Hello Tony!! It's impressive to see so much dedication to how these things were done in the past. And even more impressive is to see your work. Congratulations!!!
This was such a pleasure to watch. With all of the negative things in the world right now, and the negative uses that the Internet can be put to, seeing someone with a passion for their subject take the time to pass on their knowledge in such a calm and honest way is truly inspiring. Thank you Tony, these videos are sincerely appreciated and the effort that goes in to making them is not taken for granted.
Besides being an excellent electical engineer (or whatever you are, x-ray) you are an outstanding pedagogue. Your employees are fortunate to have an employer skilled in both fields.
Your vids are so amazing Educational content is so rare these days. So agree with your comment about "show them how but don't give the answer." Give a starving person grain and by next week they are starving again. Give a person a spade, land, grain & education on how to farm will never go hungry. Thank you for making these vids.
Tony, everytime when i see you on your new video i almost have tears in my eyes and i feel like I have met someone close after years of separation. Thank you for everything and God bless you.
Working on a "The Fisher" 500-C receiver from 1963 with the optional MPX adaptor for FM stereo. This unit has the best consumer equipment assembly quality and solder joints I have seen outside of military and medical equipment. I worked for Physio Control building medical equipment, and for the Navy building torpedo fire control systems and torpedoes. Love the refresher course back to the days of my electronics training, inspired me to get out my old training manuals and brush up on math and theory I had forgotten about. Remember ELI the ICE man? Left hand rule?
I agree, you should put in NP0 (that is "n-p-zero" for the people to order) caps to minimize drift due to thermal effects. Putting in an I.F. can with the adjustable ferrite cores in the mid position, then determining the CORRECT FREQUENCY of the I.F. chain (for example, cans from the early days when people tried to avoid paying RCA for their 455 KHz design which was patented) you could end up with the correct capacitance by using a formula. By the way, most schematics don't show different coils inductance. You would have to VISUALLY mark the direction of the can in the circuit. If the leads are color-coded, all the better. Replace them any time if you can! Good luck! Get rid of any bizarre caps such as disc ceramics in the oscillator circuit to make it stable by using silver micas.
5:28 It'd be a wider sweep than that, as AM signals get up to 5kHz. As such, the sweep range is probably more like 440kHz to 470kHz, to give a good 15kHz either side of the IF frequency.
50+ years ago (in my pre teens), I thought this stuff just may be my calling. However, a capable knowledge base, and outlook for this as a career was unfortunately lacking. Although I did go to technical schools, etc, and (usually) successfully did some of this work, I chose to go with oil & gas, then telecom (phone company), as a good living. Fast forward 50+ years, now retired, have struck gold (or oil gusher), with your channel .. much thanks Tony ...
Nice video once again Tony thank you,I like when you give out the little tech tips in most of your videos, for instance when you mentioned the starting points value for those IF capacitors
Thanks to vintage pieces, the repair business lives .. as with appliance/outdoor power equipment ,etc., the margin of what the customer is willing to pay to repair vs buying new is quite slim. This leaves the one man show/hobbyist, a good chance of acquiring vintage/rare pieces for little/close to nothing/or even free, and coming up with some very cool, desirable stuff ...
Thanks Tony, enjoyed the video. First tube tuner I worked on was a Zenith add on for a consolette, it sounded like it was in the middle of a thunderstorm on am and fm from one end to the other. Replaced all the silver mica caps, works great now.
I believe that the stages in any I.F. Have different Q on each stage to prevent self resonance through the radio, which would be why very similar coils have different part numbers. Also sometimes the peaks are slightly offset from each other for the same reason, and to slightly broaden the bandwidth.
Sorry Tony for overdoing it with commenting .. but, back during the 60s .. we had this White plastic case GE tube radio, bought brand new circa 1962 .. (BTW the brown/maroon radio in the foil capacitor video is a near dead ringer) mom placed it on top of the refrigerator, and played it all day every day until (supper time), for approx 10 years until about ‘72 .. all it would do is “crackle”. I was in a TV repair shop course when a Sr in HS. I asked my instructor about it, and he said “the IFs” (I had already tried testing/swapping tubes at the local drug store). Anyhow, prior to, I tried to keep it around, but somehow mom found it and threw it out before I could bring it in. Amazing how I recall this like yesterday, 50 years later ...
What a great and timely video Tony! I'm currently working on a 1946 Zenith AM/FM console with one or more bad IF transformers and was wondering how to go about fixing it. You've answered all of my questions. One stop learning. 🙂
Great video. I have the same rf generator. Those old hp generators are great I have the sister function generator also. I have been using these for a very long time no problems
When calculating or empirically chosing caps to suit an IF transformer out of circuit it is worth leaving a few pF out to account for the stray capacity of the circuit the transformer will be soldered back into. More likely to be of benefit with the 10.7 mHz ones. This might explain why with one you reduced one cap from 30s to 20s pF
My late dad told me it's not just to learn but learn how to learn. IF means intermediate frequency not intermodulation. It's an in-between you could say like a gear. Great job.
Thanks Tony for the great video. I have dealt with some of these Miller type transformers as well. I appreciate the information on calculating the capacitor value because I have been using the Shang066 method. This method is much more precise. I do have one tip for you however lol. Instead of using the dremel with a burr to remove the rivet, use a sharp drill bit just smaller than the diameter of the rivet. Either in a pin vise or on low speed with a drill. Much more control over popping that outer portion of the rivet. Thanks again!
I have had some bad experiences with the drill bit method. Some folks are really good at it, but I'm not one of them! I like the control I have with the Dremel. Perhaps when I'm done with my therapy sessions from the past experience, I'll give the bit-method another try ;)=)
Tony, You hit a KEY NOTE in your video about diagnosing a problem and using ANALYSIS! to figure out a solution. Well that is something you learn in school. School just enables that ability for someone to realize and utilize and hone in on those skills. For some people it takes longer to do cause they don't have the skills, or most importantly experience and skills, cause those two ingredients is what provides possible solutions. This is true in most of the engineering and sciences. There are some people that just dont have the skills to do analysis and diagnostics.
I noticed I said that after I processed the video. I didn't feel like reprocessing it, so that's how it got uploaded. If that's the only mistake I made. then I'm thrilled. I got silver mica disease from looking at this stuff for so long! ;)
@@xraytonyb LOL... You caught Intermodulation Distortion Disease eh Tony? I heard that RF "distancing" will cure that problem... Or you can just isolate yourself inside a Faraday cage and recover that way! Thanks for the great video and detailed explanations Tony.
...if anyone is interested, I'd suggest using silicone lubricant instead of graphite because: 1- graphite is an ELECTRICALLY CONDUCTIVE substance, and 2- silicone lubricant is good for dry, brittle plastic-(!)
I usually have an eagle-eye for typos so I’m surprised I just noticed the one in your introductory warning. The “their” in “at their own risk” is spelled thier. Also, IF generally stands for Intermediate Frequency, I haven’t heard it called Intermodulation Frequency as you stated in the video. Sorry for the nitpicking, absolutely love your channel!
Shango066 is very good at bringing radios and tv's back to life, he gives the impression that he is not an expert. He is an expert in his own field, clever and a sharp mind :-D I love his sarcastic comments, so dry, he takes no prisoners lol. Like yourself, he is very enjoyable to learn from :-D
YES! 3:13! Every friggin' day, I have this conversation at work. Usually with the same guy.... I have to follow this guy all the time and fix what he didn't.... ARRGGGGG. Sorry. Sorry, I am sure we have all been there and someone probably felt that way about me at one time, but..... ugh. I feel much better now. Thank you.
if i understand those transformers corectly very similar devices are used in old rc toys only instead of magnetic transfer between the coils the signal from first tank circuit is feed into transmiter transistor and then reciever transistor is tuned with another half of the coil and a slug when i was very unexperienced with electronics i was kind of a hack guy and when i got 2 of the same analog rc cars i decided to tune one to a different frequency by randomly swaping coils , slugs and capacitors, and it kind of worked i wish i seen this video 15 years ago :]
Tony, your videos are simply amazing! I wish that you would do a short session on exactly how to hook up the WR-50B sweep function across the IF can to the oscilloscope to get the tracing as shown. It appears that you did this without a ‘ramp’ signal on X axis, and NOT in XY mode? I have been trying to work out any possible such setup for a couple years, and not been satisfied. Videos (and forum threads) just seem to skip to ‘Wa-La!’, there it is! Please consider this! Thanks!
my thoughts but shouldn't you adjust the cores to the center of travel before you measure the inductance of the coil and calculate the capacitor value?? wouldn't this help prevent you from reaching the top or bottom before peaking?
A Quick way to disassemble these transformers is to use a pair of 4.5inch FLUSH cutters cut the top of the eyelet off then you can pry off the metal clamp and plastic part and mica,no drilling or dremel needed, also i am thinking about using smd npo cap or one of those really small axial lead round monolythic types just cut the internal lugs short & solder in the cap and secure in place with some glue, just although i haven't tried this yet.
For me, the dremel seems to give me the best control. I've had the brittle plastic crack a few times when either the drill bit caught or I got a bit too rough with the cutters. It's important to find the method that works best for you. I appreciate you sharing your techniques, as they may be really helpful to others. Thanks for the comment!
...in order to do THAT successfully, you'd need: 1- a sharp pair of "flush cutting" diagonal cutters, 2- a lot of skill, and, 3- more than a little LUCK...
Great job Tony. If you use electrical/physics math formulas, it's much easier dealing with the units in scientific notation. All the zeros can become a overlooked failure point. I can't imagine having a calculator that doesn't use the format.
I should have done a better job when I wrote out the formula. I didn't properly write down the exponent for the frequency and I wrote the decimal instead of scientific notation for the inductance. I'm starting to realize that some viewers really pay attention to everything and if they are just learning, something like that could throw them off. I'm thankful that some of the more experienced folks like yourself are keeping track of these things! I really appreciate it!
@@xraytonyb Not a criticism at all. Just a suggestion. Any new tech's should consider taking the time to learn it. It's really easy and will save you lots of headaches from the old way of using a really long abacus :). We have it so easy now with hand held math machines!
I think that when you measured the capacitance of the first cap your hand was in close proximity to the coil introducing more capacitance. On the second cap that you measured you put the coil down on the bench and completely moved your hand away for a value of 105 pf as opposed to 135 pf value. When measuring very small capacitance values like this even minor variations can make a big difference. Check at 21:38. Stay well. ATB Doug.
You are correct. I did, however, measure these values several times off camera as well. This meter really doesn't seem to be affected a whole lot by capacitive coupling by your hand, unless you are actually touching the leads. This little meter is amazing. It even self-calibrates each time you power it up or hold the reset button. Even my more expensive meters aren't as good with very low capacitance as this one is.
I did one of these receivers a few years ago, some supposed Fisher "expert" was in it before it came to me, a great number of the IF's needed repaired, most of the work was broken/cracked slugs (screwdrivered) I had to find enough of the Automatic Radio slugs from junked transformers I needed 8-10 of them, after I repaired the IF section the FM still wasn't just right turned out someone got into the discriminator coil, inside were two 1.5 meg resistors, the only problem someone put a 1.5k resistor in for one of the 1.5megs. "Expert" yeah right, the owner told me he paid around $500.00 for this "expert" work.
Do you have a sinad meter? Would be a better way of checking the actual sensitivity in a quantitative way, 12dB SINAD is the standard level used as that is considered the minimum for intelligible speech.
Maybe what your experiments show is that it's better to find the correct cap value with the coils back in circuit using a tiny variable. Could save hours of time too.
I've used that method in the past as well, but this was meant more as a demonstration for those who have never seen how these transformers work. Thanks for the comment!
Tony, where would be a good place to source a sweep generator (already have a 2 ch PicoScope) .. I have a vintage Westinghouse H778N7 (in a very cool maple mini maple console HiFi like cabinet), with a SAMS .. looks very similar to your Fisher, that I’m looking at to fix .. PS, it did the classic “worked at first” .. I’m assuming it has the same “itis” and “osis” as the Fisher ...
Honestly I would expect the sweep to be something like 440kHz to 470kHz - you don't want the transformer to be super peaky (ie. a high Q), otherwise you'll lose the higher frequencies of the modulating signal.
I was just picking an arbitrary set of numbers as an example. In most sweep generators, you can adjust the sweep width to whatever you want. On this unit, it is fixed, but I never measured to see what the sweep width was. Sorry for the confusion!
I wonder if you could answer my question in my quest for information about i.f. transformers. I have a 1944 Wireless 19 Set I'm trying to improve reception on as there's not a lot of gain. It works better now after a few adjustments as I heard very little when I first got it. I looked at the i.f. transformers because the cores were jammed solid and could not be adjusted. I think they were adjusted and glued when manufactured which makes sense as they wouldn't want the cores to go off tune when a tank travels over rough ground. I only looked inside the 2nd i.f. and found one capacitor of 140pF and one of 47pF. There was an impression in the wax where I assumed a 140pF had been removed. I wondered why and looked in my radio books, some very technical with complex calculations and some more basic but couldn't find anything. After months of searching the internet I found one reference about changing one capacitor to increase selectivity but it didn't give values. Does it make a higher Q? But wouldn't changing one capacitor throw it off tune as you have demonstrated? An Australian circuit for a 19 Set shows 140pF in both i.f.t.'s. I read yesterday in an old magazine article online the first i.f. is over coupled. It again makes sense to detune things make a deaf receiver because they wouldn't want to listen to Germany when they want to communicate 20 miles. Have you any idea on this? Was the reference to changing one capacitor correct? I never did find anything more about it. I can see a lot of work needed, maybe S-M capacitor disease and resistors gone high, the audio c.w. (Morse Code) filter is extremely bad and not doing much so I'm looking to replace the R's and C's in that, and somehow free the i.f. cores. However, as bad as it is I've had a number of contacts, the furthest being Scotland at about 250 miles but it was hard work on my part to receive him. Bill, G4GHB.
the RCA rf generator is in the sweep mode chanel 1 of the scope is in AC coupling it mesure the amplitude , but how the scope horizontal is set up ? because the ref generator does not have sweep output to drive the horizontal of the scope
...the RF sweep frequency is the 60 cycle line frequency- and an awful lot of oscilloscopes have a "LINE FREQUENCY" setting on the horizontal sweep input(s)...
At 37:13 shouldn't you be using the frequency in Hz not in MHz? Just as C and L are in Farads and Henrys? So like 10700000 and not 10.7? If some of the capacitors in those cans are defective, isn't it safe to assume that the others if not yet defective they will eventually go bad. So their going to need to be replaced sooner or later anyway, so just take all when you are at it?
33pf is typical for the 10.7 if transformers, also Shangos way to find the right cap. value works good EXCEPT you have to be sure the set was never "screwdrivered".
Yep I'm gonna be that guy. If you care about what that bit is called. It's called a burr not a ball mill. If you don't care what its name is, well call it whatever you want bud. Great video as always, enjoyed watching and learning.
I've always wondered about the correct word. In my woodworking shop, I have a similar tool, except it has small teeth arranged in a random pattern instead of the spiral cutting edge. I always called them a burr and the ones with the spiral cutters a mill. Not being a machinist, I'm not sure about the correct terminology. Thanks for the comment!
@@xraytonyb Without trying to be pedantic and in the way of joining in with the conversation, I've always understood a ball mill to be a rotating drum with steel or ceramic balls inside it. I used one in the early 70s to mill pigments for determination of colour strength and as a way of making sure blended pigments were perfectly mixed.
@@xraytonyb I am sure there is bound to be crossover in naming terms from one sector to the next. I work in a tool and die shop as a CNC programmer and the term burr is a wide range of bits that you would put in a die grinder (similar to a dremel) for hand shaping, often carbide but also high speed steel. For a machinist a ball mill is visually similar to an end mill but it has a (hard to imagine) ball shaped end heh. Just google end mill and ball mill. Keep in mind "ball mill" is a short term for "ball end mill," in my line of work anyway, we always use the term ball mill and skip saying "end." The actual "ball mill" is exactly as it sounds (partially described by jonka1) a mill that crushes shit up using balls.
@@xraytonyb...as I understand it, an "end mill" removes material in chips, using a shaving action, while a "burr" removes material in fine particles- like a file does.
Judging by all the comments, I am thinking that one misspoke word has gained more popularity than the whole rest of the video! I will be sure to make a correction on the next video. Thanks for catching that!
You mention "Q" as a measure of selectivity. I think it's helpful to remember what "Q" stands for: "Quality". Of course this is "quality" defined as the amount of selectivity a given coil/ circuit possesses. But to me, it's helpful to remember that this was the initial definition of "quality": how narrow the bandwidth of a given coil/ circuit was.
@@xraytonyb you probably did; I guess this may all be a bit redundant for many here, but as an audio engineer I'd always wondered: "Why is 'Q' *higher* when the bandwidth is *lower* in an equalizer? Doesn't make any sense!" Well, of course after I learned that the term came from the early days of radio and that the quality of a coil/ circuit would be deemed higher if its frequency response was *narrower* (i.e. had greater selectivity), it all made sense. I also see you've been at this long enough that you've poked around a Miller catalog or two, or twenty; finding a Miller catalog online was an amazing revelation to me. Saying that these coils don't readily cough up their inner mysteries would be a massive understatement. I wish I'd had videos like yours- or that I had known somebody like you- twenty years ago, when I first stared blankly at an IF coil and only vaguely understood their true nature. Learned a lot here: for one, I hadn't considered the possibility that the IF can itself affects the capacitance! Thanks a million, once again.
90-100 pf is usually good to the 455kc AM if transformers, the Sams part list is showing you the replacement part numbers for those particular Merit, K-tran, ect. brands the manufacturer of the equipment probably used whatever brand they got the best deal on, usually a very many radio manufacturers used these rotten Automatic Radio brand transformers witch tells me they must have been the cheapest available back then, it seems that Automatic must have been the only company that used that cup shaped ferrite, most others used the phenolic tube with the slugs inside.
you should be using double film chip capacitors they have the lowest inductance they look like tantalum capacitors what you've got what is not bad but not as good as chip capacitors
I sometimes wonder if we couldn't just use one of those small, color-coded transformers out of an old piece of electronics, test it, build a stand-off out of metals pins and perf-board, solder it up to the pins, and slap that puppy in there. I'm pretty sure it would work, but it wouldn't look all that pretty, unless we hid it inside of the old metal case.
If you mean the types used in transistor radios I wouldn't try it the coils are not insulated well enough I suspect they would short PRI to SEC in a short time.
@@olradguy I thought about this, and then I looked at the size of the wire we're dealing with, and all of those wires looked pretty damn thin, telling me that we're dealing with low levels of current. Admittedly, this probably wouldn't work in all situations, but I'm starting to think that it might work in most situations. I guess I can try it and see what happens.
@@davehebert3403 i am more concerned with the transformer arcing over pri-sec these were never designed to operate at voltage levels that tube equipment run at ,those small transformers are insulated only by the varnish on the wire and are wound one winding on top of the other.
@@olradguy I get where you're coming from, no problem, but my mind keeps telling me "high voltage; low current; thin wire." A fly-back coil comes to mind, for instance, as well as a tesla coil, and they deal with very high voltages. Since silver-mica disease is something that's not going to be leaving us anytime soon, why shouldn't we think out of the box and experiment with things that could possibly simplify the way we deal with certain situations.
(@12:17) - You say, “Adjust the slug all the way into the coil...” This is obvious if you’re adjusting the top-most coil (the one furthest away from the base where the wires come out), but what about when you’re adjusting the bottom coil, especially if the only adjustment access is through the top of the can? 🤔
Either way, you still want the slug to be all the way into the coil. If you aren't sure about CW vs CCW, you can shine a small flashlight into the coil and see where the slug is. Just remember, moving the slug towards the middle of the coil form is driving the slug into the coil, regardless of weather its the top coil or bottom coil. Did you see the coil in the video? If you look closely, you will see that both slugs are fully engaged with the coil when they are driven in towards the middle of the form. Driving them out away from the center and towards the outside of the coil form disengages them. The other types of coils with the phenolic tube is the same, except the slug is actually inside the coil form instead of around the outside. The principle is still the same. Hope that helps.
Has anyone copied the FISHER 500 chassis using 1V heater Vacuum tubes and a B+ of 45-60V so it can be run of a PSU giving 1V for the heater and 20-60V or so it can be 1D Cell and and 4x12V car batteries for use down on the beach.
You are right, it is best known as Intermediate frequency. But how is it produced? By intermodulation of the Antenna signal with a local oscillator that gets mixed down to the intermediate frequency. It then this intermediate frequency gets filtered all neighbour channels and other unwanted frequencies get filtered out. Intermediate frequence or Intermodulation frequency - just 2 names for the same thing.
What about going with Collins Mechanical Filter modules designed for 455Khz and forget about fixing the Intermediate Frequency Transformers, if it were me doing the repair I would try to rebuild the whole chassis using Collins Mechanical Filter Modules for 455Khz and going with TELEFUNKEN Space Charge Vacuum Tubes so as to make the chassis to work on at a future date, as for the 10.7Mhz cans I would also use Collins Mechanical Filter modules to replace the 10.7Mhz cans and adjustments are then no longer needed.
Why the h... did the manufacturers/designers in those days use such sh... mica capacitors? What are the advantages? They are more complicted to install and more expensive than simple ceramic caps. The possible higher Q can´t be the reason because the resulting Q is determined by the parallel circuit in the IF-section independent from the Q of the capacitor. Any idea?
My understanding is that those built-in mica caps were fantastic back in the day for a variety of reasons. Manufacturers were likely considering this: mica sheets were extremely easy to build into a coil assembly, quickly, on an assembly line, likely in an automated or semi-automated process. Not only that, but the capacitance would be pretty spot-on (plus or minue a few pF). This reduced a coil manufacturer's assembly time substantially compared to having a person solder in a separate couple of capacitors on *every single coil*. You can imagine how much money this would save a manufacturer of coils on a production scale, and again: the cost of production was then brought down while still maintaining precision, or possibly even increasing it. It also was useful for achieving further miniaturization. At the time, no one was sitting around wondering whether, in the year 2020, sixty-two years hence, mica capacitors might break down under adverse storage conditions. These radios were designed and built for 10-20 years' service life, and no more. °Maybe° a nice receiver like this would've been designed with a service life of 25-30 years, tops. Even if any of the designers had stopped to consider whether the mica caps in a radio coil assembly might go bad for whatever reason (at the time, it was far from clear to anyone at all that there would be such a thing as "silver mica disease" in the distant future), they likely would've thought "Well, you can just go down to your local electronics store and get a replacement coil. After all, there are at least two or three radio/ tv repair shops in every town; why wouldn't anyone just do that and throw out the old coil?" Just for context: the surprising rapidity and suddenness of the vast, fundamental changes in electronics resulting from the massive advances in transistor reliability and mass-production over the ten years following these radios' production (~1957-'59) were mostly unforeseen. People knew something was coming, but no one could quite predict when, and even if, transistors were going to but by the late '50s transistors were still in their sorta-unreliable stage. Tubes were still king. If you were sitting in 1957, when this was manufactured, you'd likely have agreed that tubes were going to be a major part of mainstream consumer electronics for a good while- at least for the foreseeable future- because they still haven't gotten this transistor thing sorted out yet. Then everything changed, just in the next seven years. And even then (by 1964-66), germanium transistors were still the norm in the power stages of the new solid-state receivers, because they just hadn't gotten the silicon power transistors reliable enough. Then, over the next five years, until about 1970, that all changed, and silicon transistors were suddenly reliable and reproducible enough that they could begin using them on mass-production scale in high-fidelity receivers. Technology was changing fast. Really fast. What I'm rambling on about is this: almost no one could've imagined a world where technology was so cheap you would rather throw a whole set away instead of just heading to your local radio shop and grabbing one of these coils off the shelf. That's the way it had been for as long as anyone could remember. That's the way it was always going to be. Why would you throw away a radio which could be repaired? Parts and labor will always be relatively cheap, won't they? That question probably wasn't even considered, as it was nearly unimaginable. And of course, there were many folks who were into this new "DIY Hi-Fi" fad, and therefore many, many more people just floating about who could repair a radio- or at least replace a coil. Consider this: in 1974, the first personal computer ever offered for sale was offered as a *kit*. A kit. And the company *sold out* of them, many times over, in pre-orders, in just a month or two. That's how popular electronics was as a hobby, even as late as 1974. Throw away a replaceable part, like a tuning coil, and replace it yourself with the one from Radio Shack or Allied or Miller? Sure. Throw away a nice high-fidelity receiver which can be repaired? Unthinkable for just about anyone. Even "cheap" radios were relatively much more expensive back then. A radio/ receiver like this one would've cost $250.00; that's over $2,300.00 in today's money (see the Fisher 500 ad on page 11 at worldradiohistory.com/Archive-All-Audio/Archive-High-Fidelity/50s/High-Fidelity-1957-Jul.pdf).
Skipping over a clear explanation of the SG and Scope connections was not very helpful. Otherwise a good description of IF xformers and sweep analysis.
Too bad these are referred to as transformers, since transformers don't typically have capacitors. Confusing for ignorami like me. Thanks for the expl.
I think the reasoning is because the signal is magnetically coupled between the primary and secondary. Power transformers also have a Quality Factor, but it isn't important, as it is running at a fixed frequency (50 or 60 Hz). Try running the transformer at higher frequencies and watch what happens! Thanks for the comment!
ok if everyone did this you wouldnt have any left and since they dont make them anymore when theyre gone theyre gone. Its a piece of history. You can get an am transmitter and broadcast your own content to these.
Hello Tony!! It's impressive to see so much dedication to how these things were done in the past. And even more impressive is to see your work. Congratulations!!!
This was such a pleasure to watch. With all of the negative things in the world right now, and the negative uses that the Internet can be put to, seeing someone with a passion for their subject take the time to pass on their knowledge in such a calm and honest way is truly inspiring. Thank you Tony, these videos are sincerely appreciated and the effort that goes in to making them is not taken for granted.
Amen.
This is the best tutorial on dealing with SMD that I have run across. Thank you Tony!
Besides being an excellent electical engineer (or whatever you are, x-ray) you are an outstanding pedagogue. Your employees are fortunate to have an employer skilled in both fields.
Your vids are so amazing
Educational content is so rare these days.
So agree with your comment about "show them how but don't give the answer."
Give a starving person grain and by next week they are starving again.
Give a person a spade, land, grain & education on how to farm will never go hungry.
Thank you for making these vids.
...I'd say fishing is a lot simpler-(?)
Tony, everytime when i see you on your new video i almost have tears in my eyes and i feel like I have met someone close after years of separation. Thank you for everything and God bless you.
Thank you for the kind words!
@@xraytonyb Also know that You taught me everything and today your hobby is also my hobby.
Working on a "The Fisher" 500-C receiver from 1963 with the optional MPX adaptor for FM stereo. This unit has the best consumer equipment assembly quality and solder joints I have seen outside of military and medical equipment. I worked for Physio Control building medical equipment, and for the Navy building torpedo fire control systems and torpedoes. Love the refresher course back to the days of my electronics training, inspired me to get out my old training manuals and brush up on math and theory I had forgotten about. Remember ELI the ICE man? Left hand rule?
I actually talked about old ELI in a couple of my other videos. Thanks for the comment!
...ELI the ICE man, lives in SARL PARC...
Thanks, Tony! I rebuild IF cans pretty often but I learned a lot from you. I especially like the pencil graphite on the slugs!!!
Wow I'm impressed once again. your a genius tony I learned so much from your videos. Thanks
I agree, you should put in NP0 (that is "n-p-zero" for the people to order) caps to minimize drift due to thermal effects. Putting in an I.F. can with the adjustable ferrite cores in the mid position, then determining the CORRECT FREQUENCY of the I.F. chain (for example, cans from the early days when people tried to avoid paying RCA for their 455 KHz design which was patented) you could end up with the correct capacitance by using a formula. By the way, most schematics don't show different coils inductance. You would have to VISUALLY mark the direction of the can in the circuit. If the leads are color-coded, all the better. Replace them any time if you can! Good luck! Get rid of any bizarre caps such as disc ceramics in the oscillator circuit to make it stable by using silver micas.
This is really an outstanding piece of work. Congrats to both of us, as I learned much just watching this - as will many for years to come.
5:28 It'd be a wider sweep than that, as AM signals get up to 5kHz. As such, the sweep range is probably more like 440kHz to 470kHz, to give a good 15kHz either side of the IF frequency.
50+ years ago (in my pre teens), I thought this stuff just may be my calling. However, a capable knowledge base, and outlook for this as a career was unfortunately lacking. Although I did go to technical schools, etc, and (usually) successfully did some of this work, I chose to go with oil & gas, then telecom (phone company), as a good living. Fast forward 50+ years, now retired, have struck gold (or oil gusher), with your channel .. much thanks Tony ...
Thanks Tony. That helped put the whole diseased transformer repair idea together for me.
Good video Tony. Besides you can tune a radio, but you can't tune a fish. Keep the videos coming Tony. Love your videos.
Nice video once again Tony thank you,I like when you give out the little tech tips in most of your videos, for instance when you mentioned the starting points value for those IF capacitors
SUPPER! Great trouble shooting procedures presented. Now I can fish, thanks.
Thanks to vintage pieces, the repair business lives .. as with appliance/outdoor power equipment ,etc., the margin of what the customer is willing to pay to repair vs buying new is quite slim. This leaves the one man show/hobbyist, a good chance of acquiring vintage/rare pieces for little/close to nothing/or even free, and coming up with some very cool, desirable stuff ...
Very nice Fisher 500 Tony!!! Thanks for the expl.
Thanks Tony, enjoyed the video. First tube tuner I worked on was a Zenith add on for a consolette, it sounded like it was in the middle of a thunderstorm on am and fm from one end to the other. Replaced all the silver mica caps, works great now.
I believe that the stages in any I.F. Have different Q on each stage to prevent self resonance through the radio, which would be why very similar coils have different part numbers. Also sometimes the peaks are slightly offset from each other for the same reason, and to slightly broaden the bandwidth.
...as I understand it, the SIGNAL POLARITY of the individual IF stages are selected to prevent oscillation in the IF amplifier-(?)
Great instructional video. You’re correct in saying that we are all going to see this problem at some time.
:) That unit Shang0 did the variable caps on was my Silvertone. our channels the best Tony. Thank you so much!
Very clear tutorial and explanations Tony
I like those style IF transformers over tthe cardboard tube. these can't get stuck, but you do have to be gentle since plastic is involved.
...THAT'S THE TRUTH-(!)
Sorry Tony for overdoing it with commenting .. but, back during the 60s .. we had this White plastic case GE tube radio, bought brand new circa 1962 .. (BTW the brown/maroon radio in the foil capacitor video is a near dead ringer) mom placed it on top of the refrigerator, and played it all day every day until (supper time), for approx 10 years until about ‘72 .. all it would do is “crackle”. I was in a TV repair shop course when a Sr in HS. I asked my instructor about it, and he said “the IFs” (I had already tried testing/swapping tubes at the local drug store). Anyhow, prior to, I tried to keep it around, but somehow mom found it and threw it out before I could bring it in. Amazing how I recall this like yesterday, 50 years later ...
...NOTHING is FOREVER: not in THIS world-(!)
Nice video
Good explanation.
Very good.
that equation was what i learned in AC circuits, as well as reactance equations for inductors and capacitance
What a great and timely video Tony! I'm currently working on a 1946 Zenith AM/FM console with one or more bad IF transformers and was wondering how to go about fixing it. You've answered all of my questions. One stop learning. 🙂
...did you fix it?
Great video. I have the same rf generator. Those old hp generators are great I have the sister function generator also. I have been using these for a very long time no problems
An excellent video, Thank You!
Thank you for sharing Tony take care
When calculating or empirically chosing caps to suit an IF transformer out of circuit it is worth leaving a few pF out to account for the stray capacity of the circuit the transformer will be soldered back into. More likely to be of benefit with the 10.7 mHz ones. This might explain why with one you reduced one cap from 30s to 20s pF
...THAT'S THE TRUTH-!!!
Good idea using the graphite Tony, I've used it on locks as well, as grease can be too sticky
...ABSOLUTELY-(!)
My late dad told me it's not just to learn but learn how to learn. IF means intermediate frequency not intermodulation. It's an in-between you could say like a gear. Great job.
Agreed, it should be "intermediate" at 13:19.
@@russellhltn1396...I THOUGHT SO TOO-(!)
Thanks Tony for the great video. I have dealt with some of these Miller type transformers as well. I appreciate the information on calculating the capacitor value because I have been using the Shang066 method. This method is much more precise. I do have one tip for you however lol. Instead of using the dremel with a burr to remove the rivet, use a sharp drill bit just smaller than the diameter of the rivet. Either in a pin vise or on low speed with a drill. Much more control over popping that outer portion of the rivet. Thanks again!
I have had some bad experiences with the drill bit method. Some folks are really good at it, but I'm not one of them! I like the control I have with the Dremel. Perhaps when I'm done with my therapy sessions from the past experience, I'll give the bit-method another try ;)=)
@@xraytonyb ...yes, drill bit tend to GRAB-(!)
Tony, You hit a KEY NOTE in your video about diagnosing a problem and using ANALYSIS! to figure out a solution. Well that is something you learn in school. School just enables that ability for someone to realize and utilize and hone in on those skills. For some people it takes longer to do cause they don't have the skills, or most importantly experience and skills, cause those two ingredients is what provides possible solutions. This is true in most of the engineering and sciences. There are some people that just dont have the skills to do analysis and diagnostics.
Excellent teacher, well done. This is definitely one for my collection.
IF stands for Intermediate Frequency . I think Tony Got Silver Mica disease from those cans lol. Great explanation of how to solve LC tuning
I noticed I said that after I processed the video. I didn't feel like reprocessing it, so that's how it got uploaded. If that's the only mistake I made. then I'm thrilled. I got silver mica disease from looking at this stuff for so long! ;)
@@xraytonyb LOL... You caught Intermodulation Distortion Disease eh Tony? I heard that RF "distancing" will cure that problem... Or you can just isolate yourself inside a Faraday cage and recover that way!
Thanks for the great video and detailed explanations Tony.
Pen lubrication was smart :-)
...that's a PENCIL- I never heard of a PEN that used graphite...
Thank you for the pencil trick!!
...if anyone is interested, I'd suggest using silicone lubricant instead of graphite because: 1- graphite is an ELECTRICALLY CONDUCTIVE substance, and 2- silicone lubricant is good for dry, brittle plastic-(!)
I usually have an eagle-eye for typos so I’m surprised I just noticed the one in your introductory warning. The “their” in “at their own risk” is spelled thier. Also, IF generally stands for Intermediate Frequency, I haven’t heard it called Intermodulation Frequency as you stated in the video. Sorry for the nitpicking, absolutely love your channel!
Shango066 is very good at bringing radios and tv's back to life, he gives the impression that he is not an expert.
He is an expert in his own field, clever and a sharp mind :-D
I love his sarcastic comments, so dry, he takes no prisoners lol.
Like yourself, he is very enjoyable to learn from :-D
...ABSOLUTELY-(!)
YES! 3:13! Every friggin' day, I have this conversation at work. Usually with the same guy.... I have to follow this guy all the time and fix what he didn't.... ARRGGGGG. Sorry. Sorry, I am sure we have all been there and someone probably felt that way about me at one time, but..... ugh. I feel much better now. Thank you.
if i understand those transformers corectly very similar devices are used in old rc toys only instead of magnetic transfer between the coils the signal from first tank circuit is feed into transmiter transistor and then reciever transistor is tuned with another half of the coil and a slug
when i was very unexperienced with electronics i was kind of a hack guy and when i got 2 of the same analog rc cars i decided to tune one to a different frequency by randomly swaping coils , slugs and capacitors, and it kind of worked
i wish i seen this video 15 years ago :]
Tony, your videos are simply amazing! I wish that you would do a short session on exactly how to hook up the WR-50B sweep function across the IF can to the oscilloscope to get the tracing as shown. It appears that you did this without a ‘ramp’ signal on X axis, and NOT in XY mode? I have been trying to work out any possible such
setup for a couple years, and not been satisfied. Videos (and forum threads) just seem to skip to ‘Wa-La!’, there it is! Please consider this! Thanks!
...I'd imagine that the signal generator is connected across one coil, and the oscilloscope is connected across the other coil...
my thoughts but shouldn't you adjust the cores to the center of travel before you measure the inductance of the coil and calculate the capacitor value?? wouldn't this help prevent you from reaching the top or bottom before peaking?
The Fisher front ends are very good but I like the older tube H.H Scott front ends.
...well, "ya CAN'T please EVERYBODY!!!"
A Quick way to disassemble these transformers is to use a pair of 4.5inch FLUSH cutters cut the top of the eyelet off then you can pry off the metal clamp and plastic part and mica,no drilling or dremel needed, also i am thinking about using smd npo cap or one of those really small axial lead round monolythic types just cut the internal lugs short & solder in the cap and secure in place with some glue, just although i haven't tried this yet.
For me, the dremel seems to give me the best control. I've had the brittle plastic crack a few times when either the drill bit caught or I got a bit too rough with the cutters. It's important to find the method that works best for you. I appreciate you sharing your techniques, as they may be really helpful to others. Thanks for the comment!
...in order to do THAT successfully, you'd need: 1- a sharp pair of "flush cutting" diagonal cutters, 2- a lot of skill, and, 3- more than a little LUCK...
Tony did i just hear you say "intermodulation frequency"? @13:17. I kind of think you might be messing with us a bit? LOL
Great job Tony. If you use electrical/physics math formulas, it's much easier dealing with the units in scientific notation. All the zeros can become a overlooked failure point. I can't imagine having a calculator that doesn't use the format.
I liked converting to exponential notations then using logarithms to solve long division problems.
I should have done a better job when I wrote out the formula. I didn't properly write down the exponent for the frequency and I wrote the decimal instead of scientific notation for the inductance. I'm starting to realize that some viewers really pay attention to everything and if they are just learning, something like that could throw them off. I'm thankful that some of the more experienced folks like yourself are keeping track of these things! I really appreciate it!
@@xraytonyb Not a criticism at all. Just a suggestion. Any new tech's should consider taking the time to learn it. It's really easy and will save you lots of headaches from the old way of using a really long abacus :). We have it so easy now with hand held math machines!
I think that when you measured the capacitance of the first cap your hand was in close proximity to the coil introducing more capacitance. On the second cap that you measured you put the coil down on the bench and completely moved your hand away for a value of 105 pf as opposed to 135 pf value. When measuring very small capacitance values like this even minor variations can make a big difference. Check at 21:38. Stay well. ATB Doug.
You are correct. I did, however, measure these values several times off camera as well. This meter really doesn't seem to be affected a whole lot by capacitive coupling by your hand, unless you are actually touching the leads. This little meter is amazing. It even self-calibrates each time you power it up or hold the reset button. Even my more expensive meters aren't as good with very low capacitance as this one is.
...NOBODY'S INFALLIBLE!!!
Great video - Master teaches grasshopper lol
Very good and useful job!
I did one of these receivers a few years ago, some supposed Fisher "expert" was in it before it came to me, a great number of the IF's needed repaired, most of the work was broken/cracked slugs (screwdrivered) I had to find enough of the Automatic Radio slugs from junked transformers I needed 8-10 of them, after I repaired the IF section the FM still wasn't just right turned out someone got into the discriminator coil, inside were two 1.5 meg resistors, the only problem someone put a 1.5k resistor in for one of the 1.5megs. "Expert" yeah right, the owner told me he paid around $500.00 for this "expert" work.
I remember when my cousin had his TV shop, he was able to purchase replacement slugs at the parts store. I wish you could still buy them like that!
...there are bunglers in EVERY profession-(!)
Do you have a sinad meter? Would be a better way of checking the actual sensitivity in a quantitative way, 12dB SINAD is the standard level used as that is considered the minimum for intelligible speech.
Maybe what your experiments show is that it's better to find the correct cap value with the coils back in circuit using a tiny variable. Could save hours of time too.
I've used that method in the past as well, but this was meant more as a demonstration for those who have never seen how these transformers work. Thanks for the comment!
Tony, where would be a good place to source a sweep generator (already have a 2 ch PicoScope) .. I have a vintage Westinghouse H778N7 (in a very cool maple mini maple console HiFi like cabinet), with a SAMS .. looks very similar to your Fisher, that I’m looking at to fix .. PS, it did the classic “worked at first” .. I’m assuming it has the same “itis” and “osis” as the Fisher ...
Honestly I would expect the sweep to be something like 440kHz to 470kHz - you don't want the transformer to be super peaky (ie. a high Q), otherwise you'll lose the higher frequencies of the modulating signal.
I was just picking an arbitrary set of numbers as an example. In most sweep generators, you can adjust the sweep width to whatever you want. On this unit, it is fixed, but I never measured to see what the sweep width was. Sorry for the confusion!
IF stands for intermediate frequency, not intermodulation frequency.
I wonder if you could answer my question in my quest for information about i.f. transformers.
I have a 1944 Wireless 19 Set I'm trying to improve reception on as there's not a lot of gain. It works better now after a few adjustments as I heard very little when I first got it. I looked at the i.f. transformers because the cores were jammed solid and could not be adjusted. I think they were adjusted and glued when manufactured which makes sense as they wouldn't want the cores to go off tune when a tank travels over rough ground. I only looked inside the 2nd i.f. and found one capacitor of 140pF and one of 47pF. There was an impression in the wax where I assumed a 140pF had been removed.
I wondered why and looked in my radio books, some very technical with complex calculations and some more basic but couldn't find anything. After months of searching the internet I found one reference about changing one capacitor to increase selectivity but it didn't give values. Does it make a higher Q? But wouldn't changing one capacitor throw it off tune as you have demonstrated? An Australian circuit for a 19 Set shows 140pF in both i.f.t.'s.
I read yesterday in an old magazine article online the first i.f. is over coupled. It again makes sense to detune things make a deaf receiver because they wouldn't want to listen to Germany when they want to communicate 20 miles.
Have you any idea on this? Was the reference to changing one capacitor correct? I never did find anything more about it.
I can see a lot of work needed, maybe S-M capacitor disease and resistors gone high, the audio c.w. (Morse Code) filter is extremely bad and not doing much so I'm looking to replace the R's and C's in that, and somehow free the i.f. cores. However, as bad as it is I've had a number of contacts, the furthest being Scotland at about 250 miles but it was hard work on my part to receive him.
Bill, G4GHB.
I just found out about you. I've got 4 scope made by hp do you repair them?
the RCA rf generator is in the sweep mode chanel 1 of the scope is in AC coupling it mesure the amplitude , but how the scope horizontal is set up ? because the ref generator does not have sweep output to drive the horizontal of the scope
...the RF sweep frequency is the 60 cycle line frequency- and an awful lot of oscilloscopes have a "LINE FREQUENCY" setting on the horizontal sweep input(s)...
12:00 You should indicate whiich side in the video is the secondary (opposite to the schematic). I had to go by the red scope clip.
At 37:13 shouldn't you be using the frequency in Hz not in MHz? Just as C and L are in Farads and Henrys?
So like 10700000 and not 10.7?
If some of the capacitors in those cans are defective, isn't it safe to assume that the others if not yet defective they will eventually go bad.
So their going to need to be replaced sooner or later anyway, so just take all when you are at it?
Yes, the 10.7^2 should be 10.7MHz^2, but the result is in pf, which is 10^-12 and therefore the "mistake" is compensated - luckily!
Would you just see the sine wave if the signal generator was not sweeping and just set to 455khz?
Yes. The amplitude would depend on how close the frequency of the signal is to the resonant frequency of the transformer.
33pf is typical for the 10.7 if transformers, also Shangos way to find the right cap. value works good EXCEPT you have to be sure the set was never "screwdrivered".
Is that a Miller I3-PC3 IF Transformer?
Yep I'm gonna be that guy. If you care about what that bit is called. It's called a burr not a ball mill. If you don't care what its name is, well call it whatever you want bud. Great video as always, enjoyed watching and learning.
I've always wondered about the correct word. In my woodworking shop, I have a similar tool, except it has small teeth arranged in a random pattern instead of the spiral cutting edge. I always called them a burr and the ones with the spiral cutters a mill. Not being a machinist, I'm not sure about the correct terminology. Thanks for the comment!
@@xraytonyb Without trying to be pedantic and in the way of joining in with the conversation, I've always understood a ball mill to be a rotating drum with steel or ceramic balls inside it. I used one in the early 70s to mill pigments for determination of colour strength and as a way of making sure blended pigments were perfectly mixed.
@@xraytonyb I am sure there is bound to be crossover in naming terms from one sector to the next. I work in a tool and die shop as a CNC programmer and the term burr is a wide range of bits that you would put in a die grinder (similar to a dremel) for hand shaping, often carbide but also high speed steel. For a machinist a ball mill is visually similar to an end mill but it has a (hard to imagine) ball shaped end heh. Just google end mill and ball mill. Keep in mind "ball mill" is a short term for "ball end mill," in my line of work anyway, we always use the term ball mill and skip saying "end." The actual "ball mill" is exactly as it sounds (partially described by jonka1) a mill that crushes shit up using balls.
@@xraytonyb...as I understand it, an "end mill" removes material in chips, using a shaving action, while a "burr" removes material in fine particles- like a file does.
What happens in old radio with 465 if stages.
The peak would be at 465kHz instead of 455. Other than that, everything else would be the same.
What are the oscilloscope settings...I figure it’s DC volts right ?
...no, it's AC.
Probably better to use an FET scope probe when peaking the transformer. Otherwise you’re adding 10-15 pF.
Allison Cawthon excellent!
@13:20 should that not be "intermediate frrequency"?
Judging by all the comments, I am thinking that one misspoke word has gained more popularity than the whole rest of the video! I will be sure to make a correction on the next video. Thanks for catching that!
52:05...what about silicon lubricant?
For some REASON I can't get the same pattern that you get. WHY?
You mention "Q" as a measure of selectivity. I think it's helpful to remember what "Q" stands for: "Quality".
Of course this is "quality" defined as the amount of selectivity a given coil/ circuit possesses. But to me, it's helpful to remember that this was the initial definition of "quality": how narrow the bandwidth of a given coil/ circuit was.
I would have to go through the video, but I think I mentioned this somewhere. If not, I'm glad you reminded us!
@@xraytonyb you probably did; I guess this may all be a bit redundant for many here, but as an audio engineer I'd always wondered: "Why is 'Q' *higher* when the bandwidth is *lower* in an equalizer? Doesn't make any sense!"
Well, of course after I learned that the term came from the early days of radio and that the quality of a coil/ circuit would be deemed higher if its frequency response was *narrower* (i.e. had greater selectivity), it all made sense.
I also see you've been at this long enough that you've poked around a Miller catalog or two, or twenty; finding a Miller catalog online was an amazing revelation to me. Saying that these coils don't readily cough up their inner mysteries would be a massive understatement.
I wish I'd had videos like yours- or that I had known somebody like you- twenty years ago, when I first stared blankly at an IF coil and only vaguely understood their true nature.
Learned a lot here: for one, I hadn't considered the possibility that the IF can itself affects the capacitance!
Thanks a million, once again.
...well, "ya CAN'T please EVERYBODY"!!!
90-100 pf is usually good to the 455kc AM if transformers, the Sams part list is showing you the replacement part numbers for those particular Merit, K-tran, ect. brands the manufacturer of the equipment probably used whatever brand they got the best deal on, usually a very many radio manufacturers used these rotten Automatic Radio brand transformers witch tells me they must have been the cheapest available back then, it seems that Automatic must have been the only company that used that cup shaped ferrite, most others used the phenolic tube with the slugs inside.
The 2nd IF transformer is about half the DC resistance of the 1st one. Showing that they are NOT the same transformers.
It also has a different part number in the parts list. Thanks for the comment!
...who said that they WERE all the same-(?)
you should be using double film chip capacitors they have the lowest inductance they look like tantalum capacitors what you've got what is not bad but not as good as chip capacitors
I sometimes wonder if we couldn't just use one of those small, color-coded transformers out of an old piece of electronics, test it, build a stand-off out of metals pins and perf-board, solder it up to the pins, and slap that puppy in there. I'm pretty sure it would work, but it wouldn't look all that pretty, unless we hid it inside of the old metal case.
If you mean the types used in transistor radios I wouldn't try it the coils are not insulated well enough I suspect they would short PRI to SEC in a short time.
@@olradguy I thought about this, and then I looked at the size of the wire we're dealing with, and all of those wires looked pretty damn thin, telling me that we're dealing with low levels of current. Admittedly, this probably wouldn't work in all situations, but I'm starting to think that it might work in most situations. I guess I can try it and see what happens.
Maybe we can talk Tony into giving it a try on camera. That would make for an interesting video, for sure.
@@davehebert3403 i am more concerned with the transformer arcing over pri-sec these were never designed to operate at voltage levels that tube equipment run at ,those small transformers are insulated only by the varnish on the wire and are wound one winding on top of the other.
@@olradguy I get where you're coming from, no problem, but my mind keeps telling me "high voltage; low current; thin wire." A fly-back coil comes to mind, for instance, as well as a tesla coil, and they deal with very high voltages.
Since silver-mica disease is something that's not going to be leaving us anytime soon, why shouldn't we think out of the box and experiment with things that could possibly simplify the way we deal with certain situations.
(@12:17) - You say, “Adjust the slug all the way into the coil...” This is obvious if you’re adjusting the top-most coil (the one furthest away from the base where the wires come out), but what about when you’re adjusting the bottom coil, especially if the only adjustment access is through the top of the can? 🤔
Either way, you still want the slug to be all the way into the coil. If you aren't sure about CW vs CCW, you can shine a small flashlight into the coil and see where the slug is. Just remember, moving the slug towards the middle of the coil form is driving the slug into the coil, regardless of weather its the top coil or bottom coil. Did you see the coil in the video? If you look closely, you will see that both slugs are fully engaged with the coil when they are driven in towards the middle of the form. Driving them out away from the center and towards the outside of the coil form disengages them. The other types of coils with the phenolic tube is the same, except the slug is actually inside the coil form instead of around the outside. The principle is still the same. Hope that helps.
51:46...isn't graphite conductive-(?)
Has anyone copied the FISHER 500 chassis using 1V heater Vacuum tubes and a B+ of 45-60V so it can be run of a PSU giving 1V for the heater and 20-60V or so it can be 1D Cell and and 4x12V car batteries for use down on the beach.
..."4 12v car batteries" sounds awful HEAVY-(!)
53:14...I'm surprised-(!)
I would use my Vector Network Analyzer - Bode 100 from Omicron Lab ( www.omicron-lab.com/)
to characterize the coil , I recommend very warmly
Intermediate frequency
You are right, it is best known as Intermediate frequency. But how is it produced? By intermodulation of the Antenna signal with a local oscillator that gets mixed down to the intermediate frequency. It then this intermediate frequency gets filtered all neighbour channels and other unwanted frequencies get filtered out. Intermediate frequence or Intermodulation frequency - just 2 names for the same thing.
What about going with Collins Mechanical Filter modules designed for 455Khz and forget about fixing the Intermediate Frequency Transformers, if it were me doing the repair I would try to rebuild the whole chassis using Collins Mechanical Filter Modules for 455Khz and going with TELEFUNKEN Space Charge Vacuum Tubes so as to make the chassis to work on at a future date, as for the 10.7Mhz cans I would also use Collins Mechanical Filter modules to replace the 10.7Mhz cans and adjustments are then no longer needed.
Wouldn't impedance mismatch occur?
@@johnnytacokleinschmidt515 If it is done right everything should be alright.
@@DAVIDGREGORYKERR...HECK, THAT'S TRUE FOR EVERY ENDEAVOR-(!)
Because, as he said, it's the bandwidth. The Fisher is about fidelity. The Collins is about selectivity. You need more bandwidth for fidelity.
Wonder how many people clicked off this video when they heard math.
Math; still the strongest type of content filtering ;)
Why the h... did the manufacturers/designers in those days use such sh... mica capacitors? What are the advantages? They are more complicted to install and more expensive than simple ceramic caps. The possible higher Q can´t be the reason because the resulting Q is determined by the parallel circuit in the IF-section independent from the Q of the capacitor. Any idea?
My understanding is that those built-in mica caps were fantastic back in the day for a variety of reasons. Manufacturers were likely considering this: mica sheets were extremely easy to build into a coil assembly, quickly, on an assembly line, likely in an automated or semi-automated process. Not only that, but the capacitance would be pretty spot-on (plus or minue a few pF). This reduced a coil manufacturer's assembly time substantially compared to having a person solder in a separate couple of capacitors on *every single coil*. You can imagine how much money this would save a manufacturer of coils on a production scale, and again: the cost of production was then brought down while still maintaining precision, or possibly even increasing it. It also was useful for achieving further miniaturization.
At the time, no one was sitting around wondering whether, in the year 2020, sixty-two years hence, mica capacitors might break down under adverse storage conditions. These radios were designed and built for 10-20 years' service life, and no more. °Maybe° a nice receiver like this would've been designed with a service life of 25-30 years, tops. Even if any of the designers had stopped to consider whether the mica caps in a radio coil assembly might go bad for whatever reason (at the time, it was far from clear to anyone at all that there would be such a thing as "silver mica disease" in the distant future), they likely would've thought "Well, you can just go down to your local electronics store and get a replacement coil. After all, there are at least two or three radio/ tv repair shops in every town; why wouldn't anyone just do that and throw out the old coil?"
Just for context: the surprising rapidity and suddenness of the vast, fundamental changes in electronics resulting from the massive advances in transistor reliability and mass-production over the ten years following these radios' production (~1957-'59) were mostly unforeseen. People knew something was coming, but no one could quite predict when, and even if, transistors were going to but by the late '50s transistors were still in their sorta-unreliable stage. Tubes were still king.
If you were sitting in 1957, when this was manufactured, you'd likely have agreed that tubes were going to be a major part of mainstream consumer electronics for a good while- at least for the foreseeable future- because they still haven't gotten this transistor thing sorted out yet. Then everything changed, just in the next seven years. And even then (by 1964-66), germanium transistors were still the norm in the power stages of the new solid-state receivers, because they just hadn't gotten the silicon power transistors reliable enough. Then, over the next five years, until about 1970, that all changed, and silicon transistors were suddenly reliable and reproducible enough that they could begin using them on mass-production scale in high-fidelity receivers.
Technology was changing fast. Really fast.
What I'm rambling on about is this: almost no one could've imagined a world where technology was so cheap you would rather throw a whole set away instead of just heading to your local radio shop and grabbing one of these coils off the shelf. That's the way it had been for as long as anyone could remember. That's the way it was always going to be. Why would you throw away a radio which could be repaired? Parts and labor will always be relatively cheap, won't they? That question probably wasn't even considered, as it was nearly unimaginable. And of course, there were many folks who were into this new "DIY Hi-Fi" fad, and therefore many, many more people just floating about who could repair a radio- or at least replace a coil. Consider this: in 1974, the first personal computer ever offered for sale was offered as a *kit*. A kit. And the company *sold out* of them, many times over, in pre-orders, in just a month or two.
That's how popular electronics was as a hobby, even as late as 1974.
Throw away a replaceable part, like a tuning coil, and replace it yourself with the one from Radio Shack or Allied or Miller? Sure. Throw away a nice high-fidelity receiver which can be repaired? Unthinkable for just about anyone. Even "cheap" radios were relatively much more expensive back then. A radio/ receiver like this one would've cost $250.00; that's over $2,300.00 in today's money (see the Fisher 500 ad on page 11 at worldradiohistory.com/Archive-All-Audio/Archive-High-Fidelity/50s/High-Fidelity-1957-Jul.pdf).
@@RapperBC...YOU SUMMED IT UP PRETTY WELL-(!)
Ceramics drift like crazy on temperature, mica is very stable in that.
You really need a 455Khz crystal marker to determine a frequency peak on the scope.
...YOU BETCHER LIFESAVERS-(!)
Skipping over a clear explanation of the SG and Scope connections was not very helpful. Otherwise a good description of IF xformers and sweep analysis.
@16:14: I think this is a great illustration aid for your explanation of a tank circuit:
ua-cam.com/video/W31CCN_ZF34/v-deo.html
Too bad these are referred to as transformers, since transformers don't typically have capacitors. Confusing for ignorami like me. Thanks for the expl.
I think the reasoning is because the signal is magnetically coupled between the primary and secondary. Power transformers also have a Quality Factor, but it isn't important, as it is running at a fixed frequency (50 or 60 Hz). Try running the transformer at higher frequencies and watch what happens! Thanks for the comment!
This is when you toss the radio out or Part it out on eBay. C’mon its only AM, nothing to listen to worth all this effort and time involved.
...AW, YOU'RE JUST JEALOUS-(!)
ok if everyone did this you wouldnt have any left and since they dont make them anymore when theyre gone theyre gone. Its a piece of history. You can get an am transmitter and broadcast your own content to these.