I just asked because the probe you use will add probably a 100pF extra capacity and will be influence the measurement.
The test of the three OT only in backward mode, no dc current, signal equivalent 1 and 10 watt on 6 ohm, primari ( acting as secondary) at 2500 ohm.
But I have done other test with also 700 ohm
The previous test with a sw tell us what we find here, regarding the inductance at low frequency and parasitic at high
The THD /Freq where the H is higher it is lower
In the past I have posted them
But I have done other test with also 700 ohm
The previous test with a sw tell us what we find here, regarding the inductance at low frequency and parasitic at high
The THD /Freq where the H is higher it is lower
In the past I have posted them
Here an examle of OT with Finemet for 300B done time ago
Finemet is Hitachi and the costs are hugh.
Backward mode, nodc.
Zs 750 ohm connected to primary now acting secondary, 59 Vrms = around 5 watt/750 ohm
The shape is a U but the real distortion in low freq is quite low
This is at 1 w/750 ohm, 27 volt rms
Better of course in both end
Finemet is Hitachi and the costs are hugh.
Backward mode, nodc.
Zs 750 ohm connected to primary now acting secondary, 59 Vrms = around 5 watt/750 ohm
The shape is a U but the real distortion in low freq is quite low
This is at 1 w/750 ohm, 27 volt rms
Better of course in both end
I understand that in these tests a power of 1w and 10w was injected secondarily but you did not specify how this is done because directly from the generator I don't think it is possible, however some analog generators could do this
I'm sorry, I forgot about the post #33, the method is correct and useful for OT verification. I use the same method but with a 10w class A amplifier with mosfet, 2-140000 Hz passband and with an SQW response similar to that of the generator
daanve,
I was wrong, it was late at night.
1, 4, 9, and 16 is the correct tap impedances.
Just like Sowter.
I mis-poke when I said 2 Ohms, it is 1 Ohm with all 4 windings in parallel.
I was wrong, it was late at night.
1, 4, 9, and 16 is the correct tap impedances.
Just like Sowter.
I mis-poke when I said 2 Ohms, it is 1 Ohm with all 4 windings in parallel.
50AE,
At 50Hz, the primary DCR is in series with the primary inductance.
With the primary driven at 1kHz, by a low impedance, and with the secondary open, the voltage ratio is extremely close to the actual turns ratio.
Testing at 50Hz, the inductance and series DCR usually gets in the way of an accurate turns ratio measurement.
You get the voltage ratio, but it includes the voltage losses of the DCR,
Of course lamination losses can also reduce the turns ratio measurement accuracy.
We all have our preferred measurement setups.
At 50Hz, the primary DCR is in series with the primary inductance.
With the primary driven at 1kHz, by a low impedance, and with the secondary open, the voltage ratio is extremely close to the actual turns ratio.
Testing at 50Hz, the inductance and series DCR usually gets in the way of an accurate turns ratio measurement.
You get the voltage ratio, but it includes the voltage losses of the DCR,
Of course lamination losses can also reduce the turns ratio measurement accuracy.
We all have our preferred measurement setups.
I don't know if that method is correct, it needs more verification. For example, I can't find a Sowter transformer with a frequency plot like Walter made. And which Hammond was used?
In attach a graph of a freq. response of one OT in normal mode (red) and reverse mode (blu)
The little differences on level is to see better the curves.
They are same
About trfos
The Sowter is SA8 that I bought for this tests directly from them. Around 250 £
The Hammond is 1627se also bought by me.
Walter
It seems to me that your measurements are not on par with the measurements from manufactures as Sowter and Hammond.
https://www.hammfg.com/files/parts/pdf/1627SEA.pdf?v=1697661945
Can you explain why you measured differently?
https://www.hammfg.com/files/parts/pdf/1627SEA.pdf?v=1697661945
Can you explain why you measured differently?
Ternopil,
Measurement reversability:
If you know about such things as passive high pass filters, passive low pass filters, attenuator pads, etc. . . .
Then you understand the ability of many electronics parts and assemblies that are completely, and accurately, reversible.
You merely change which is the input and which is the output.
Of course you have to use the appropriate driving impedance, and the appropriate load impedance, as well as the appropriate signal level at the driven end of the device.
Transformers are one device that also is reversible.
If it were not so, there would be no conservation of energy, and some of the test setup energy would end up in a parallel universe.
Electronic measurements and Electronic design are still wonderful, because much of the early applicable mathematics and physics still apply.
Thanks!
Measurement reversability:
If you know about such things as passive high pass filters, passive low pass filters, attenuator pads, etc. . . .
Then you understand the ability of many electronics parts and assemblies that are completely, and accurately, reversible.
You merely change which is the input and which is the output.
Of course you have to use the appropriate driving impedance, and the appropriate load impedance, as well as the appropriate signal level at the driven end of the device.
Transformers are one device that also is reversible.
If it were not so, there would be no conservation of energy, and some of the test setup energy would end up in a parallel universe.
Electronic measurements and Electronic design are still wonderful, because much of the early applicable mathematics and physics still apply.
Thanks!
@6A3sUMMER
My point is not specifically inverted or not inverted, but that the measurements differ from those of Sowter and Hammond. A measurement must be able to be verified by others with the same outcome, otherwise it is unreliable.
My point is not specifically inverted or not inverted, but that the measurements differ from those of Sowter and Hammond. A measurement must be able to be verified by others with the same outcome, otherwise it is unreliable.
Direct current can be injected into the secondary to measure the primary inductance, this current must be proportional to the transformation ratio but it is mandatory to use a CCS