diode feeds the heaters with 85V RMS.
Correct. Sq rt of 2 is 1.4142. RMS is 70.7% of peak.
As I remember, my radio needs 70 volts, so perhaps a diode would work?@@GeorgeZ213
It's unusual to find these tubes dead if the heaters are intact. In the 1930's not a great deal was known about emission characteristics of barium oxide so a greater coating of barium was applied to the cathode than was required for reasonable tube life.
This being so the 4,5,6,7 and octal pin tubes lasted almost forever, the miniature tubes or later years however were given a smaller thickness coating of barium on their cathodes and emission life diminished accordingly. The military quality miniature tubes had much longer life due to a greater thickness of barium however. During my Airforce career I had to replace the sub miniature type tubes however due to lack of emission. These were usually wired in but sockets existed in some radios, small as they were. Tube testers were not used, the only sure way was to put a known good tube in it's place. When these were wired into the circuit you made sure the tube was U/S before starting as the procedure as it was time consuming.
If all biasing voltages were correct or low and plate & screen voltages were high with dropping resistors correct value you could rest assured that the tube emission was low. Just pure and simple ohms law applied to fault finding.
That's how I do it too, since I have no tube tester, lol.
That's military training, replacements were plentiful, and no time wasted with diagnostics
@@donh01965There was not a way to test a wired in tube in a emission tester so as indicated above the voltage dropping across resistors using ohms law was used to determine emission or lack there of. This is pure and simply diagnostics carried out in your head using mental maths. As a SGT instructor I taught logical fault diagnostics but mostly good fault finding repair techniques is gained by successful repair of individual faults. You must know thermionic electron tube theory well and understand the physics of the fundamentals. Some faults cannot be determined by lack of emission and mutual conductance alone . Some faults are frequency related and in RF circuits these considerations come to the fore.
Thanks for taking us to the memory lane. My dad bought a GE radio in 1947 in Tehran. It had AM, and two SW bands. This was our sole source of entertainment through 50’s and 60’s at home. I built a couple of transistor radios to entertain myself in my room. The radio lasted until 1975! We just kept changing or replenish parts as were needed. Amazing how simple life was.
One of the old "curtain burner" radios.
lol
Dimbulb and Variac - sounds like a pair of comic strip characters you might have seen in Popular Electronics tutorial series back in the day.
I know of sets with the so called "Curtain Burner" resistive line cords but I've never actually owned a set that used one. It's just as well that this little Detrola built set has it missing, most have long since cooked themselves to death, the heat bakes the rubber insulation making them hard and brittle. Most of the early series string sets I owned have a ballast tube, or two ballast tubes, and all were imported from the U.S to Canada at some point during their life. Up until 1939 or so the Canadian Electrical Code did not allow for AC/DC or series string sets to be sold, so you have strange things like 4 tube sets with a power transformer.
That explains the 30's Marconi I had.
That tube tester is so beautiful!!What a the symbol of American quality it is!!
I'm jealous, I want one as well!
Hello friend shango good night, it's old friend I love your videos, and today shango I loved to see the concert of this tube radio, I love to see you doing repairs on radios & TVs I really like it
asd.. Ricardo salles Franz gunart
1:35:25 - My guess is there IS a back to the cabinet. The idea was to 'isolate' the hot chassis throughout using plastic knobs and no 'exposed' metal. The antenna is exposed but it's electrically isolated.
Years ago I had a Crosley model 515 radio, about the same vintage as that Detrola..the 515 has that same volume control setup..the whole radio circuit is running at full blast, basically. with just the antenna input being regulated..it's kinda cool to listen to it at low level..all the little rumblings and pings and little hums and crackles and stuff that happen normally. :-)
By far one if the best electronics diagnosis channels on YT imho.
Thats so cool, it even picks up stations from way back then and from foreign countries too.
This is almost as good as watching "History Detectives." That's so cool having an 80 year old radio that still works. My oldest working radio is 56 years old.
Sir it very old radio of 1935 . Amazing and unbelievable .
I love that Nixie tube voltmeter. I have a Nixie digital clock from the 1960's with the 1.5" display. Needs some work, but I'm gonna get that thing working again one day. I love Nixie tube stuff. Good site and great work on old electronics - I'm a child of the 60's and never really learned vacuum tube stuff... Thanks.
Wet Tex Ive been looking for a nixie clock from the 60’s or 70’s. Who made yours?
lol...watching this 4 years after posting, I forgot who Elliot Rogers was, good thing you snipped a clip in...really is an interesting unit tho--thanks for posting!
Great radio repair, test and fault finding. I loved every minute of your 80 Minute video. Your Military tube tester and Nixie Voltmeter are awesome pieces of test equipment.
That resistor had been very hot. That Simpson Voltmeter is a real beauty. Good warm sound too for that old speaker.
1:30:30 I can tell you exactly were I was , what I was doing and what time/day it was when the news broke about Robin Williams death. That gave me chills, especially over that old radio. Just think about how many stories in history that have been delivered by that radio in it's life.
I know how you hate putting modern parts into antique electronics, and I do agree with you, it really defeats the purpose of rebuilding them. That said, I have had great luck putting LED'S in the place of those old tungsten bulbs. I stick the proper size resistor behind it, and build a small holder to put it in the proper location, then choose a color that best matches the age of the set, usually amber or yellow if you will, the bright cold white is just to modern for my taste. If you just want to make it look cool, a bright green is a great bet and adds realism to the feeling of going back in time to play with the past, especially if you hook up an MP3 player, or in my case a wifi radio so you can tune to the old stations that are available on the web. Nothing cooler then to darken the room to what it was when I was a kid living on a farm with no power, a small candle or kerosene lamp in the corner so dad could read his detective magazine while the old battery pack radio played "Suspense," we children gathered around the radio set that was dark so as not to waste energy in the expensive big old brick of a battery pack and jump at every gun shot, shiver when the organ music played the frightening background music as the hero went after the bad guy through the dark alleys of New York City, and place that lived in the back of our minds, we who have never been to a city, in fact a trip to the little town of 2000 souls was considered going to the Big City, the small town was closer it had a population of under 100 with a bar, small grocery store and post office, oh and a small library that had all the wonderful tales for we young folks to read and experience. Indeed those old sets can really take a fellow back, especially if you are an old fart like me, hitting the official old fart age of 69 next week.
Something magical about valve radio's.
For years before I acquired proper test equipment in the late 70's and 80's when I started in radio one of the most useful things was a 2 transistor BC109 multivibrator oscillator. Plugged in at the aerial socket and heard through the speaker, everything in the signal path through could be traced and tuned up. A simple yet effective bit of test equipment. I have also used xtal oscillators as signal sources but last year got a synthesised v.f.o. as a signal source.
This particular i.f. seems to peak around 468 kHz instead of 455 and the slugs are stuck absolutely solid. This one had the wrong value capacitor inside and the receiver very deaf so I changed it. It's far better now. I'm thinking the cores are sealed into position because all the adjusting plastic pieces break off, I guess so they would never move as this equipment was used in military vehicles, especially tanks, and you can't have things going off tune and losing communication.
Bill, G4GHB.
Love the Fairchild meter so much I found one for myself. And still dead on. These could not have been cheap when new.
Hi Shango. I know a man who's going to be pleased,with your repairs. Great job has always.
Bobby
P.S., I remember the tube portable TV's. I used to look down the vent slots to see the glowing tubes. I recall the feeling I got from the warmth coming up. I know, I'm weird. It was a good feeling.
It was my parents time when this radio came out.
For reading those old carbon rod resistors, I use a "crutch". BED -- Body; End; Dot. Thanks for the video!
Dave
@ 42:47..."pretty much works right out of the box" That cracked me up big time!
Very interesting and informative journey...Thank You!
Very good work again ! I like your videos very much.
One issue:
In a half way rectifier you dont have a rms voltage of 50% but 70,7%, thats why the heaters are so bright. That was a mistake, I made too, if you erase one of the halfwave of a sinus you may think that it will halfing the voltage, but no way ! Becaus of P = U² / R you have to think in rms. The other problem is the measuring, you cannot measure the unfiltered half-way-voltage with a Voltmeter that measures average and shows "rms" for full-wave-sinus. You have to use a "true-rms"-Voltmeter, but perhaps the FLUKE is one...
At the moment of watching your video, I am working on 1936 Detrola and found your video very informative and useful. One thing I would pass along is that if the "jelly" in the electrolytic caps has leaked it will conduct and can cause arcing. I found out the hard way but didn't blow the transformer.
Great Video. Those resistive mains cords were often fitted to some German made Fluorescent Car Inspection Lamps,the sheath was a silicone type substance, and you could feel the warmth after a few minutes.
I've heard that some vintage test equipment will test components under loads that simulate operating conditions, and that sometimes if a resistor/capacitor tests okay with today's equipment, they may not necessarily be operating correctly under the voltages they were designed to work with.
I remember my Gran had an old Valve radio back in the 60's her antenna stretched all the way down her Garden almost 200 feet, and she had a lightening switch on it for when storms came to ground out the antenna.
Cool video, really enjoyed following along! If the owner intends to use the set on any regular basis then I'd recommend a capacitive dropper arrangement to replace the curtain burner cord. With that there is no heat problem - but you need space for the motor run cap - usually in the large electrolytic can!. The caps are not cheap so it would only be worthwhile if the set was going to be in regular use. First time I watched a clip this long on TH-cam!
Cheers, John
A run cap may work but I still town like the idea of using capacitors. I know it ran on forever. I bet the average retention will be like 4 minutes
Those old monster Tubes or Valves as we call them in the UK remind me of my Grandads old 1930s British Set.
We had one of those tube testers as well as the nice tube VOM as necessary tools when I served with The Old Guard at Fort Myer Va. The tube checker got a real workout because most of the Officers and senior NCO'S of the unit figured if we were in communications, we must know how to fix their TV sets, so from day to day, a TV set was found setting on our workbench with a note: From Major So and So, no Horizontal Hold bad sound.. Will pick up Tuesday at 8:00 AM.
Reminds me of High School auto shop class, the Vice Principal would get his tires rotated and oil changed on the regular for free.
I remember an old timer mentor said... those resistive line cords used to light the drapes. A resistor in the power cord? Wow.
It's a shame the owner wont let you shot gun all those old caps. I glad you said to unplug radio when not in use ,I bought a couple of restored radios saying the same thing on a paper that came with my radio,its nice to hear that come firned.
Yep!..that tube tester.. I had one of those years ago... awesome.. i love vintage military electronics. :-)
Some great music there especially yesterday when I was young
I just wanted to comment and thank you for the time you take. upload, and teach us - Thank you. Love the videos!
Very nice video!
Did anyone else notice the call-letters of all the clear-channel stations on the dial-face? You could clearly see them the light-bulb was replaced. I thought that was pretty neat.
Great video. Really enjoyed it. Thanks Shango.
Carl
Kind of cool listening to the DJ. I was stationed near a Korean unit in Vietnam, some of their troops would come to our base to trade for American Smokes, guess they couldn't get into our PX to purchase them, so they would bring Korean booze to trade for American Smokes. Hearing them speak with each other was interesting, since I smoked KOOLS, they liked trading with me as menthol seemed to be a favorite among their troops. I got a real taste for their wines, and made some great friends among the boys. One thing about the ROK troops, they were the most brutal troops when it came to prisoner treatment when they captured VC or NVA. Their prisoner life expectancy was near zero after questioning was done. Their officers were nearly as bad to their troops, I attended a 3 week course over Christmas of 1970 with some of them, they were not nearly as good as we were at the course, perhaps because of language problems, when I asked the instructor if they would pass the course, he said that he would pass all of them because in an earlier class he had failed one of their troops, the failure was cause for his superiors to execute him for dishonoring their Army by such poor performance. Now that's pressure to study hard!
in my side of the world - uk we use capacitive droppers to replace resistive cord or replacing hot running dropper resistors in ac/dc sets
Greetings:
A 16uf 250vac non-polarized capacitor instead of a resistor will avoid wasting any power, $11.43 shipping included from China. After installing use Kill-a-Watt to check power factor change. They are strict on power factor in Europe, not here. I think green is good. Best of luck. Xc= 1/ (2 pi f c)=165 ohms, C= 16uf. Ceiling fans use these.
Amazing engineering and imagination by the way back in the day “slide rule” engineers …
Good work as always Shango066! I learned A LOT by watching your Videos.
Great video, Shango. I feel like I'm getting a college course for free from you. Thanks brother.
1:12:46 - Mica capacitors are very stable - don't need to be replaced.
The easy ways to tell if they are mica or paper, micas on the schematic will be labeled in uuf example 5000 not .005 also if they are square they are usually mica if they are rectangular and used in circuits other then RF areas they probably paper, there are exceptions, if in doubt check for leakage, micas are very reliable but I have on rare occasions seen them get leaky
What a great story. I learned much(curtain burners, +) and enjoy ,at least trying, to understand the engineering brilliance that brought economy of design to life. Far out seeing GE, RCA and Westing House on one radio. Thanx.......
The #43 tube may be overconducting due to a bad bias resistor, or gas as you mentioned, or it could also be a leaky tone compensation capacitor across the primary of the output transformer.
If the #43 is gassy that would explain why it would test good when it obviously is not good, fortunately #43 tubes are not too difficult to find. I must say that Cornell Dubilier made decent paper capacitors if that set was built in 1935 and was still functional, most of the caps that are that old are so leaky that the set will no longer play at all.
The Capacitive dropper comes to mind in this situation? Nice way to drop some AC with no heat or resistors.
lol at 30 minutes in. Did you pick up Dalek Radio?
Thanks for another great jurassetronics video.
This is a great video. I had seen it before and I guess I forgot to comment.
Excellent video, really enjoyed watching this one. I coveted that Nixie MM of yours.
Andrew
For the filament ballast you could use a 20mfd AC capacitor like used on motors. Larger than resistor, but no heat.
+JAMES AZBELL - The figure I come up with is 7.8 mf to get the appropriate voltage drop.
A resistance Line Cord. Those were pretty common...surprised you didn' know about those. Good luck finding NOS...even the NOS are brittle. Almost impossible to replace, and probably dangerous to do so.
even more dangerous here in the on our 240v ish mains.... and with the switch in the chassis side.. 😲
I spotted a Silvertone midget in a consignment/junk store many years ago. The owner said it "works" and proceeded to plug it in, and turn it on. It played, but the tubes were so bright, it lit up the wall behind it! $10 sure, I'll take it. When I got it home, I found that someone had shortened the frayed power cord. The tuning knob was slightly warped, from the overheated tubes. But still a beauty, waiting to be restored, in my collection. No room inside it for a resistor. Not sure how I'm going to reduce the voltage yet...
metalmoto The bright tubes could be heater to cathode shorts. Good luck!
Whatever you do, don't bother using a small metal project box and cobbling together whatever power resistors you have laying around. It would likely work, but only for about 10 minutes until the heat from the resistors melt the solder connecting them together. Lots of sparks will follow! At that point in time, it's better to just leave it as a display radio.
You could try a couple of things. One is the diode trick, although that might reduce it too much. Another is to swap the tubes for others where the heater voltages add up to 120 volts.
I honestly think that back in the day it was more common for people to unplug things that weren’t turned on anyways…. A lot of these radios for instance were considered portable so after you’re done listening to it not only is it a good idea to unplug it that’s probably what most people did back in the day too
It's unbelievable that you can still receive broadcasts on a 84 year old radio but you can't receive anything on a not even 20 year old TV
Go to a thrift store and by a DTV converter box. Not only will you be able to watch your TV, you'll also be adding remote control to it.
You seriously think I didn’t know about switch over back in 2009 😂 .... I was putting things in prospective comparing the radio which hasn’t changed since its invention and television
I feel your pain. Ever since the tv changeover, no matter what i use for an antenna, i can barely get reception. And im 35 miles from the city transmitters. I get pixillation, picture freeze. At least with old analog, i got great tv reception with bunny ears. Even if the picture was weak, it was still watchable. It didnt pixillate, it didnt freeze, it still had sound. Analog was far superior to digital tv.
@@tonyp7779 did you try placing your antenna in a window that faces your local transmitter sites (which is not always the same as their city of license)?.
If you are trying to use in indoor antenna deep within a building, or the wrong side of the building, multipath will likely doom you for now.
Fortunately, the new ATSC 3.0 system will perform much better than ATSC 1.0
I have a 1958 Emerson 24" TV that works - for about 20 minutes, before the horizontal sync dies out.
I'm having a locating the trouble spot😒
I think some companies use resistive power cords if they switch over to modern diodes because their voltage drop is 0.5-0.7v compared to the older selenium rectifiers that have 2-3v per section of the diode assembly.
Had one of those resistance cords on a phonograph. The resistance wound around the rubber covered hot and neutral then cloth covered. You would not know it was there without looking carefully.
The most interesting thing about this set is the call letters arranged on the dial by network.
really good video. lots of learning goin on. worth the length. only wish you'd tried the hf at night. i really like the old ham radios. thanks again. K6TXE
when I was in the army in the seventies the TV7 tube tester was our standard tester.
Where do you get all that badass testing equipment?? I would kill for a multimeter like that!!!
Boy new filter caps and the hum is gone! Nice!
Speaker voice coil needs to be reshimed.
You really should test those hot chassis sets with an isolation transformer.
I thought that you NEVER wanted to change MICA caps, at least not those made in the USA. I've heard that some foreign made mica's were crap, but NEVER the Aerovox and Micamold jobs.
Kenneth Scharf Some mica caps can self-destruct, even those made in the USA. Hence the nickname “micabomb”
LMAO..get a clapper switch..are you appearing all week? Priceless shit!
I was wondering if, instead of the filament string resistors, you could use a diode in series with and filter cap and run DC on the filaments. You might still need like a 20 ohm 10 watt resistor. I guess it might cause too much hum.
Instead of using 2 resistors to lower the voltage, can't you use a diode and a dropping resistor to reduce the voltage and heat? You have to play around with differ value resistors until you achieve the wattage range.
you could...but thats 'polluting' a valve/tube set with a 'modern' semiconductor..a better way is a capacitive dropper using a motor run capacitor, with 1 meg discharge resistor across it, then no heat to drop at all.. if you do use a diode plus resistor dropper, there is a way to calculate the correct value..
I heard Rush in the background - I sure miss him.
He was entertaining. I listened to him during Clinton years. Limbaugh was the master
@@donh01965I can't help to wonder what he would say today, of course regarding Biden. I listened to his show since 1988.
keep it up love your stuff I have learned a lot
Delco was in Dayton, OH in its early years (Delco meant Dayton Electric Company).
I believe General Motors bought Delco and moved everything Delco to Detroit to make radios for GM automobiles.
Shango could a 15/20 watt lightbulb be used in lieu of that resistor to get the drop? Or instead perhaps a small regulated dc power supply wired in to deliver the reduced voltage?
Hi to you i had a radio my father had Columbus 5 or 6 valve about the forties never seen one since it had a magic eye 2 or 3 shortwave and one broadcast bands would love to see one again.This is here in new Zealand.
На 34 минуте примерно запах нагретой пыли с ламп пошел еле отмахался :)
Shango, 9k views. Looks like this radio was a zinger... Good for you. Steven
No, 17K views!!
No, 79,841 views.
I was introduced to warm dropping cords from old equipment my father owned. I can’t see the cord setting a curtain on fire, but maybe.
I worked at Sams when they had Nixie tube meters on the tech benches.
I know this is an ancient video, but what a bizarre and unique circuit that uses...and that's coming from someone who is familiar with radios of that vintage. I've never seen a 4 tube superhet that uses an IF amp but no dedicated preamp tube for the output stage--it's always the IF amp that they skip instead. In order to make that work, they must've driven the hell out of the 6F7, because IF-level signal isn't very strong. LOL @ dim bulb tester with CFL
How can I test tubes or even a CRT tube with at home stuff like a multimeter
Only thing you'll test on a vacuum tube using a multimeter is if the filament is good. For earlier stuff this is a fair indication if the thing is worth keeping as they last well, miniature (B7/8/9A etc) ones go low emission more frequently but octal and older tend to work as long as the filament lasts. CRTs another matter, filaments mean little again and a proper tester or letting it run is only way to know.
Instead of a resistance wire or a series of resistors, could you not have used a silicon diode to drop the voltage down to about 62 volts? Just curious. I think it would have worked just as well? And, generated a lot less heat?
This was one of the precursors to the postwar-era AA5 radio.
The cap can on top probably sounds hollow because it's a wet electrolytic cap inside that can, and the electrolyte solution has either leaked out or dried up. One thing that I noticed is how original that Detrola is under the chassis, all the paper caps, resistors, and even the filter caps are untouched. If it were my set I would be tempted to restuff those old Sprague capacitors, and the electrolytics, and make up replica "dogbone" resistors where the originals were too far off. Would it be worth it, no, not for someone else.
I've rejuvenated powdered speaker cones with newspaper and Elmer's white glue. And BTW, re: the resistor temp, remember Farenheit 451.
I've seen coffee filters used with great success
My dad, who was an RCA tech in the 50's, told me the foil end of the cap, unless otherwise specified, always connects to the tube.....
Great job 👍 Shango 0 66
" I think it was louder before I re-capped it "
I think you had a bit more speaker before you recapped it.
I have old 34 Philco four tube radio that uses the antenna based volume control.
It's amazing how with no antenna it controls nothing and local station is real loud, but with good antenna that loud station can be quieted down to nothing.
I have just got done with a radio that had a line-cord. Total heater voltage was only 69 volts & our AC voltage is 240V. I used a capacitive dropper, (which does not produce any heat) for the heater chain. Heat under the chassis is not good.
When I replaced any electrolytics I always use 105C types.
good idea, hope you fitted a discharge resistor across the cap(s), other wise if someone unplugged it while switched on, then handled the plug pins, they might get a surprise 😉
+Dale Burrell - It is possible to still end up with a charge on a capacitor in an AC circuit if it is turned off, particularly when the current is at a zero crosspoint of the waveform (it's at full charge at that point). Btw, the poster mentioned 240 volts for a line voltage, which is also probably 50 Hz, not 60.
Suggestion for filament voltage: use a small 240v to 120v step down xfmr to “1/2” the voltage .. or try using diode, choke & maybe resistor as needed …
How does the Nixi tube meter compare with an analog sweep style meter
I used to think these old radios would pick up broadcasts from the 1930's.
When playing one when I was a kid, I was amazed it 'knew' how to play modern music.
They don't??
Hi..my Philco does the same thing the raspy sound at 38:10 in the video..do you know what causes this...??? thanks..
How do you know what plate voltages, etc should be if they arent on the skematic?
The wisdom of human ancestors
wow that tube tester
attach a heat-sink to the resistors like the ones on mosfets..you think that would work??
I like the drawring of the alligator w/ his tongue hanging out... oh, that's a strange power input haha oh well..
That thing sounds like attack of the daleks when tuned into a station (around 34mins in)
I always repair valve radios he in Brasil. I do like to repairing oldies equipment. It´s my opportunity to know about oldies tecnologies.