The DC resistances you measured, plus the information printed on the xfmr would certainly lead one to believe that pins 1-3 are the low impedance side, and pins
6-7 the high impedance side.Yet, when you shorted 1-3 and measured 6-7, you got 22 ohms, versus 220 ohms the other direction. This is very strange.
Can you make measurements at another frequency, say 1 kHz? Can you determine the self resonant frequency of the unit at either winding?
These measurements were performed at 2 khz. Maybe this evening I'll do one more round of measurements. I'll find resonant frequency. MikeK
........................................................................................................................ PLEASE note: I corrected the values above, 22ohm was actually 220 ohms, and I recalculated SQRT(Zis*Zio). Don't know how I got those wrong.
New set of measurements at 1 khz.
Measure the impedance at pins 1-3 with pins 6-7 shorted; call this Zis.
217 ohmsMeasure the impedance at pins 1-3 with pins 6-7 (and all others) open; call this Zio.
75,000 Ohms ~ 36* phase shiftCalculate SQRT(Zis*Zio). This is the image impedance at pins 1-3. This will be the impedance to which the transformer will be best matched at pins
1-3. 4034 OhmsMeasure the impedance at pins 6-7 with pins 1-3 shorted; call this Zis.
229 ohmsMeasure the impedance at pins 6-7 with pins 1-3 open; call this Zio.
77,000 ohms ~36* phase shiftCalculate SQRT(Zis*Zio). This is the image impedance at pins 6-7. This will be the impedance to which the transformer will be best matched at pins
6-7. 4119 ohmsSRF 568 khz pin1 to 3 SRF 730 khz pin 6 to 7 What do you make of that? Thanks, MikeK
These latest results suggest that the two windings you measured are almost in a
1:1 ratio. This is also consistent with another measurement you described where you applied 1 volt to a winding and measured 1 volt out at the other winding.I don't know how to reconcile these results with the diagram printed on the xfmr. It's very strange!!
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there could be a lot of capacitance between the windings messing with your measurements at 2 kHz.
Ground the case.
apply a low z source at a low freq like 60 Hz to the low Z winding.
measure the voltage across the low z winding with a differential measurement like a meter, or a scope set up with 2 channels to measure differential.
measure the voltage across the secondary the same way.
compute the turns ratio and z ratio is the sqr root
Mark
there could be a lot of capacitance between the windings messing with your measurements at 2 kHz.
Ground the case.
apply a low z source at a low freq like 60 Hz to the low Z winding.
measure the voltage across the low z winding with a differential measurement like a meter, or a scope set up with 2 channels to measure differential.
measure the voltage across the secondary the same way.
compute the turns ratio and z ratio is the sqr root
Mark
Hi Mark, I had not thought of grounding the shield. The transformer frequency spec was 1 khz to 8 khz +or-0.2db. I wish I would have tried this, but I have shipped the transformer back to the supplier. Thanks, MikeK
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