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In Reply to: RE: Resistor on the interstage transformer posted by danlaudionut on August 20, 2015 at 21:16:38
What about a bifilar 1:1 IT ? I found with a dirt-cheap £30 Hammond 126B and also C models , adding a resistor worsened the measured response and also the sound . So I ran these devices wide open . Lundahls on the other hand , I had a different experience WRT the secondary resistor but these were for pushpull rather than SE useage
From my experience with the 126 , a lower driving Ra is preferred...
The impedence specifications I always find misleading with IT's . What manufacturers should always specify is the ratio and primary inductance along with ungapped DC current rather than this generalised 'impedence' thing .
Al
Follow Ups:
Best is to measure the transformer. Most manufactures don't give datasheet so its a bit gambling...Bifilair 1:1 are mostly excelent transformers but, you have to use very good wires for good isolation. Standard transformer wires are not the best wires.
If a transformer has some resonance problems a resistor could help but for a 1:1 i would say the transformers sucks .
Edits: 08/24/15
The insulation rating is one thing Hammond fails to quote on the specs . I have , so far only used tubes such as 6S45 , EC8010 , 4P1L and type 46 , with these IT's . I wouldn't want to risk an 845 with -120V bias one end and driver HT of 400V on the other .
Al
You could do a little experiment with the wires.
If you can solder them (at temperture 450 degrees Celcius) the wire is probebly a normal transformer wire single coated. I wouldn't try to high voltage differance on those wires.
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