01-06-2013, 07:37 AM
"Comes up once a month or so. Used to be marine and other beacons around IF frequency. Shielding no longer needed, but does no harm."
That answer also comes up every time
and is not accurate. The wire coil added to the cap was an effort to 'retune' it closer to the IF frequency for improved bypassing characteristics - usually between B-minus and chassis. The goal was to prevent undesirable feedback caused by floating 455kc on the B-minus line and the series-resonant circuit accomplished that more efficiently than the cap alone.
The old paper cap had a significant amount of self-inductance due to its construction. The new caps don't have this problem and don't need the remedy.
-Bill
That answer also comes up every time
and is not accurate. The wire coil added to the cap was an effort to 'retune' it closer to the IF frequency for improved bypassing characteristics - usually between B-minus and chassis. The goal was to prevent undesirable feedback caused by floating 455kc on the B-minus line and the series-resonant circuit accomplished that more efficiently than the cap alone.The old paper cap had a significant amount of self-inductance due to its construction. The new caps don't have this problem and don't need the remedy.
-Bill
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