08-02-2011, 08:42 AM
Most AC/DC radios have one safety cap connected across the line, while most AC-only (those which use a power transformer) sets use two safety caps, each one connected between one side of the line and chassis ground.
Follow the link which Greg (gvel) gave you to the page on the Just Radios site. There is some very good information there.
The first illustration on that page shows how two line-to-ground safety caps are connected in an AC-only radio with a power transformer.
The second illustration shows an across-the-line cap in an AC/DC set.
Philco did not start using line-to-ground caps until the model 111 came out in January 1931. The 87 did not have line-to-ground caps originally, although it certainly won't hurt anything to add them. As the text states, the use of these will help filter out interference in the AC line. Be aware, though, that the use of these will cause the chassis of your 87 to have some AC potential on it. The current, however, is minuscule.
Follow the link which Greg (gvel) gave you to the page on the Just Radios site. There is some very good information there.
The first illustration on that page shows how two line-to-ground safety caps are connected in an AC-only radio with a power transformer.
The second illustration shows an across-the-line cap in an AC/DC set.
Philco did not start using line-to-ground caps until the model 111 came out in January 1931. The 87 did not have line-to-ground caps originally, although it certainly won't hurt anything to add them. As the text states, the use of these will help filter out interference in the AC line. Be aware, though, that the use of these will cause the chassis of your 87 to have some AC potential on it. The current, however, is minuscule.
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Ron Ramirez
Ferdinand IN
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