[R-390] Mechanical Filter Repair

[John Kolb]

On Wed, 24 Jul 2002, Norman Ryan wrote:

> Do you know what the impedance should be?  I get similar DC resistances
> from input and output, thus expect impedance is the same each way.

What's the filter number? I have a number of data sheets, and
might be able to look it up.

I just measured an R-390A filter which is 100K Z at 50 ohms
in and out resistance. A F500Y-70, which is 1K input Z,
330 ohms output Z measured 40 ohms for both the input and
output side - just a rough measurement on a 260, but clearly
the resistance is not proportional to Z.

The R-390A filters, like most of the older filters designed
for tube applications were spec'ed for 100K Z. Newer filters
designed for solid state were most often 2K in and out.

John

> John Kolb wrote:
> > Just measured 2 open filters and a loose bobbin and got wire
> > diameters about 0.0062 and 0.0070 ("V and Y case filters),
> > which would be 34 or 35 gauge enameled wire.
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