[RFI] W3NQN AC Filter Notes

Tim Duffy Tim Duffy <tduffy@sygnet.com>
Tue, 09 May 2000 19:02:24 -0500

The W3NQN AC line filter is available from W3NQN for $75.00. Contact
W3NQN at his callbook address. He does not have EMAIL and there is no
WEB site for information.

I will have a small number of these filters available at Dayton for sale
as a favor to Ed. I will be in the Crowne Plaza Contest Super Suite on
Thursday, Friday and Saturday nights. If you want one of these filters
from me at Dayton, I suggest you send me an EMAIL to reserve one (or
more) as I expect they will sell quickly.
The price at Dayton is the same price you can get from Ed. I make
nothing on the sale of the filters, I am doing Ed a favor because he
developed the filter from my specifications which solved all of my AC
related RFI issues both in the shack and on my neighbors computers and

I use one of these filters on every transceiver (12 stations) and every
computer (13) in my station. They give tremendous isolation from radio
to radio and insure that any computer power supply noise is attenuated
as well.

Some of the features of the W3NQN 7 amp differential mode powerline
filter are:

Optimum shielding is provided to minimize line cord radiation by use of
a three-wire powerline cord with a combination of braid and foil

Four .01 uF/250 VAC and one .047 oF/250 VAC, 50/60 Hz Class Y
polyester-film capacitors are used in this filter. These capacitors are
Roederstein Series F1710 Radio Interference Suppressor capacitors and
both are rated for across-the-line and line bypass applications.

Two Panasonic Class X-Y metallized-film Interference Suppressor
Capacitors are used for the input and output across the line filtering.
This capacitor is a type ECQ-UF, .01 uF/250 VAC,  rated for
across-the-line applications.

Four 55 uH powdered-iron toroidal inductors (two per line) are used for
optimum powerline differential mode filtering and are conservatively
rated for a line current of seven amperes.

The braid and foil shields and third-wire ground are maintained through
the filter case from the IEC female receptacle to the NEMA three-prong
AC plug.

The filter replaces your power cord completely. The AC input cable is
about 6 ft long and the output is about 6 inches long.

The 115 VAC leakage current measured through a 1500- resistor from the
filter case to ground is less than one milliampere.

The voltage drop between the filter input and output at a load current
of seven amperes is about one volt.

A three-prong female-to-two-prong-male adapter ("cheater plug") is
included if you want to break the shield at your 115 VAC power
connection point to eliminate a possible ground loop caused by two
different grounds (AC service and your station ground) via the shield.
The load being filtered must have a good RF ground for optimum filter

The chassis cover is secured to the aluminum case with four machine
screws into matching 4-40 PEM nuts.

I hope this answers all of the questions that I received concerning this

Tim K3LR

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