From: mynamespacedbydots@xs4all.nl   
      
   "Phil Allison"  wrote in message   
   news:aes634Fhmh9U1@mid.individual.net...   
   >   
   > "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   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)