Ahh, I built that exact radio in college around the time you made this video and I'm brushing up for a job interview tomorrow. Incredibly useful, thanks for your upload!
Love that radio! I ran a college level class on radio and used that model as a basis? Each student built their own kit, then learned trouble shooting of wiring errors. Once the radio was finished they learned how to align the IF circuit and front end tuning. Then the fun began as I gave the each three different bugs to find. All enjoyed the class and it was my favorite criteria. In the second semester we built a complete Theremin.
The signal tracer I use in my mind and a simple oscilloscope. Having other tools like a C meter, voltmeter and ohmeter were all I had when I made a living in radio repair. Alignments were not necessary , and most problems were repeatable factory and design fuck ups. Better tha fancy equipment was a good parts supply and a tube tester. A new tube is more likely to fail before one that has been in operation and proved its worth. New tube had a higher confidence level and peace of mind. You know that feel good emotion. The markup on tubes was very profitable as well. The customer was given a false sense of security too, know the radio needed an affordable part. I never threw out an old tube. The first offering was back to my customer. If they refused then the tube went in my supply of known good but maybe weak tubes, to be used as tools. I never resold an old tube as a new one.
Dear tomtektest, I am building one of these kits right now. I have just completed the AM section, I used the Eico 324 signal generator and a Heathkit audio generator to modulate the 455 KHz at 400 KHz to do an alignment. The AM section operates very well. I did not understand how to use a signel tracer but this video cleared up a lot of questions I have. Thank you kindly for this video, it was most helpful...
Wow! I have a feeling I'm going to learn very much from you. Having read Joseph J Carr's book on repairing antique radios, I did possess a knowledge of how a super-het radio works, but I have no knowledge of signal tracing. This video is clearing away the confusion and your explanation is nothing short of excellen t. THANK YOU ! And yes . . . I did subscribe!
Awesome video. I've been trying to lean more on using my Tenma tracer/injector (same model as this) so I can be more effective and efficient on diagnosing issues with guitar amplifiers and other various audio equipment. I'm also trying to be more mobile so as to make it easier on the clients in the event they can't transport their equipment. Because this model runs on a 9v battery and is an all in one unit, essentially... It makes things a lot easier because it is so compact. Many people would say that an oscilloscope is a better tool for my realm, and it probably is. But, if I'm mobile and not on a test bench, this thing becomes super handy and essentially allows me to isolate any given issue even if I have to use process of elimination based on problems I know aren't presented on any given amplifier. This video really does demonstrate how useful these devices can be. Thank you for the upload!
Hi First time viewer, This video is just excellent, I just built one of these kits and I must say you have done a great job at explaining how to use a signal tracer, thank you kindly for this video it has become a great help to me.....
11:26 Thank you for that explanation. I could not understand how an AF injector would work in the RF section. Now I know it is due to the harmonics it generates.
Wow, one of the best videos I've seen on the topic, thank you for such a clear explanation. Sadly people sell those old signal generators as if they're made out of gold but I just purchased a TinySA. Also just subscribed to your channel as I see plenty of other interesting material :)
They do go for big bucks, but honestly I wouldn't mind spending some coin all over again on this particular Tenm. It's paid for itself many times over in my case and is such a great little tool to work with. I've thought about cloning and selling them on eBay but the amount of work to make one would mean I'd have to charge almost as much as what these go for to make it worth it. Wish there was something I could incorporate into the design to make it a worthy purchase for people.
Thank you so much for the input, I just though that because you can dial in 10.7MHz on the 324, it is still AM signal, so now I understand what you are saying. I have noticed that when I set the Eico to 10.7mHz and connect the RF output to TP A, I can hear that signal through the speaker, this is a very interesting point... Again great video, and that was so interesting that you worked at a shop that really used this vintage equipment.... Take care and enjoy your weekend....):
I enjoyed your video using the Tenma 72-540 signal tracer....I ended up buying one...with no test leads. I have been combing the internet for a schematic..hoping to find out if the leads have a resistor in them. Can you give some insight? Kevin Urquhart Grimsby Ontario Canada
Great video, I have a kit like that I need to finish. Could you do another and show how to do align the if and s curve with your sencore sg 80 and test sensitivity. Thanks Jimmy Alabama
I have considered a similar thing for some time and it is certainly on my list. Right now I have a lot to do before fall on other things so I do not know when I will get to that but I will try to move it up on my list. I would prefer to use a vintage (1960-1970's) FM tuner for the alignment demonstration though because I feel that would be of more use to more people. I would also like to include Stereo alignment in the same video. I found the alignment instructions in the Elenco manual straightforward, with or without test equipment (it is nice they included both). Since the resulting receiver is not intended for HI-FI use, the alignment is not as critical as in other receivers, especially Stereo or wideband HI-FI receivers, so I just did it "good enough" on the Elenco. I will, of course continue to think about this until I actually get around to an FM alignment video so comments and suggestions are always welcome.
Great video mr. i just received this tracer from a friend was given to me but he didn’t have the probes and no manual.can you tell me how to build or buy a new probes for this test equipment.it would be well appreciated.
I think Elenco has discontinued its kits but they are still available on Amazon (I bought 3 from Amazon after Elenco announced the change.) I think Elenco transferred its remaining inventory to an Amazon warehouse so, to the extent that inventory remains, they are available there. I just checked Amazon and the AM/FM kit is still available for $39.69 as well as some others.
Wanted to ask you a question, the FM section does not work, I checked the transistor voltages and they are OK, The fm section will pass a 10.7 MHz signal, however, no output at all, and ideas. I am using the vintage Eico 324 modulated with a 400 KHZ tone. Completely dead... Any ideas???
Your question rang a distant bell with me. I worked in a Radio-TV shop in high school (1960's) and ran into the same issue. The EICO 324 will only generate Amplitude Modulation (AM). To get a signal to pass through the FM detector, it must be Frequency Modulated (FM). In fact, the FM detector is designed to reject AM. I still remember my red face when the shop owner explained this to me after I spent a whole evening trying to get an AM signal through an FM radio. If you have a function generator that can produce 10.7 MHz with FM modulation you will be able to use that to align the IF amplifiers. To test the FM Converter (Oscillator/Mixer) will require a true FM generator like the Sencore SG165 since most function generators wont go to 108 MHz. If you have access to a scope and a demodulator probe, you can use an AM Generator to align the IF stages by watching the demodulated AM at the input to the FM detector. If you don't have an FM generator or a scope, you might want to re-read the manual section beginning with "FM Final Alignment" (on page 36 in my manual) and continuing with the next page entitled "Alignment with no Test Equipment." Hope this helps and welcome to the club.
Tom, why does it look like the IF transformers are stepping down the signal with the schematic showing the higher number of turn on the left and the smaller number of turns on the right?
IF transformers for transistors must have a step down turns ratio to match the higher impedance of the output to the lower impedance of the following input. With tubes or FET transistors, the opposite is true and the output impedance is lower than the following input impedance so the turns ratio is low to high in those circuits.
Thanks Tom! I'm been learning on tube gear and when I watched your video light night I was confused by the schematic. Again just learning...so does that mean that the subsequent input would attempt to draw too much current from the preceding output if there wasn't a transformer there to limit impact on the preceding circuitry?
Actually it is about efficiency - when a stage is driven by its input impedance it is more efficient. Similarly, when a stage is driving its output impedance it is more efficient. So, transformers are used to make the preceding stage see its output impedance and the following stage see its input impedance. You can think of it in terms of current and voltage if you remember that impedance is just the ratio of voltage to current.
So the output of the preceding stage is generally going to be higher in voltage, lower in current than the subsequent stage. IE the subsequent stage is looking for more current (power?) and less voltage as it will then provide additional amplification to that input? If this is incorrect, perhaps you could dust off an analogy for me to better understand this concept.
I think the best approach is for me to refer you to some basic electronics text. I used Basic Electronics published by the US Navy in 1955 - it can be found online by searching for "basic electronics navy pdf". There are many others but I know this one is non-mathematical (it is also dated but that might be good since you are interested in tube circuits as well). The sections you might look at first are those on transformers and tuned circuits. I also suggest you try to find a local mentor (perhaps through a local ham club or trade school). I am sure that you realize that trying to convey large quantities of information by question and answer in RUclips comments is very inefficient and best used only to cover specific questions directly related to the video. If you prefer to use RUclips videos instead of a text, you might search for the same topics mentioned above.
Tony, here it is, about five different manufacturers made this tester under licence and it was like looking for a needle in a hay stake to find a manual......www.qsl.net/k/k0ff//017%20Manuals/Tenma/72-540%20owner's%20manual.pdf. Regards, Mike. UK.
awesome, thx Theo, much appreciated, that's a great clue to use clone names to find those hard to find manuals ... have you come across a service manual as well, ie, schematics, troubleshooting, component list ?
Came for the Tenma, stayed for the entire lesson, ordering a radio kit immediately, thank you so much!
Ahh, I built that exact radio in college around the time you made this video and I'm brushing up for a job interview tomorrow. Incredibly useful, thanks for your upload!
Love that radio! I ran a college level class on radio and used that model as a basis? Each student built their own kit, then learned trouble shooting of wiring errors. Once the radio was finished they learned how to align the IF circuit and front end tuning. Then the fun began as I gave the each three different bugs to find. All enjoyed the class and it was my favorite criteria. In the second semester we built a complete Theremin.
The signal tracer I use in my mind and a simple oscilloscope. Having other tools like a C meter, voltmeter and ohmeter were all I had when I made a living in radio repair. Alignments were not necessary , and most problems were repeatable factory and design fuck ups. Better tha fancy equipment was a good parts supply and a tube tester. A new tube is more likely to fail before one that has been in operation and proved its worth. New tube had a higher confidence level and peace of mind. You know that feel good emotion. The markup on tubes was very profitable as well. The customer was given a false sense of security too, know the radio needed an affordable part. I never threw out an old tube. The first offering was back to my customer. If they refused then the tube went in my supply of known good but maybe weak tubes, to be used as tools. I never resold an old tube as a new one.
Thank you and appreciate your effort. Greetings to you from Turkey .
Thank you for sharing your knowledge. I am currently putting this kit together and explaining how the test equipment operate is a big help.
My main RF generator is the Eico 324 I also have the Eico 147A signal tracer, these are my favorite to work with...
Excellent explanation of what has become a lost art!
Just the video I've been looking for, thanks for sharing you knowledge and I look forward to learning from your other videos.
Dear tomtektest, I am building one of these kits right now. I have just completed the AM section, I used the Eico 324 signal generator and a Heathkit audio generator to modulate the 455 KHz at 400 KHz to do an alignment. The AM section operates very well. I did not understand how to use a signel tracer but this video cleared up a lot of questions I have. Thank you kindly for this video, it was most helpful...
Wow! I have a feeling I'm going to learn very much from you. Having read Joseph J Carr's book on repairing antique radios, I did possess a knowledge of how a super-het radio works, but I have no knowledge of signal tracing. This video is clearing away the confusion and your explanation is nothing short of excellen t. THANK YOU ! And yes . . . I did subscribe!
Thank You Sir , I appreciate your knowledge and delivery - blessings to you and yours
Outstanding presentation and lesson. Thank you!
Awesome video. I've been trying to lean more on using my Tenma tracer/injector (same model as this) so I can be more effective and efficient on diagnosing issues with guitar amplifiers and other various audio equipment. I'm also trying to be more mobile so as to make it easier on the clients in the event they can't transport their equipment. Because this model runs on a 9v battery and is an all in one unit, essentially... It makes things a lot easier because it is so compact. Many people would say that an oscilloscope is a better tool for my realm, and it probably is. But, if I'm mobile and not on a test bench, this thing becomes super handy and essentially allows me to isolate any given issue even if I have to use process of elimination based on problems I know aren't presented on any given amplifier.
This video really does demonstrate how useful these devices can be. Thank you for the upload!
Tom, Subbed. Great channel and the way u describe stuff, like we are not dummies. Good thought process also. Point
Hi First time viewer, This video is just excellent, I just built one of these kits and I must say you have done a great job at explaining how to use a signal tracer, thank you kindly for this video it has become a great help to me.....
Well, yes. I do look forward to a continuation of this topic.
11:26 Thank you for that explanation. I could not understand how an AF injector would work in the RF section. Now I know it is due to the harmonics it generates.
Tom, I'll look forward to a continuation of this topic soon please
Wow, one of the best videos I've seen on the topic, thank you for such a clear explanation. Sadly people sell those old signal generators as if they're made out of gold but I just purchased a TinySA. Also just subscribed to your channel as I see plenty of other interesting material :)
They do go for big bucks, but honestly I wouldn't mind spending some coin all over again on this particular Tenm. It's paid for itself many times over in my case and is such a great little tool to work with. I've thought about cloning and selling them on eBay but the amount of work to make one would mean I'd have to charge almost as much as what these go for to make it worth it. Wish there was something I could incorporate into the design to make it a worthy purchase for people.
wow keren mbah, kimutan jaman smp ngraket radio am super heterodyne
Thank you so much for the input, I just though that because you can dial in 10.7MHz on the 324, it is still AM signal, so now I understand what you are saying. I have noticed that when I set the Eico to 10.7mHz and connect the RF output to TP A, I can hear that signal through the speaker, this is a very interesting point... Again great video, and that was so interesting that you worked at a shop that really used this vintage equipment.... Take care and enjoy your weekend....):
Tuning slightly off frequency makes AM modulation easier to hear through FM detector.
I have an old tracer made in 1949 I want to restore and will use it.
I enjoyed your video using the Tenma 72-540 signal tracer....I ended up buying one...with no test leads. I have been combing the internet for a schematic..hoping to find out if the leads have a resistor in them. Can you give some insight? Kevin Urquhart Grimsby Ontario Canada
Great video, I have a kit like that I need to finish. Could you do another and show how to do align the if and s curve with your sencore sg 80 and test sensitivity. Thanks Jimmy Alabama
I have considered a similar thing for some time and it is certainly on my list. Right now I have a lot to do before fall on other things so I do not know when I will get to that but I will try to move it up on my list. I would prefer to use a vintage (1960-1970's) FM tuner for the alignment demonstration though because I feel that would be of more use to more people. I would also like to include Stereo alignment in the same video. I found the alignment instructions in the Elenco manual straightforward, with or without test equipment (it is nice they included both). Since the resulting receiver is not intended for HI-FI use, the alignment is not as critical as in other receivers, especially Stereo or wideband HI-FI receivers, so I just did it "good enough" on the Elenco. I will, of course continue to think about this until I actually get around to an FM alignment video so comments and suggestions are always welcome.
I need to find a cheap signal tracer,that I can use for tube radios ,but I havent found any such item .
Just bought the same Temna on ebay this a.m. Brand new in the box never used. Includes everything except owners manual. Do you have a copy?
Thanks!
Does the probe have any circuitry? Or components in it?
Anyone know?
Thank you
Thanks for the vedio. I want to buy a tube tester by which you can advise me an old tester and which brand or a curve tracer like utracer3, etracer .
Great video mr. i just received this tracer from a friend was given to me but he didn’t have the probes and no manual.can you tell me how to build or buy a new probes for this test equipment.it would be well appreciated.
HI Tom,,, thank you for the interesting and informing video,, I'm wondering if the Elenco radio kits are still available these days?
I think Elenco has discontinued its kits but they are still available on Amazon (I bought 3 from Amazon after Elenco announced the change.) I think Elenco transferred its remaining inventory to an Amazon warehouse so, to the extent that inventory remains, they are available there. I just checked Amazon and the AM/FM kit is still available for $39.69 as well as some others.
Wanted to ask you a question, the FM section does not work, I checked the transistor voltages and they are OK, The fm section will pass a 10.7 MHz signal, however, no output at all, and ideas. I am using the vintage Eico 324 modulated with a 400 KHZ tone. Completely dead... Any ideas???
Your question rang a distant bell with me. I worked in a Radio-TV shop in high school (1960's) and ran into the same issue. The EICO 324 will only generate Amplitude Modulation (AM). To get a signal to pass through the FM detector, it must be Frequency Modulated (FM). In fact, the FM detector is designed to reject AM. I still remember my red face when the shop owner explained this to me after I spent a whole evening trying to get an AM signal through an FM radio. If you have a function generator that can produce 10.7 MHz with FM modulation you will be able to use that to align the IF amplifiers. To test the FM Converter (Oscillator/Mixer) will require a true FM generator like the Sencore SG165 since most function generators wont go to 108 MHz. If you have access to a scope and a demodulator probe, you can use an AM Generator to align the IF stages by watching the demodulated AM at the input to the FM detector. If you don't have an FM generator or a scope, you might want to re-read the manual section beginning with "FM Final Alignment" (on page 36 in my manual) and continuing with the next page entitled "Alignment with no Test Equipment." Hope this helps and welcome to the club.
Tom, why does it look like the IF transformers are stepping down the signal with the schematic showing the higher number of turn on the left and the smaller number of turns on the right?
IF transformers for transistors must have a step down turns ratio to match the higher impedance of the output to the lower impedance of the following input. With tubes or FET transistors, the opposite is true and the output impedance is lower than the following input impedance so the turns ratio is low to high in those circuits.
Thanks Tom! I'm been learning on tube gear and when I watched your video light night I was confused by the schematic. Again just learning...so does that mean that the subsequent input would attempt to draw too much current from the preceding output if there wasn't a transformer there to limit impact on the preceding circuitry?
Actually it is about efficiency - when a stage is driven by its input impedance it is more efficient. Similarly, when a stage is driving its output impedance it is more efficient. So, transformers are used to make the preceding stage see its output impedance and the following stage see its input impedance. You can think of it in terms of current and voltage if you remember that impedance is just the ratio of voltage to current.
So the output of the preceding stage is generally going to be higher in voltage, lower in current than the subsequent stage. IE the subsequent stage is looking for more current (power?) and less voltage as it will then provide additional amplification to that input? If this is incorrect, perhaps you could dust off an analogy for me to better understand this concept.
I think the best approach is for me to refer you to some basic electronics text. I used Basic Electronics published by the US Navy in 1955 - it can be found online by searching for "basic electronics navy pdf". There are many others but I know this one is non-mathematical (it is also dated but that might be good since you are interested in tube circuits as well). The sections you might look at first are those on transformers and tuned circuits. I also suggest you try to find a local mentor (perhaps through a local ham club or trade school). I am sure that you realize that trying to convey large quantities of information by question and answer in RUclips comments is very inefficient and best used only to cover specific questions directly related to the video. If you prefer to use RUclips videos instead of a text, you might search for the same topics mentioned above.
Can you use one of these signal tracers to check for a channel that is out on a reel to reel? Anyone know?
Thank you
Most definitely
@@3dsmaxrocks699 thank you for replying back
more
tenma = ooooooooooooooooooooooooooooooono
where can the tenma pdf manual
be found ?
Sorry, I don't know if one exists and, if so, where it might be found.
Tony, here it is, about five different manufacturers made this tester under licence and it was like looking for a needle in a hay stake to find a manual......www.qsl.net/k/k0ff//017%20Manuals/Tenma/72-540%20owner's%20manual.pdf. Regards, Mike. UK.
awesome, thx Theo, much appreciated, that's a great clue to use clone names to find those hard to find manuals ... have you come across a service manual as well, ie, schematics, troubleshooting, component list ?