Dave Woolf wrote:

I am looking for a part for a Tektronix
491 spectrum analyzer. It is called the
RFI filter or the Low Pass 275 V AC Filter
The Tek part number as listed in my
service manual is 119-0095-00. It is a
metal can that on one end has the male
connector that the AC cord plugs into.
The other end feeds out the line voltage
to the internal fuses.

You can replace it with a stock Corcom EMI filter from Digi-Key.

The failure is interesting. At some AC
voltage around 105 - 110 volts there is
a breakdown and short that blows a 20 amp
circuit breaker. The short is not permanent
as I can turn the unit off/on and it will again
work below the above voltage. I know it is
the filter as this is the only thing that is
before the internal fuse which never blows.

This thing is a pi filter with an inductor inside and some shunt
capacitors. One of the capacitors is on the way out.

I have a work-around by running the unit
on a variac and keeping the voltage at
around 100 volts. But I am not sure how
long this will work, so I would like to
replace the filter.

Anyone know of a source?

Open it with a can opener and replace the ceramic caps.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."