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Old 10th June 2004, 06:35 PM   #1
stigla is offline stigla  Norway
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Hi!

I recently aquiered an obviously Vintage OPT from a flee marked. It's probably been used in a radio. I have measured it to be of a 5K:8 ratio.

The windings have many paper-interleavings, and is impregnated in wax. It really looks like a (relative) quality opt. I think I want to use it in a SE guitar amplifier with a 6V6.

One interesting thing though, is that it apparently does not have an Airgap, I can see no paper-interleaving between the E and the I parts of the core.

So, was it normal to use Parafeed in the Radio days? How can I find out if the OPT can pass any DC current?

Thanks;

-stigla
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Old 10th June 2004, 06:40 PM   #2
SY is offline SY  United States
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There are fancier ways to do it, but my inclination would be to rig it up with whatever small tube I had laying around (like an EL84), in triode for simplicity, then run a signal to the grid and see what comes out. If you've got a test bench with basic stuff like power supplies, sig generators, clip leads, and a scope, this should take less than an hour.
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Old 10th June 2004, 08:21 PM   #3
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Doesn't have to have paper in the core, usually all the Es and Is are grouped together rather than interleaved as in an AC transformer. Maybe a piece of cardboard between the Es and Is to add a little gap but it's not necessary if the current is low, which may very well be on a 6V6 SE OPT.

Tim
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