[GRe]

"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