Quote:
Originally Posted by Peter Wieck
David Hafler put copper bands on most of his solid state amp transformers. HK did it for some of theirs. Apparently (offered without factual reference) it is a combination shield and hum - audible - damper. It is called a "flux damper", and may be grounded to the secondary, or not.
Hope that helps.
Peter Wieck
Melrose Park, PA
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Thanx for your response Peter but it is an air cored cross over choke, not a transformer. And the copper band is a right angles to the winding so that coupling would be at a minimum.
We do see Faraday shields often used in PTs to minimize coupling both forward & reverse to the line. I once used a simple piece of steel sheet between at PT & OPT to reduce the incidental coupled hum component. Don't have any numbers on the hum reduction but the audible difference was significant.
Sofar that copper band is a mystery. I guess someone has a reason, we will see!!
Cheers to all, John L Stewart