Output transformer ringing

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BluegrassDan

Well-known member
GDIY Supporter
Joined
Mar 17, 2009
Messages
514
Location
Elizabethton, TN
Hey guys,

Finally got an oscilloscope and function generator, and I'm finding some interesting things about my tube preamp. It appears the output transformer is ringing. (Edcor WSM 10k to 600 (4.1:1)

Is this due to improper loading of the transformer due to the oscilloscope leads, or is it an anomaly of the transformer? What should I do to remedy this?

Signal after coupling cap, before output transformer:




Signal following output transformer:

 
needs a simple termination like in "olden" days,
or a Zobel which is a bit more involved.
 

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  • 600_term.jpg
    600_term.jpg
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I would call this normal.
Looks similar to waveform generated by a ring tester. The waveform shows a good winding with high Q factor.
 
What's frequency response with and without the Zobel, with source impedance of 150 ohms, and with 600 ohm and bridging loads? The square wave test doesn't tell the whole story. And what was the square wave test frequency?
 


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