The problem with your henries is the measurement frequency. The 15 Henries are there, you just don't see them, at frequencies around 100Hz. In order to actually measure the fundamental inductance you have to measure at significantly lower frequency. I deal with very large inductances every day and have a special HIOKI LCR meter that can even measure in the sub-Hz range. I often measure inductors around 15H at 0.5Hz or lower. You can also check the inductance via the step response by measuring the time constant of the coil and then calculating the inductance via the ohmic (DC!) resistance, L=Tau*R...
The choke could have been a filter choke in a power supply circuit that was overloaded and now has shorted turns. Use a .1mfd capacitor in series with the choke and connect your signal generator to the ends. Connect the scope to the center and adjust the generator for maximum signal. It should be near 130 hz.
@@mr1enrollment Shorted turns can be almost any number of turns so the inductance can vary all over the place, from almost no effect to drastic decreases.
It is obvious to the most casual of observers that the 15H min spec is approximately 4 times the measured 2H and that 36,000 ft is twice the 18,000 ft rated altitude and since 4 is 2 squared and given that the Henry leakage function is parabolic the only conclusion one can draw is that this device was flown in the unpressurized hold of a commercial jetliner from the East coast to the West coast at some point in time and the lost Henry's are now floating around the sky inducing dangerous electromotive forces in unwary aircraft.
There are many ways for testing an inductance. You can also connect it to dc power supply and measure how fast the current rises (this method works if your choke has a gap, so it tolerates some amount of dc bias). Ofc, you should treat it as an RL circuit, with R part being dc resistance of the choke... But in my opinion the best piece of advice is given by glasslinger in comments. Try making a tank circuit with your choke and a known, high value cappacitor (small ones are not usable since their cappacitance will be comparable to the selfcapacitance of the choke, so you could not find the resonant frequency), connect the tank circuit to the scope and then hit the circuit with a somewhat high DC pulse. You will get decaying oscillations on your scope. From frequency you can deduce the L of the choke, and from number od oscillations (better to say, the decay constant) you can get some sense of health of the choke. If the choke has any shorted turns the oscillations will decay very very quick. At most , after two or three halfcycles. A good choke will have 5,6 or more halfcycles depnding on its Q factor.
A couple of possibilities: (1) The device is damaged - say shorted turns, but I'd expect a much lower figure in that case. (2) Its distributed capacitance is very large so the SRF is below 100 Hz - seems unlikely that's a capacitance large than 168 nF. (3) More likely: the excitation is too high causing core saturation or the core has been magnetized by excessive DC at some point. I'd remeasure the DCR using the 1st instrument in DCR mode, not R mode - they are completely different. Assuming the DCR is within spec, try degaussing the core by connecting a largish charged capacitor across it and let the ring down remove the remanence (watch on scope - good video subject!). If you happen to have an Z-measuring instrument that can be automated sweep it from sub-1 Hz to 1 kHz and fit a model to the magnitude and phase measured... You can do this manually with a signal generator and the scope, but it is much easier with a nice impedance meter and some SCPI commands. Some Z-meters let you do DC current biasing during testing which is also informative with inductors.
I always understood chokes resist voltage change, the value of the chokes ability to do that is tied directly to the current moving through the device. Not the audio frequency in this instance
it is an inductive pressure sensor, you must take it to high altitude, and at height indicated on that case, it will show the inductance indicated on that case
1962….? Check it with a gieger counter? Ionizing radiation could have changed the properties of the copper inductor. Or maybe you’re above 18,000 ft😎. If you Google freed and the part number, there’s documentation on it
Have you checked the terminals to case. It may have been subject to excessive voltage and current and the thing arc out. If some turns are short out I would expect the d.c. resistance to go down. Its not 75 ohm impedance so the resistance has to be measured with d.c. Can you hi-pot it? More testing needs to be done to figure this out. BTW love your shop! 73's
I think you need to keysight your henries instead of measuring your farads 🤣 Pure guess to steelman for Freed Co, the 10V test signal is quite large compared to anything you'd normally test with nowadays. Although no idea if that would make a big difference or no difference. Not sure if you can change the voltage test signal in the top right of your bridge (also slow down the oscillator)?
You're going to have an issue with inter turn capacitance. They're using a lot of turns with a relatively small wire. The way to test these are to measure the resistance with a DC and feed them with a variable frequency generator that has an internal impedance equal to the DC resistance. Measure the voltage across the inductor with an oscilloscope and vary the frequency until the voltage across the inductor is half the open circuit voltage. Use inductance math to calculate the inductance. Some of these are swinging chokes and have a smaller impedance at high currents so keep the test voltage low as necessary.
And your saying sometimes farads...sometimes..... There was a mil spec...that would call out the test frequency... I think you can hit it with a square wave....the rise in current over time can tell you the inductance..... With the coil of wire...to have that much dc resistance...the wound wire must be super fine....
while it is often difficult to measure large inductances, in this case I think the device is defective. The reason being that the max R is 75ohm but you measure over 150,...I suggest opening it up and making another video. "Everybody Loves Tearing Open Parts" ;-}......
Freed at some point became ETC - Electronic Transformer Corp, 460 Totowa Ave, Paterson NJ. Still there, they have a website, and their building at that address is appropriately vintage.
maybe make a LC resonant tank with a known cap value and excite it with 60Hz signal and check the ringings on a scope to calculate the frequency that will give the inductor value.
Not only do you need 60 Hz, but you need the 10v magnetizing current specified on the label. Professional LCR meters allow a DC voltage of your choice across the device being tested.
yes, that was a thought of mine, DC offset. I haven't played with that before. I have and LCR bridge that will allow it but need external wires and supply.
Maybe someone put too much current through it once and permed the core? That might drop the inductance for small signals? Maybe you can fix it by running some AC current through it to get the core back to where it should be?
the explanation is simple. that choke was overloaded, developed internal short circuit between some layers. that's why it only shows 2 henryes and it was in the free pile.
There’s a new product I just happened upon called “Jumperless”. It’s a prototyping tool like a breadboard but without the need for jumper wires. It looks to good to be true. If you have the opportunity to review it, please do. It fit nicely alongside Chip o’ the Day and your product reviews are very helpful. Thanks!!
Looks very limited, I imagine it is a repurpose of an analog synthesizer patch panel. size, voltage range, and resistance make it near useless for me. www.tindie.com/products/architeuthisflux/jumperless/
That choke imposed a good challenge to many “modern “ LCR meter for its value with DC bias of 130 mA dc, high DCR and parasitic capacitance, you might have a better luck with an Old ESI meter, it work at 120 hz and up to 200 H.
I've finally taken the plunge and ordered an MSO5000 and HDO814, but I'm still without an LCR meter. Something I must seriously look into. I don't want to spend crazy amounts though and they seem to cost the earth. Re the strange readings, could the ceramic coating of the coil degraded over time perhaps?
Probably not ideal to be used in any mains power supply. Because aircraft electronics work on 400Hz AC. So the core in that choke may not have good characteristics for 60hz Since the DC resistance is so high, you probably need to crank the testing osc voltage to compensate for all that loss.
First off you need to learn the differance between Henrys and Farads. Second If this choke was tested a 60 Hz, then that's where you should test same. The reason that you weren't getting the correct values is due to changes in permeability, of the core, verses frequency. If the Freed company says it is 15 Henrys, then it's 15 Henrys. It didn't look like it had ever been soldered to therefor I would consider as new old stock. And it should test as advertised under the conditions described. It seems to me that you should do a bit more research before posting your. videos.
"it should test as advertised under the conditions described. " Indeed it should, but it didn't. It is extremely unlikely that a choke would be 15 Henries at 60 Hz but only 2 Henries at 100 Hz. It's *reactance* will increase with frequency; but the inductance isn't going to decline.
It was not tested under the conditions describe. The permeability also changes with frequency. Look at some permeability curves for common core materials. and see how they vary with frequency. Inductance is directly proportional to the permeability of the core. It goes down, so does the inductance. You can bet that Freed selected a core material that would optimize the inductance at 60 Hz.
@@peterayearst23 Fairly mild as RUclips critics go. Part of the appeal of this channel is we *share* in the research as it reveals itself, see some marvelous old test equipment; read comments from people who have various ideas about determining what's inside a little grey metal box.
Looks like Freed Transformer is still in business, but now based in Paterson NJ, now part of Electronic Transformer Corp.
The problem with your henries is the measurement frequency. The 15 Henries are there, you just don't see them, at frequencies around 100Hz. In order to actually measure the fundamental inductance you have to measure at significantly lower frequency. I deal with very large inductances every day and have a special HIOKI LCR meter that can even measure in the sub-Hz range. I often measure inductors around 15H at 0.5Hz or lower. You can also check the inductance via the step response by measuring the time constant of the coil and then calculating the inductance via the ohmic (DC!) resistance, L=Tau*R...
The choke could have been a filter choke in a power supply circuit that was overloaded and now has shorted turns. Use a .1mfd capacitor in series with the choke and connect your signal generator to the ends. Connect the scope to the center and adjust the generator for maximum signal. It should be near 130 hz.
Exactly. Treat it like a resonant circuit and solve for L. BINGO! 👍
Any thing new comming soon ? Good to see you glasslinger !!
@@rorymacleod8488 Fixing broken instruments. Be done soon and more videos will come.
Shorted turns would respond with much lower inductance, I suspect.
@@mr1enrollment Shorted turns can be almost any number of turns so the inductance can vary all over the place, from almost no effect to drastic decreases.
It is obvious to the most casual of observers that the 15H min spec is approximately 4 times the measured 2H and that 36,000 ft is twice the 18,000 ft rated altitude and since 4 is 2 squared and given that the Henry leakage function is parabolic the only conclusion one can draw is that this device was flown in the unpressurized hold of a commercial jetliner from the East coast to the West coast at some point in time and the lost Henry's are now floating around the sky inducing dangerous electromotive forces in unwary aircraft.
There are many ways for testing an inductance. You can also connect it to dc power supply and measure how fast the current rises (this method works if your choke has a gap, so it tolerates some amount of dc bias). Ofc, you should treat it as an RL circuit, with R part being dc resistance of the choke... But in my opinion the best piece of advice is given by glasslinger in comments. Try making a tank circuit with your choke and a known, high value cappacitor (small ones are not usable since their cappacitance will be comparable to the selfcapacitance of the choke, so you could not find the resonant frequency), connect the tank circuit to the scope and then hit the circuit with a somewhat high DC pulse. You will get decaying oscillations on your scope. From frequency you can deduce the L of the choke, and from number od oscillations (better to say, the decay constant) you can get some sense of health of the choke. If the choke has any shorted turns the oscillations will decay very very quick. At most , after two or three halfcycles. A good choke will have 5,6 or more halfcycles depnding on its Q factor.
The video isn’t done until you open the inductor up.
You know what we want. 😀
You could do a ring test on it. Maybe it has shorted turns. diodegonewild has a video about that
You could try a function generator and a scope to measure it's inductance at 60Hz.
A couple of possibilities: (1) The device is damaged - say shorted turns, but I'd expect a much lower figure in that case. (2) Its distributed capacitance is very large so the SRF is below 100 Hz - seems unlikely that's a capacitance large than 168 nF. (3) More likely: the excitation is too high causing core saturation or the core has been magnetized by excessive DC at some point. I'd remeasure the DCR using the 1st instrument in DCR mode, not R mode - they are completely different. Assuming the DCR is within spec, try degaussing the core by connecting a largish charged capacitor across it and let the ring down remove the remanence (watch on scope - good video subject!). If you happen to have an Z-measuring instrument that can be automated sweep it from sub-1 Hz to 1 kHz and fit a model to the magnitude and phase measured... You can do this manually with a signal generator and the scope, but it is much easier with a nice impedance meter and some SCPI commands. Some Z-meters let you do DC current biasing during testing which is also informative with inductors.
I always understood chokes resist voltage change, the value of the chokes ability to do that is tied directly to the current moving through the device. Not the audio frequency in this instance
it is an inductive pressure sensor, you must take it to high altitude, and at height indicated on that case, it will show the inductance indicated on that case
Maybe IMSAI Guy has a vacuum chamber.
@@dimBulb5 sure she has
1962….? Check it with a gieger counter? Ionizing radiation could have changed the properties of the copper inductor.
Or maybe you’re above 18,000 ft😎. If you Google freed and the part number, there’s documentation on it
Have you checked the terminals to case. It may have been subject to excessive voltage and current and the thing arc out. If some turns are short out I would expect
the d.c. resistance to go down. Its not 75 ohm impedance so the resistance has to be measured with d.c. Can you hi-pot it? More testing needs to be done to figure this out. BTW love your shop!
73's
I love the comment section. Most of grand masters are here 👏🙏
The resistance measurement should be DC. It is specified that way: DCR
I think you need to keysight your henries instead of measuring your farads 🤣 Pure guess to steelman for Freed Co, the 10V test signal is quite large compared to anything you'd normally test with nowadays. Although no idea if that would make a big difference or no difference. Not sure if you can change the voltage test signal in the top right of your bridge (also slow down the oscillator)?
You're going to have an issue with inter turn capacitance. They're using a lot of turns with a relatively small wire. The way to test these are to measure the resistance with a DC and feed them with a variable frequency generator that has an internal impedance equal to the DC resistance. Measure the voltage across the inductor with an oscilloscope and vary the frequency until the voltage across the inductor is half the open circuit voltage. Use inductance math to calculate the inductance. Some of these are swinging chokes and have a smaller impedance at high currents so keep the test voltage low as necessary.
And your saying sometimes farads...sometimes.....
There was a mil spec...that would call out the test frequency...
I think you can hit it with a square wave....the rise in current over time can tell you the inductance.....
With the coil of wire...to have that much dc resistance...the wound wire must be super fine....
while it is often difficult to measure large inductances, in this case I think the device is defective. The reason being that the max R is 75ohm but you measure over 150,...I suggest opening it up and making another video. "Everybody Loves Tearing Open Parts" ;-}......
I like the tank circuit idea.
Freed at some point became ETC - Electronic Transformer Corp, 460 Totowa Ave, Paterson NJ. Still there, they have a website, and their building at that address is appropriately vintage.
wasn't me! I didn't Hurtz Henry's feelings! last I heard, he was all charged up & ready 2 go! test his potential !!
maybe make a LC resonant tank with a known cap value and excite it with 60Hz signal and check the ringings on a scope to calculate the frequency that will give the inductor value.
Not only do you need 60 Hz, but you need the 10v magnetizing current specified on the label. Professional LCR meters allow a DC voltage of your choice across the device being tested.
yes, that was a thought of mine, DC offset. I haven't played with that before. I have and LCR bridge that will allow it but need external wires and supply.
Maybe someone put too much current through it once and permed the core? That might drop the inductance for small signals? Maybe you can fix it by running some AC current through it to get the core back to where it should be?
Freed? Ask Fran, she might remember the company.
Nice choke, though it seems small-ish for 15H. Still a good thing to have in a tube amp.
that is probably what someone thought and put in more than 130mA
@@IMSAIGuy well, that could happen if going for two 6L6 or bigger... Smaller amps, like a pair of EL84s wouldn't even reach that.
Wow I had not seen a ZM-11 since my Navy Days... We used to cal them on the tender, brought back old memories... Thanks for you vids...
I've done several videos on the ZM11/U here is one: ruclips.net/video/NWm7yu1W3v0/видео.htmlsi=ThpCDV-MAiXI9aIa
the explanation is simple. that choke was overloaded, developed internal short circuit between some layers. that's why it only shows 2 henryes and it was in the free pile.
Did you test the DC resistance of 75 ohms ?...cheers.
I remember it didn't match. I guess that was a clue, I think it was lower
Based on its DC resistance of 75Ω the 10V quoted @ 60Hz is the voltage drop when it's passing the max 130mA DC Theoretically it would be 133.3mA
Imma say that it's obviously busted, so let's crack it open to see what all the hubbub is about. Fun!
An inductor that big....the test frequency needs to be much lower....
Gov't surplus, maybe out of spec. Looks small for 15H. "Take it apart", like Dave Jones says!
Shorted turns !
If it is intended for use in aerial applications, it should be specified for 400Hz, am I right?
There’s a new product I just happened upon called “Jumperless”. It’s a prototyping tool like a breadboard but without the need for jumper wires. It looks to good to be true. If you have the opportunity to review it, please do. It fit nicely alongside Chip o’ the Day and your product reviews are very helpful. Thanks!!
Looks very limited, I imagine it is a repurpose of an analog synthesizer patch panel. size, voltage range, and resistance make it near useless for me.
www.tindie.com/products/architeuthisflux/jumperless/
That choke imposed a good challenge to many “modern “ LCR meter for its value with DC bias of 130 mA dc, high DCR and parasitic capacitance, you might have a better luck with an
Old ESI meter, it work at 120 hz and up to 200 H.
Henry, not Farad ;-)
they are both fine fellows
@@IMSAIGuy Hehe ;-)
Seems like a measurement job for the turbo encabulator.
I've finally taken the plunge and ordered an MSO5000 and HDO814, but I'm still without an LCR meter. Something I must seriously look into. I don't want to spend crazy amounts though and they seem to cost the earth. Re the strange readings, could the ceramic coating of the coil degraded over time perhaps?
trust your testers, its been toasted
Probably not ideal to be used in any mains power supply. Because aircraft electronics work on 400Hz AC. So the core in that choke may not have good characteristics for 60hz
Since the DC resistance is so high, you probably need to crank the testing osc voltage to compensate for all that loss.
Another day older and deeper in debt
I haven’t watched the video yet, but
Is it Altitude sensitive? Are you heneries hiding in the clouds? 😂
Didn't it read 10V - 60Hz? I'm guessing the 10V AC factors into the measurement results?
Maybe it's 1.5 Henry?
i wonder, if it was used on a plane or a ship where 400Hz?
You function-selected L(Q). What's L(D)?
it is for parallel or series testing with addition of using the D knob or Q knob: ruclips.net/video/NWm7yu1W3v0/видео.htmlsi=10lOAzIbLPlw-_ZH
Why are you saying 15 Farads.....this is an inductor not a capacitor????
It was an error.....errors do occur.....do I get a paper hat.
Please follow up - now I want to know! :)
I think your frequency is too high.
HENRY! not FARAD. You're killing me. You keep saying FARAD!
Check if coil have 75ohms, if not, coil are short.
15 henry min... or 1.5henry min... typo?
5:12
First off you need to learn the differance between Henrys and Farads. Second If this choke was tested a 60 Hz, then that's where you should test same. The reason that you weren't getting the correct values is due to changes in permeability, of the core, verses frequency. If the Freed company says it is 15 Henrys, then it's 15 Henrys. It didn't look like it had ever been soldered to therefor I would consider as new old stock. And it should test as advertised under the conditions described.
It seems to me that you should do a bit more research before posting your. videos.
"it should test as advertised under the conditions described. "
Indeed it should, but it didn't. It is extremely unlikely that a choke would be 15 Henries at 60 Hz but only 2 Henries at 100 Hz. It's *reactance* will increase with frequency; but the inductance isn't going to decline.
It was not tested under the conditions describe. The permeability also changes with frequency. Look at some permeability curves for common core materials. and see how they vary with frequency. Inductance is directly proportional to the permeability of the core. It goes down, so does the inductance. You can bet that Freed selected a core material that would optimize the inductance at 60 Hz.
Your "bit more research " comment I think is out of line. Lighten up.
@@peterayearst23 Fairly mild as RUclips critics go. Part of the appeal of this channel is we *share* in the research as it reveals itself, see some marvelous old test equipment; read comments from people who have various ideas about determining what's inside a little grey metal box.