Excellent progression dealing with the voltage dropping issue! I restored a 1938 Emerson AX-211 that also used a curtain burner cord. The Bakelite radio case was extremely cramped, with no room for either a power resistor or large cap. So I remade the cord and retained the original asbestos insulated resistance lead, then encased the conductors with fireproof sheathing. The radio works nicely now and the cord gets just a little warm, as long as it remains extended.
Wow a 30+ minute show without commercials. Thanks! Enjoy your videos. And thanks for the references to electronics school. I went from 1978-1980 with around 2400 hours in the classroom. Compared to high school, i had a ball.
Aras Mahmood -the idea makes sense. Capacitors “ conduct” AC as they are used for audio interstage as well as in speaker cabinets to couple speakers of different frequency ranges. The trick for replacing the line cord resistors is determining the capacitor value , but since there are not actually that many different heater string combinations , a “cheat sheet” can be compiled to find the correct capacitor value
Nice oldie!! A treasure! Good job! I tried for an electronics degree, but gave it up. Trig is a requirement. I couldn't even get past complicated algebra . But got A's in the electronics classes . I even made a breadboard digital circuit once. Never had much hands on experience on electronics that I wish I had . I'd like to have you as a teacher, but you'd lose your patience with me, lol. I really enjoy your videos. You are now my favorite channel. P.S. I suppose if that cap you installed decided to short, bye bye tubes.
I've never tried using a capacitor in the heater chain before. I've heard of people doing it, but until now, I've never actually seen it in action---well done, and a great vid.
Awesome job! Using the resources that are available in your shop to get to an acceptable solution that works and to prove that out with direct measurements of line voltages. Every aspiring technician/hobbyist should be watching your channel. Thank you for sharing your knowledge with us.
It's a pleasure watching your videos, no doubt that your super talented. I've been restoring for about 20 yrs and had family in the radio/tv repair field. That started my love of electronics. Thank You for all the effort and great advice. With you and "All American Five" Showing us how to do the Job RIGHT we can't go wrong. Take Care Tony Beatrice
Another excellent video, and nicely done safety upgrades, capacitor upgrade, and restoration! About ten years ago, I purchased a box of old items from an estate auction at a farmhouse in Wagontown, PA. Inside, I found a payment book and catalog from " The National Farmer's Grange League", which sponsored community halls across most of the United States. They sold Aetna, Halson, and Westinghouse radios through that catalog, which also carried Cooper Tires, Rexall animal medications, canoes, Mossberg rifles and shotguns, husbandry supplies, and even Minneapolis-Moline tractors. I saw a notation which stated that Sears- Roebuck provided the warranty service for everything electrical. I remember that the payment for one of the radios listed (in 1936) was 0.35¢ per week, and that "seven cents of each dollar that you spend profits your Community Grange".
For sets with just a few 300mA tubes: with the rectifier diode method you can add a resistor in series with it to get the filament supply voltage down to where it should be for the series string of tubes.
I truly enjoy all of the videos you have done and am amazed at the ease you seem to have solving problems. Perhaps one day you might show us just where you are hooking your probes/leads up to while taking your measurements, not just with the voltages, but also when connecting signal generators or oscilliscopes. I haven't had a great deal of experience with test instruments, but it is obvious that you have and I'd really like to benefit from your experience. Thanks for another great video. Best 73's~N4TYX~Ed Allen
Would there be enough room for a 12.6 volt center tap transformer in there? Put the 12 volt filaments across the entire secondary and the 6 volt filaments across the center tap.
Great commentary. I enjoy watching your video's. Keep up the great work. For the voltage dropping capacitor it is good practise top put a 1 or 1.5 Meg ½ or 1 Watt resistor across its terminals, to discharge the Cap when the radio is turned off.
I wonder if you use some heat sink compound on the back of the power resistor when you mount it on the chasis ,if that would be a little extra help.to.transfer more heat to the radio chasis ?
+Ron Thompson - The problem is that the chassis is small and trying to use it as a heat sink would bring it and the cabinet to undesirable, possibly dangerously high temperatures.
A fuse could be added in series with the capacitor and tube filaments, to protect the scarce vintage tubes if the capacitor fails in a short circuit mode. After warm up, the filament current is rated at 0.3 A. When the tube filaments are cold, their resistance is lower, but the capacitor will limit current. I estimate peak current under 0.4 A and suggest a 0.5 A fuse in series with the filaments and capacitor. Usually, one side of the line cord connected through the switch to the chassis. I suggest a polarized line cord with the switch rewired: neutral conductor tied directly to the chassis and "hot" conductor wired through the switch. Better yet, use a GFI plug and cord scavenged from a second hand store hair dryer. This cord is also polarized and should be wired at the chassis the same way as for non GFI but polarized line cord.
The idea of using a cap to drop heater voltages is an excellent approach to making these old “junker” radios play again safely. Still receives many stations considering it is only a TRF circuit. Using an RF sensitivity control in stead of an AF volume control is really old tech even for the 1930s. Was the builder of the set trying to save a buck by not employing AVC ? That would have required paying a licensing fee for the application of AVC . I am always curious about who actually built these “jobber” sets. I know that Aetna ( Walgreens ) often used Simplex Mfg out of Sandusky , Oh. Simplex even built some sets for Philco including portables and Auto radio’s until Philco bought them out...
Can the capacitor be used on transformer operated radios too? Just to make the transformer a little happier from all the heat it puts off or do i have other problems. I restored an Arvin 417 (Noblitt Sparks) and after a couple hours,the transformer is real hot to the touch. No known shorts in the set in any of the stages. All caps replaced too..
I just bought a 1941 Pilot model B 1 with a line cord that has a resistor built in.It will be here next week;I got it off of ebay.Should it be bad,I'll know how to replacement.Thanks again for the video.Any info is greatly appreciated.
Great Job! I'd be willing to bet that radio was made by a company named Detrola here in Detroit? They made a lot of those "House Brand" radios, for just about everybody. Keep up the good work. Brendan
I was watching your repair video and you indicated there was a electronic parts supplier named Miles of Myles you like to purchase parts from, especially the resistors for resistance cord replacement. Can you repost the website for the supplier?Thanks
Very interesting video! I didn't know Walgreens had a store brand radio back then. In the 90's their house brand radios were Tozai that were made in....guess?
Interesting radio. I see one on ebay with the line cord removed and no mention of the line cord resistor... I hope no one gets it and decides to slap a regular cord on it...
It only works if the frequency is reliable and you know it. The reactance, X (in ohms) is 1/6.28FC, so C is 1/6.28FX. You can use Ohm's law to calculate voltage from current or current from voltage, BUT the voltage is "imaginary", so you either have to use sines and cosines or phasors to add it to other voltages in the circuit. In this case, since the phase angle is -90 across the cap and 0 across everything else, you can fit them into the formula for a right triangle (see my hack above). All these calculations only work as stated for a clean sine wave; the cap will still drop voltage reliably for a square wave or a sawtooth, etc. , but the math would be much more complicated and trial & error would probably be easier than figuring it out.
America First The capacitor only works for A.C. voltage- depending on the frequency of the voltage, and the size of the capacitor, the A.C. current can be controlled.
My mother was born in 1935 so this radio is as old as she is. I've heard my father say many times that it was common when he was a kid that many radios were run on batteries and he was born in 1928.
Good repair, and thanks for the very good clear explanation of the series heater chain and the options you have for repair. Here in the UK you have to drop a lot more volts and the big chassis mount resistor is the norm in AC/DC sets, horrible things that get very hot and are often found to be open when you get the set. Some of the guys here replace them with capacitors but like you, the math is a mystery to me!! Incidentally, why did they bother with a TRF when with 4 tubes they could have had a simple superhet with better sensitivity and selectivity? Just to save the cost of 2 IF transformers I guess.
I read somewhere that in the '50s and '60s they imported some "AA5" radios that were designed around 120 volt mains to the UK from the USA or Japan, with added "curtain burner" cords to drop the remaining 110 or 120 volts. I've always wondered how those fared and what people did with them when the cords failed.
I had a discussion with a fellow on one of the forums about the dropper diodes. I suggested using the 3 amp type rather then the usual 1 amp 1N4007 types, and to use two in series if one were going to go with the diode dropper method. He insisted that it was unnecessary using 3 amp diodes since the filament only draw 300 ma, and that two in series was unnecessary for the same reason. So I asked the rhetorical question, which is cheaper, buying a new set of tubes at between $1 to $10 each, or spending an extra $.20 on better diodes and using an extra diode? Point in fact I don't like the diode dropper method at all, BandersenTV ran some experiments with each dropper type on a series string T.V set. First, you usually need a combination of a diode and a resistor since the diode seldom drops exactly what you need. Second, the diode droppers are instant on, there is no cushion for the tubes to warm up, so you really need a current limiting device in series with the string. He found that the capacitive dropper was probably the best for soft starting the tubes, but as with the diode it's hard to get the voltage exactly right without using a resistor in combination with it. You are right about the peak to peak voltage with the diode I think, which is why you really need to use some formulas to calculate how much drop you are going to get and how much you need to add rather then a using a VOM.
+OlegKostoglatov - I'm coming in a little late on your post but the thing about the diode solution is that they only provide a fixed "average voltage" from the line and as you mentioned, will almost always need an additional component to tailor the voltage to what is needed. As I recall from my electronics math, the average value of the half wave pulsating DC voltage that results is equal to the peak voltage x 1/Pi, which for 120v comes out to 38 volts and change--actually less than what is needed. This actually makes sense since, as you know, the diode method was used extensively in tube sets to provide the instant on feature. I do remember seeing how much fainter the tubes glowed when such sets were "off." So in reality, the diode method would not work for this application. [EDIT]: DOH! Little mistake in my figures. I used the RMS value for the line voltage instead of the peak value. The actual answer comes out to just under 54 volts. Again, still less than what is needed. My bad.
I'm fairly new to the hobby and can't say that I know a whole lot yet, but I'm wondering why a transformer wouldn't be a better choice if one of the right value could be found.
One thing to remember, is that in a SERIES circuit, the individual tube heaters can be all different VOLTAGES, but ALL of tube heaters MUST draw the same CURRENT.
It appeared that you were pointing to an electrolytic capacitor and saying it was across the line. If so, it really shouldn't be an electrolytic but a safety cap...in fact, regardless of what it was, it should be a safety cap.
you would wire the diodes in parallel wouldn't you, so that if one diode failed the other diode would pick up the load like the alternator in a car can do
+I Eat What I Grow - No. They would be in series, so that if one shorts the other would still be in line rectifying the heater current. At least that's the idea.
The diode doesnt work, just like you see it glows too bright. I would like to see the difference in wattage consumption between the cap and the resistor. Should be half
I know. The way to do it is Mylar wiring, and two ceramic resistors in series. Shango I can show you how to use this method, if you wish. Then a long antenna wire, and always unplug the device later, don't depend on the pot. Get a Chinese power strip or something ok? Lol!!!! Steven
8:15 I think I can hack my way around most of the complex math, though maybe the nostalgiaar people beat me to it. With the same .3 A current and 62 "real" volts across the rest of the string, the voltage across the capacitor will be "imaginary" (90 deg out of phase), so they are like 2 legs of a right triangle with a hypotenuse of 120. So 120 squared minus 62 squared is 10,556, the square root of which yields 103 V. 103 V/.3 A is 343 ohms reactance or X. With C = 1/6.28FX, we get 7.73 MFD, which is a little less than the 10 MFD that was a little too big (18:08). That might save someone from having to order more than one cap.
I enjoy your videos. Could you make a guitar amp repair video sometime? Preferably a Marshall or Fender tube amp. There's lots of schematics available.
May I ask were you went to school,for all your electrical know age. You are really good at what you do with old radios,,the rweason I like tube radios is the sound.its better
Capacitors and diodes can short. I would have used the metal cased resistor or a ceramic resistor. I wasn’t any good with the math and formulas either. No problem with ohms law formulas. Ran into problems in R C circuit formulas
In another section of the last of the 4 links you provided, they have all the ways of calculating various voltage dropping schemes and they have an Excel spreadsheet developed by Paul Stenning that you can download free to do the maths for you. Google: "dropper calculations spreadsheet" It includes the resistor, capacitor and diode methods -and a few combinations to boot. TRF's can be very sensitive and selective, but design is everything. I homebrewed a VHF only TRF receiver that is more sensative and selective than any of my modern VHF radios, or any of my 3 SDRs for that matter.
you can use two resistors in parralel, both twice the value of the one you have (half the power over one of the two resistors, is less heat!) but the cap is the best idea!
I have a similar style radio to deal with at the moment. I have already purchased some of the Racol resistor for testing purposes but I may use a diode half power or capacitive dropper. I haven’t decided yet it will depend on the dissipation within the radio cabinet. Unfortunately it more of a problem for me in the U.K. as we have a 230 volt supply. If you fancy a quick look I have included a link but it’s not your normal repair video ua-cam.com/video/GRYLdkwXzpI/v-deo.html. Thanks stay safe my best regards Chris
It never fails to amaze me how well these TRF sets work. Great to see.
Excellent progression dealing with the voltage dropping issue! I restored a 1938 Emerson AX-211 that also used a curtain burner cord. The Bakelite radio case was extremely cramped, with no room for either a power resistor or large cap. So I remade the cord and retained the original asbestos insulated resistance lead, then encased the conductors with fireproof sheathing. The radio works nicely now and the cord gets just a little warm, as long as it remains extended.
How hot did those cables really get were they are uncomfortable to touch?
@@TechHowden Only warm, unless they were tightly coiled.
Wow a 30+ minute show without commercials. Thanks! Enjoy your videos. And thanks for the references to electronics school. I went from 1978-1980 with around 2400 hours in the classroom. Compared to high school, i had a ball.
First time for me to know that you can use capacitor instead of power resistor. Thank you very much for this info.
Aras Mahmood -the idea makes sense. Capacitors “ conduct” AC as they are used for audio interstage as well as in speaker cabinets to couple speakers of different frequency ranges. The trick for replacing the line cord resistors is determining the capacitor value , but since there are not actually that many different heater string combinations , a “cheat sheet” can be compiled to find the correct capacitor value
Nice oldie!! A treasure! Good job!
I tried for an electronics degree, but gave it up. Trig is a requirement. I couldn't even get past complicated algebra .
But got A's in the electronics classes . I even made a breadboard digital circuit once. Never had much hands on experience on electronics that I wish I had . I'd like to have you as a teacher, but you'd lose your patience with me, lol. I really enjoy your videos. You are now my favorite channel. P.S. I suppose if that cap you installed decided to short, bye bye tubes.
I've never tried using a capacitor in the heater chain before. I've heard of people doing it, but until now, I've never actually seen it in action---well done, and a great vid.
Great lesson on early t.r.f!! Thank you for carefully explaining how to resolve that kind of repair! You're pretty darn clever! Have a good christmas.
Awesome job! Using the resources that are available in your shop to get to an acceptable solution that works and to prove that out with direct measurements of line voltages. Every aspiring technician/hobbyist should be watching your channel. Thank you for sharing your knowledge with us.
Very impressive. It's good to see someone restoring these nice old machines.
I use 60 lb fishing line for dial cord replacement. Lasts a lifetime!!!! I also use rubber o rings for vcr idler tires
It's a pleasure watching your videos, no doubt that your super talented. I've been restoring for about 20 yrs and had family in the radio/tv repair field. That started my love of electronics. Thank You for all the effort and great advice. With you and "All American Five" Showing us how to do the Job RIGHT we can't go wrong.
Take Care Tony Beatrice
Another excellent video, and nicely done safety upgrades, capacitor upgrade, and restoration!
About ten years ago, I purchased a box of old items from an estate auction at a farmhouse in Wagontown, PA. Inside, I found a payment book and catalog from " The National Farmer's Grange League", which sponsored community halls across most of the United States. They sold Aetna, Halson, and Westinghouse radios through that catalog, which also carried Cooper Tires, Rexall animal medications, canoes, Mossberg rifles and shotguns, husbandry supplies, and even Minneapolis-Moline tractors. I saw a notation which stated that Sears- Roebuck provided the warranty service for everything electrical. I remember that the payment for one of the radios listed (in 1936) was 0.35¢ per week, and that "seven cents of each dollar that you spend profits your Community Grange".
Great repair video! I learn something new from your videos every time. Thanks Bryan!
baretter valves we call them, they look just like an old style lightbulb, very cool looking!!!
For sets with just a few 300mA tubes: with the rectifier diode method you can add a resistor in series with it to get the filament supply voltage down to where it should be for the series string of tubes.
I truly enjoy all of the videos you have done and am amazed at the ease you seem to have solving problems. Perhaps one day you might show us just where you are hooking your probes/leads up to while taking your measurements, not just with the voltages, but also when connecting signal generators or oscilliscopes. I haven't had a great deal of experience with test instruments, but it is obvious that you have and I'd really like to benefit from your experience. Thanks for another great video.
Best 73's~N4TYX~Ed Allen
You are the man, Bryan! Really good video and repair.
Would there be enough room for a 12.6 volt center tap transformer in there? Put the 12 volt filaments across the entire secondary and the 6 volt filaments across the center tap.
Great commentary. I enjoy watching your video's. Keep up the great work.
For the voltage dropping capacitor it is good practise top put a 1 or 1.5 Meg ½ or 1 Watt resistor across its terminals, to discharge the Cap when the radio is turned off.
Great informative repair and problem solving on the input voltage.
Jim
A good source for A-C capacitors is ceiling fans, these are used to control the speeds. They also work great for filament strings such as this.
Real interesting repair. Very cool on the resistant comparison.
Thanks
Carl
that is a pretty radio.
I wonder if you use some heat sink compound on the back of the power resistor when you mount it on the chasis ,if that would be a little extra help.to.transfer more heat to the radio chasis ?
+Ron Thompson - The problem is that the chassis is small and trying to use it as a heat sink would bring it and the cabinet to undesirable, possibly dangerously high temperatures.
A fuse could be added in series with the capacitor and tube filaments, to protect the scarce vintage tubes if the capacitor fails in a short circuit mode. After warm up, the filament current is rated at 0.3 A. When the tube filaments are cold, their resistance is lower, but the capacitor will limit current. I estimate peak current under 0.4 A and suggest a 0.5 A fuse in series with the filaments and capacitor.
Usually, one side of the line cord connected through the switch to the chassis. I suggest a polarized line cord with the switch rewired: neutral conductor tied directly to the chassis and "hot" conductor wired through the switch. Better yet, use a GFI plug and cord scavenged from a second hand store hair dryer. This cord is also polarized and should be wired at the chassis the same way as for non GFI but polarized line cord.
The idea of using a cap to drop heater voltages is an excellent approach to making these old “junker” radios play again safely. Still receives many stations considering it is only a TRF circuit. Using an RF sensitivity control in stead of an AF volume control is really old tech even for the 1930s. Was the builder of the set trying to save a buck by not employing AVC ? That would have required paying a licensing fee for the application of AVC . I am always curious about who actually built these “jobber” sets. I know that Aetna ( Walgreens ) often used Simplex Mfg out of Sandusky , Oh. Simplex even built some sets for Philco including portables and Auto radio’s until Philco bought them out...
Can the capacitor be used on transformer operated radios too? Just to make the transformer a little happier from all the heat it puts off or do i have other problems. I restored an Arvin 417 (Noblitt Sparks) and after a couple hours,the transformer is real hot to the touch. No known shorts in the set in any of the stages. All caps replaced too..
Fairbanksmorse2014 You might have a bad transformer-!!
I just bought a 1941 Pilot model B 1 with a line cord that has a resistor built in.It will be here next week;I got it off of ebay.Should it be bad,I'll know how to replacement.Thanks again for the video.Any info is greatly appreciated.
I have a Aetna Radio like this need help with new caps and resistors mine are missing can we make contact
Great Job! I'd be willing to bet that radio was made by a company named Detrola here in Detroit? They made a lot of those "House Brand" radios, for just about everybody. Keep up the good work. Brendan
I was watching your repair video and you indicated there was a electronic parts supplier named Miles of Myles you like to purchase parts from, especially the resistors for resistance cord replacement. Can you repost the website for the supplier?Thanks
+Michael Wilson - If you still don't have an answer he was referring to Mouser Electronics.
Very interesting video! I didn't know Walgreens had a store brand radio back then. In the 90's their house brand radios were Tozai that were made in....guess?
Interesting radio. I see one on ebay with the line cord removed and no mention of the line cord resistor... I hope no one gets it and decides to slap a regular cord on it...
Hank Hill, I thought a capacitor stores electricity up and then discharges it all at once, how can you make it function in place of a resistor?
It only works if the frequency is reliable and you know it. The reactance, X (in ohms) is 1/6.28FC, so C is 1/6.28FX. You can use Ohm's law to calculate voltage from current or current from voltage, BUT the voltage is "imaginary", so you either have to use sines and cosines or phasors to add it to other voltages in the circuit. In this case, since the phase angle is -90 across the cap and 0 across everything else, you can fit them into the formula for a right triangle (see my hack above). All these calculations only work as stated for a clean sine wave; the cap will still drop voltage reliably for a square wave or a sawtooth, etc. , but the math would be much more complicated and trial & error would probably be easier than figuring it out.
America First The capacitor only works for A.C. voltage- depending on the frequency of the voltage, and the size of the capacitor, the A.C. current can be controlled.
My mother was born in 1935 so this radio is as old as she is. I've heard my father say many times that it was common when he was a kid that many radios were run on batteries and he was born in 1928.
Greetings:
To avoid all of that wasted heat, you can substitute a 12-15 uf 200v capacitor.
Those ballast tubes get as hot as a soldering iron. I burned myself a few times on one of those
Good repair, and thanks for the very good clear explanation of the series heater chain and the options you have for repair. Here in the UK you have to drop a lot more volts and the big chassis mount resistor is the norm in AC/DC sets, horrible things that get very hot and are often found to be open when you get the set. Some of the guys here replace them with capacitors but like you, the math is a mystery to me!! Incidentally, why did they bother with a TRF when with 4 tubes they could have had a simple superhet with better sensitivity and selectivity? Just to save the cost of 2 IF transformers I guess.
I read somewhere that in the '50s and '60s they imported some "AA5" radios that were designed around 120 volt mains to the UK from the USA or Japan, with added "curtain burner" cords to drop the remaining 110 or 120 volts. I've always wondered how those fared and what people did with them when the cords failed.
I had a discussion with a fellow on one of the forums about the dropper diodes. I suggested using the 3 amp type rather then the usual 1 amp 1N4007 types, and to use two in series if one were going to go with the diode dropper method. He insisted that it was unnecessary using 3 amp diodes since the filament only draw 300 ma, and that two in series was unnecessary for the same reason. So I asked the rhetorical question, which is cheaper, buying a new set of tubes at between $1 to $10 each, or spending an extra $.20 on better diodes and using an extra diode?
Point in fact I don't like the diode dropper method at all, BandersenTV ran some experiments with each dropper type on a series string T.V set. First, you usually need a combination of a diode and a resistor since the diode seldom drops exactly what you need. Second, the diode droppers are instant on, there is no cushion for the tubes to warm up, so you really need a current limiting device in series with the string. He found that the capacitive dropper was probably the best for soft starting the tubes, but as with the diode it's hard to get the voltage exactly right without using a resistor in combination with it.
You are right about the peak to peak voltage with the diode I think, which is why you really need to use some formulas to calculate how much drop you are going to get and how much you need to add rather then a using a VOM.
+OlegKostoglatov - I'm coming in a little late on your post but the thing about the diode solution is that they only provide a fixed "average voltage" from the line and as you mentioned, will almost always need an additional component to tailor the voltage to what is needed. As I recall from my electronics math, the average value of the half wave pulsating DC voltage that results is equal to the peak voltage x 1/Pi, which for 120v comes out to 38 volts and change--actually less than what is needed. This actually makes sense since, as you know, the diode method was used extensively in tube sets to provide the instant on feature. I do remember seeing how much fainter the tubes glowed when such sets were "off." So in reality, the diode method would not work for this application.
[EDIT]: DOH! Little mistake in my figures. I used the RMS value for the line voltage instead of the peak value. The actual answer comes out to just under 54 volts. Again, still less than what is needed. My bad.
I'm fairly new to the hobby and can't say that I know a whole lot yet, but I'm wondering why a transformer wouldn't be a better choice if one of the right value could be found.
One thing to remember, is that in a SERIES circuit, the individual tube heaters can be all different VOLTAGES, but ALL of tube heaters MUST draw the same CURRENT.
Very good lesson, thank's for this video!
Correct me if I'm wrong, but with the volume switch in the antenna circuit gain would suffer at a lower setting and weaker stations would fade out
i sucked at math formulas too!!! maths is my weakness, we had a general fornulae sheet which helped!!
It appeared that you were pointing to an electrolytic capacitor and saying it was across the line. If so, it really shouldn't be an electrolytic but a safety cap...in fact, regardless of what it was, it should be a safety cap.
A curtain burner. I used to have one.
you would wire the diodes in parallel wouldn't you, so that if one diode failed the other diode would pick up the load like the alternator in a car can do
+I Eat What I Grow - No. They would be in series, so that if one shorts the other would still be in line rectifying the heater current. At least that's the idea.
The diode doesnt work, just like you see it glows too bright. I would like to see the difference in wattage consumption between the cap and the resistor. Should be half
I know. The way to do it is Mylar wiring, and two ceramic resistors in series. Shango I can show you how to use this method, if you wish. Then a long antenna wire, and always unplug the device later, don't depend on the pot. Get a Chinese power strip or something ok?
Lol!!!! Steven
8:15 I think I can hack my way around most of the complex math, though maybe the nostalgiaar people beat me to it. With the same .3 A current and 62 "real" volts across the rest of the string, the voltage across the capacitor will be "imaginary" (90 deg out of phase), so they are like 2 legs of a right triangle with a hypotenuse of 120. So 120 squared minus 62 squared is 10,556, the square root of which yields 103 V. 103 V/.3 A is 343 ohms reactance or X. With C = 1/6.28FX, we get 7.73 MFD, which is a little less than the 10 MFD that was a little too big (18:08). That might save someone from having to order more than one cap.
Good repair thanks for Sharing (its Jeremy James from facebook)
I enjoy your videos. Could you make a guitar amp repair video sometime? Preferably a Marshall or Fender tube amp. There's lots of schematics available.
8:52 Welcome to the club!
PS. Thanks for all the great videos.
I have learned a lot.
Use 60 lb test fishing line. It will outlast dial cord and is cheaper and easier to obtain
May I ask were you went to school,for all your electrical know age. You are really good at what you do with old radios,,the rweason I like tube radios is the sound.its better
Nice. Are you keeping that set?
Capacitors and diodes can short. I would have used the metal cased resistor or a ceramic resistor. I wasn’t any good with the math and formulas either. No problem with ohms law formulas. Ran into problems in R C circuit formulas
never knew of these lesds!
In another section of the last of the 4 links you provided, they have all the ways of calculating various voltage dropping schemes and they have an Excel spreadsheet developed by Paul Stenning that you can download free to do the maths for you. Google: "dropper calculations spreadsheet" It includes the resistor, capacitor and diode methods -and a few combinations to boot.
TRF's can be very sensitive and selective, but design is everything. I homebrewed a VHF only TRF receiver that is more sensative and selective than any of my modern VHF radios, or any of my 3 SDRs for that matter.
you can use two resistors in parralel, both twice the value of the one you have (half the power over one of the two resistors, is less heat!) but the cap is the best idea!
My father used to get real pissed off, when I would turn the volume up to find a station...
I have a similar style radio to deal with at the moment. I have already purchased some of the Racol resistor for testing purposes but I may use a diode half power or capacitive dropper. I haven’t decided yet it will depend on the dissipation within the radio cabinet. Unfortunately it more of a problem for me in the U.K. as we have a 230 volt supply. If you fancy a quick look I have included a link but it’s not your normal repair video ua-cam.com/video/GRYLdkwXzpI/v-deo.html. Thanks stay safe my best regards Chris
I would have gone with the power resister mounted with some heat sink paste and let the chassis dissipate the heat
stick with resistors