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#1
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Mystery transformer
Some time ago I found a small transformer in the junkbox.
It looks old, like from the forties or fifties era. I don't remember where it came from or was cannabilized from. Anyway, today I took the trouble to measure it. Winding W1: Rdc = 32ohm Saturation at about 50V, W2 open Inductance 8.82H @ 10V/50Hz Inductance 6.58H @ 10V/100Hz Winding W2: Rdc = 29ohm Saturation at about 37V, W1 open Inductance 5.36H @ 10V/50Hz Inductance 4.11H @ 10V/100Hz Winding ratio N = 1.34 Impedance ratio = 1.79 F-response -3dB @ 27kHz with a 600ohm load on W2 +3dB @ about 80kHz with (almost) no load on W2 +22dB @ 186kHz resonance with (almost) no load on W2 Iron lamination dimensions 48x40x20mm It's "tarred" and has NO airgap Beside end taps, no additional taps on W1 and W2 What could the purpose have been? Anybody any idea??? TIA & regards, Gio |
#2
Posted to rec.audio.tubes
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Mystery transformer
"GRe" wrote in message ... Some time ago I found a small transformer in the junkbox. It looks old, like from the forties or fifties era. I don't remember where it came from or was cannabilized from. Anyway, today I took the trouble to measure it. Winding W1: Rdc = 32ohm Saturation at about 50V, W2 open Inductance 8.82H @ 10V/50Hz Inductance 6.58H @ 10V/100Hz Winding W2: Rdc = 29ohm Saturation at about 37V, W1 open Inductance 5.36H @ 10V/50Hz Inductance 4.11H @ 10V/100Hz Winding ratio N = 1.34 Impedance ratio = 1.79 F-response -3dB @ 27kHz with a 600ohm load on W2 +3dB @ about 80kHz with (almost) no load on W2 +22dB @ 186kHz resonance with (almost) no load on W2 Iron lamination dimensions 48x40x20mm It's "tarred" and has NO airgap Beside end taps, no additional taps on W1 and W2 What could the purpose have been? Anybody any idea??? Telephone application? |
#3
Posted to rec.audio.tubes
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Mystery transformer
On Wednesday, October 24, 2012 4:51:09 PM UTC-4, Charles wrote:
"GRe" wrote in message ... Some time ago I found a small transformer in the junkbox. It looks old, like from the forties or fifties era. I don't remember where it came from or was cannabilized from. Anyway, today I took the trouble to measure it. Winding W1: Rdc = 32ohm Saturation at about 50V, W2 open Inductance 8.82H @ 10V/50Hz Inductance 6.58H @ 10V/100Hz Winding W2: Rdc = 29ohm Saturation at about 37V, W1 open Inductance 5.36H @ 10V/50Hz Inductance 4.11H @ 10V/100Hz Winding ratio N = 1.34 Impedance ratio = 1.79 F-response -3dB @ 27kHz with a 600ohm load on W2 +3dB @ about 80kHz with (almost) no load on W2 +22dB @ 186kHz resonance with (almost) no load on W2 Iron lamination dimensions 48x40x20mm It's "tarred" and has NO airgap Beside end taps, no additional taps on W1 and W2 What could the purpose have been? Anybody any idea??? Telephone application? If it was from telco- then most likely to match 600 to 900 . |
#4
Posted to rec.audio.tubes
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Mystery transformer
"GRe" Winding W1: Rdc = 32ohm Saturation at about 50V, W2 open Inductance 8.82H @ 10V/50Hz Inductance 6.58H @ 10V/100Hz Winding W2: Rdc = 29ohm Saturation at about 37V, W1 open Inductance 5.36H @ 10V/50Hz Inductance 4.11H @ 10V/100Hz Winding ratio N = 1.34 Impedance ratio = 1.79 F-response -3dB @ 27kHz with a 600ohm load on W2 +3dB @ about 80kHz with (almost) no load on W2 +22dB @ 186kHz resonance with (almost) no load on W2 Iron lamination dimensions 48x40x20mm It's "tarred" and has NO airgap Beside end taps, no additional taps on W1 and W2 What could the purpose have been? Anybody any idea??? ** Almost certainly it's a high quality, 600 ohms line driving transformer. The primary impedance is about 1000 ohms and so suits cathode drive from a small power tube, via a coupling capacitor. Max operating level is about 10 volts rms, with 13 volts drive on the primary. Line receiving versions were usually fitted into a ( mu-metal) shielding can. .... Phil |
#5
Posted to rec.audio.tubes
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Mystery transformer
"Charles" wrote in message ... "GRe" wrote in message ... Some time ago I found a small transformer in the junkbox. It looks old, like from the forties or fifties era. I don't remember where it came from or was cannabilized from. Anyway, today I took the trouble to measure it. Winding W1: Rdc = 32ohm Saturation at about 50V, W2 open Inductance 8.82H @ 10V/50Hz Inductance 6.58H @ 10V/100Hz Winding W2: Rdc = 29ohm Saturation at about 37V, W1 open Inductance 5.36H @ 10V/50Hz Inductance 4.11H @ 10V/100Hz Winding ratio N = 1.34 Impedance ratio = 1.79 F-response -3dB @ 27kHz with a 600ohm load on W2 +3dB @ about 80kHz with (almost) no load on W2 +22dB @ 186kHz resonance with (almost) no load on W2 Iron lamination dimensions 48x40x20mm It's "tarred" and has NO airgap Beside end taps, no additional taps on W1 and W2 What could the purpose have been? Anybody any idea??? Telephone application? Could be! Maybe Western Electric? Not mentioned in yesterday's post; there is a print in white characters on top of the transformer. Print: WE1612?? 6 420 The last two characters of the first line are too vague to read. Do you know they used indification no's with "WExxxx"? Regards, Gio |
#6
Posted to rec.audio.tubes
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Mystery transformer
"Phil Allison" wrote in message ... "GRe" Winding W1: Rdc = 32ohm Saturation at about 50V, W2 open Inductance 8.82H @ 10V/50Hz Inductance 6.58H @ 10V/100Hz Winding W2: Rdc = 29ohm Saturation at about 37V, W1 open Inductance 5.36H @ 10V/50Hz Inductance 4.11H @ 10V/100Hz Winding ratio N = 1.34 Impedance ratio = 1.79 F-response -3dB @ 27kHz with a 600ohm load on W2 +3dB @ about 80kHz with (almost) no load on W2 +22dB @ 186kHz resonance with (almost) no load on W2 Iron lamination dimensions 48x40x20mm It's "tarred" and has NO airgap Beside end taps, no additional taps on W1 and W2 What could the purpose have been? Anybody any idea??? ** Almost certainly it's a high quality, 600 ohms line driving transformer. The primary impedance is about 1000 ohms and so suits cathode drive from a small power tube, via a coupling capacitor. Max operating level is about 10 volts rms, with 13 volts drive on the primary. Line receiving versions were usually fitted into a ( mu-metal) shielding can. ... Phil Sounds like a bull's eye shot to me! With a line transformer application in mind I did some more tests. Inductance at -20dB steps: 8.8H @ 10V/50Hz (XL= 2.8Kohm) 3.4H @ 1.0V/50Hz (XL= 1.1Kohm) 1.6H @ 0.1V/50Hz (XL= 500 ohm) Z-total about 450ohm 0.9H @ 10mV/50Hz (XL= 280 ohm) Z-total about 270ohm 2.4H @ 10V/1kHz (XL= 15Kohm) 1.2H @ 1.0V/1kHz (XL= 7.5Kohm) 0.9H @ 0.1V/1kHz (XL= 5.6Kohm) 0.5H @ 10mV/1kHz (XL= 3.1Kohm) Looks like impedances are OK with a possible exception for 50Hz/.1V/10mV where XL parallel to the reflected 600ohm termination are lowish, about 450 & 270ohm. Would this imply a lower-R termination for more constant Z to the driver? Is a lowish impedance at low frequency & voltage of much significance regarding the low output impedance of a cathode follower/driver? Square wave test, Vi= 10Vpp/10kHz: Rise time at W2 = 14µS with a 600ohm load Rise time at W2 = 2µS with a 3600ohm load Square wave test, Vi= 10Vpp/50Hz: W2 droop about 7% at the trailing edge vs. leading edge, 600ohm load W2 droop also about 7% at the trailing edge vs. leading edge, 3600 ohm load Because of the 14µS rise time with 600ohm load, while without load significant ringing is present I wondered if a higher resistance would do better. Optimum was found with a 3600ohm load, almost no over- or undershoot. With the 3600ohm load the -3dB point shifted to about 175kHz. Would this imply a higher-R termination for a better signal transfer? Does the above data confirm application as a 600ohm line driver or does it suggest something else? Regards & TIA, Gio |
#7
Posted to rec.audio.tubes
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Mystery transformer
On Sun, 28 Oct 2012 16:29:16 +0100, "GRe"
wrote: "Phil Allison" wrote in message ... "GRe" Winding W1: Rdc = 32ohm Saturation at about 50V, W2 open Inductance 8.82H @ 10V/50Hz Inductance 6.58H @ 10V/100Hz Winding W2: Rdc = 29ohm Saturation at about 37V, W1 open Inductance 5.36H @ 10V/50Hz Inductance 4.11H @ 10V/100Hz Winding ratio N = 1.34 Impedance ratio = 1.79 F-response -3dB @ 27kHz with a 600ohm load on W2 +3dB @ about 80kHz with (almost) no load on W2 +22dB @ 186kHz resonance with (almost) no load on W2 Iron lamination dimensions 48x40x20mm It's "tarred" and has NO airgap Beside end taps, no additional taps on W1 and W2 What could the purpose have been? Anybody any idea??? ** Almost certainly it's a high quality, 600 ohms line driving transformer. The primary impedance is about 1000 ohms and so suits cathode drive from a small power tube, via a coupling capacitor. Max operating level is about 10 volts rms, with 13 volts drive on the primary. Line receiving versions were usually fitted into a ( mu-metal) shielding can. ... Phil Sounds like a bull's eye shot to me! With a line transformer application in mind I did some more tests. Inductance at -20dB steps: 8.8H @ 10V/50Hz (XL= 2.8Kohm) 3.4H @ 1.0V/50Hz (XL= 1.1Kohm) 1.6H @ 0.1V/50Hz (XL= 500 ohm) Z-total about 450ohm 0.9H @ 10mV/50Hz (XL= 280 ohm) Z-total about 270ohm 2.4H @ 10V/1kHz (XL= 15Kohm) 1.2H @ 1.0V/1kHz (XL= 7.5Kohm) 0.9H @ 0.1V/1kHz (XL= 5.6Kohm) 0.5H @ 10mV/1kHz (XL= 3.1Kohm) Looks like impedances are OK with a possible exception for 50Hz/.1V/10mV where XL parallel to the reflected 600ohm termination are lowish, about 450 & 270ohm. Would this imply a lower-R termination for more constant Z to the driver? Is a lowish impedance at low frequency & voltage of much significance regarding the low output impedance of a cathode follower/driver? Square wave test, Vi= 10Vpp/10kHz: Rise time at W2 = 14µS with a 600ohm load Rise time at W2 = 2µS with a 3600ohm load Square wave test, Vi= 10Vpp/50Hz: W2 droop about 7% at the trailing edge vs. leading edge, 600ohm load W2 droop also about 7% at the trailing edge vs. leading edge, 3600 ohm load Because of the 14µS rise time with 600ohm load, while without load significant ringing is present I wondered if a higher resistance would do better. Optimum was found with a 3600ohm load, almost no over- or undershoot. With the 3600ohm load the -3dB point shifted to about 175kHz. Would this imply a higher-R termination for a better signal transfer? Does the above data confirm application as a 600ohm line driver or does it suggest something else? Regards & TIA, Gio Could you explain these tests in a little more detail? I'm not sure why the inductance appears to be dependent on the voltage. d |
#8
Posted to rec.audio.tubes
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Mystery transformer
"GRe" "Phil Allison" "GRe" ** Almost certainly it's a high quality, 600 ohms line driving transformer. The primary impedance is about 1000 ohms and so suits cathode drive from a small power tube, via a coupling capacitor. Max operating level is about 10 volts rms, with 13 volts drive on the primary. Line receiving versions were usually fitted into a ( mu-metal) shielding can. Sounds like a bull's eye shot to me! With a line transformer application in mind I did some more tests. ** You are wasting your time with irrelevant tests. The tranny is intended to be driven from a low impedance source ( circa 50 ohms) and that tends to irons out effects due to low magnetisation. You need a THD meter to make sense of what matters and what does not. ..... Phil |
#9
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Mystery transformer
"Don Pearce" Could you explain these tests in a little more detail? I'm not sure why the inductance appears to be dependent on the voltage. It's due to hysteresis losses of ferromagnetic materials like the lamination in transformers. Take f.e. a mains transformer and measure the current trough the primary, while the secondary is open: 1) at mains voltage, f.e. 230Vac 2) at about 1/10 of the first, f.e. 24Vac. Calculate Z from Vac/Iac and XL from Sqrt(Z^2 - Rdc^2). Than calculate L from XL/(2.pi.f) Usually Rdc can be ignored, so XL practically equals Z. 3) you will find two quite different figures for the inductance. Gio |
#10
Posted to rec.audio.tubes
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Mystery transformer
On Mon, 29 Oct 2012 17:05:25 +0100, "GRe"
wrote: "Don Pearce" Could you explain these tests in a little more detail? I'm not sure why the inductance appears to be dependent on the voltage. It's due to hysteresis losses of ferromagnetic materials like the lamination in transformers. Take f.e. a mains transformer and measure the current trough the primary, while the secondary is open: 1) at mains voltage, f.e. 230Vac 2) at about 1/10 of the first, f.e. 24Vac. Calculate Z from Vac/Iac and XL from Sqrt(Z^2 - Rdc^2). Than calculate L from XL/(2.pi.f) Usually Rdc can be ignored, so XL practically equals Z. 3) you will find two quite different figures for the inductance. Gio But in your numbers, the inductance is increasing as the voltage increases. At higher voltage, the current should be higher, so the core would be more saturated, so the inductance should decrease, not increase. I think maybe you need to check your calculations. d |
#11
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Mystery transformer
"GRe" "Don Pearce" Could you explain these tests in a little more detail? I'm not sure why the inductance appears to be dependent on the voltage. It's due to hysteresis losses of ferromagnetic materials like the lamination in transformers. ** You have made a big mistake by separating Don's Q from the original context. Take f.e. a mains transformer and measure the current trough the primary, ** Irrelevant to the falling L value at lower levels in your tests. That has to do with falling permeability of the core at low I mags. Odds on the core is made of ordinary transformer steel rather than Mu-metal or similar. ..... Phil |
#12
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Mystery transformer
"Phil Allison" You need a THD meter to make sense of what matters and what does not. Input f/V/THD Output THD (600ohm terminated) 1kHz/1.0V/0.075% 0.082% 1kHz/3.6V/0.086% 0.101% 3.6V is the max. output for the audio generator. Can one simply substract THD Out/In numbers to gain THD for the transformer only? Gio |
#13
Posted to rec.audio.tubes
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Mystery transformer
"GRe" "Phil Allison" You need a THD meter to make sense of what matters and what does not. Input f/V/THD Output THD (600ohm terminated) 1kHz/1.0V/0.075% 0.082% 1kHz/3.6V/0.086% 0.101% 3.6V is the max. output for the audio generator. ** You need to use a much lower frequency. Transformer non linearity is concentrated at the low end of the audio band. Can one simply substract THD Out/In numbers to gain THD for the transformer only? ** To a rough approximation only. The figures quoted above suggest the tranny is adding almost nothing. PLUS it is crucial the source impedance be low - like 50 or 100 ohms. Easy way is to use one channel of a good hi-fi amplifier to buffer the output of the generator and drop the impedance to near zero. ..... Phil |
#14
Posted to rec.audio.tubes
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Mystery transformer
"Phil Allison" wrote in message ... "GRe" "Phil Allison" You need a THD meter to make sense of what matters and what does not. Input f/V/THD Output THD (600ohm terminated) 1kHz/1.0V/0.075% 0.082% 1kHz/3.6V/0.086% 0.101% 3.6V is the max. output for the audio generator. ** You need to use a much lower frequency. Transformer non linearity is concentrated at the low end of the audio band. I used the function generator HV-output(600ohm) for this test. Input f/V/THD Output THD (600ohm terminated) 200Hz/10V/0.036% 0.049% 100Hz/10V/0.037% 0.077% 50Hz/10V/0.037% 0.170% 25Hz/10V/0.036% 0.442% So, per "rough approximation" about 0.4% added distortion at 25Hz/10V. Scoping the distortionmeter's output it looks like mainly 3H, but seems quite acceptable to me for that frequency and level. Can one simply substract THD Out/In numbers to gain THD for the transformer only? ** To a rough approximation only. The figures quoted above suggest the tranny is adding almost nothing. PLUS it is crucial the source impedance be low - like 50 or 100 ohms. In this case it does'nt seem to make a difference using the function generator 50ohm or 600ohm output, see below, so I used the latter for the tests as the max. Vout is about 14V vs. about 7V(unterminated). At 25Hz/5V/600ohm output, THDout - THDin = 0.307 - 0.034 = 0.273% At 25Hz/5V/ 50ohm output, THDout - THDin = 0.721 - 0.444 = 0.277% Easy way is to use one channel of a good hi-fi amplifier to buffer the output of the generator and drop the impedance to near zero. Only handy in the living room, not on the bench. Gio. |
#15
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Mystery transformer
"GRe"
"Phil Allison" You need a THD meter to make sense of what matters and what does not. Input f/V/THD Output THD (600ohm terminated) 1kHz/1.0V/0.075% 0.082% 1kHz/3.6V/0.086% 0.101% 3.6V is the max. output for the audio generator. ** You need to use a much lower frequency. Transformer non linearity is concentrated at the low end of the audio band. I used the function generator HV-output(600ohm) for this test. Input f/V/THD Output THD (600ohm terminated) 200Hz/10V/0.036% 0.049% 100Hz/10V/0.037% 0.077% 50Hz/10V/0.037% 0.170% 25Hz/10V/0.036% 0.442% ** No "function generator" I ever heard of has THD figures as low 0.036%. Post a link for the one you have. PLUS it is crucial the source impedance be low - like 50 or 100 ohms. In this case it does'nt seem to make a difference using the function generator 50ohm or 600ohm output, ** Something is very fishy with your testing and that generator. Easy way is to use one channel of a good hi-fi amplifier to buffer the output of the generator and drop the impedance to near zero. Only handy in the living room, not on the bench. ** Stop being such a PITA ****. I posted HOW to do it - whether YOU have such an amp handy or not is YOUR problem. What a tedious **** head. .... Phil |
#16
Posted to rec.audio.tubes
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Mystery transformer
"Phil Allison" Input f/V/THD Output THD (600ohm terminated) 200Hz/10V/0.036% 0.049% 100Hz/10V/0.037% 0.077% 50Hz/10V/0.037% 0.170% 25Hz/10V/0.036% 0.442% ** No "function generator" I ever heard of has THD figures as low 0.036%. Singular H spec. in the 10Hz-50kHz range is = -65dB (0.056%) for both outputs. Post a link for the one you have. That would disqualify your judgement. Gio |
#17
Posted to rec.audio.tubes
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Mystery transformer
"GRe" "Phil Allison" Input f/V/THD Output THD (600ohm terminated) 200Hz/10V/0.036% 0.049% 100Hz/10V/0.037% 0.077% 50Hz/10V/0.037% 0.170% 25Hz/10V/0.036% 0.442% ** No "function generator" I ever heard of has THD figures as low 0.036%. Singular H spec. ** Wot sort of bull**** is that ???? in the 10Hz-50kHz range is = -65dB (0.056%) for both outputs. ** Yawnnnnnn.... Post a link for the one you have. That would disqualify your judgement. ** OK - this dopey game is now over. You are just another trolling, ****ing idiot. **** OFF to HELL |
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