[R-390] line filter for EAC R390A

[Tisha Hayes]

I would not replace the line filter with another of the same vintage. There
are capacitors soldered into that bathtub that are prone to leakage after
40+ years of service.

What I have done is to replace the line filter with a hospital grade Corcom
filter like a 3EHQ series   http://www.corcom.com/Series/Medical/HQ/

This has a very similar footprint to the original filter but has much better
isolation characteristics than the original.

While you are at it, add a few 130 volt MOV's from line-ground,
neutral-ground, line-neutral and an inrush limiter like a CL-190.

>From time to time you can find the 3EHQ or 6EHQ line filters on Ebay for
$10-20 each.

When the R-390A was designed the greatest sources of interference would be
from other radio equipment or radars, the occasional fluorescent light
fixture or generator noise. Today it's computers, computers, computers, BPL,
wireless Ethernet, X10 home appliance controllers and el-cheapo fluorescent
bulbs.

For several years I worked as a compliance engineer doing design and testing
of products to meet FCC type acceptance. Eliminating radiated emissions,
longitudinal and metallic noise and RFI shielding was a big challenge.
Selecting a good line filter was a good place to start from.

-- 
Ms. Tisha Hayes