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7.
Following additional guidelines may be followed to reduce the effects
of RF noise:
a.
Use additional appropriate AC radio frequency interference (RFI)
power line filter rated for minimum 10 A immediately before the AC
input of the power supply. For example, consider suitability of
model # 10VN1 from "N" series by Corcom, Inc. (www.cor.com) or
similar. Filtered, ferrite coated cord set (www.emceupen.com ) is
another choice. These cord sets, with integral line interference
filters, reduce common and differential mode interferences over a
wide frequency range. Because they are shielded, they are also
effective against radiated interferences. In addition to the built-in
filter networks, the cable conductors are coated with an RF
absorbing ferrite compound. This provides additional attenuation
at high frequencies that is lacking in most regular LC filters. The
RF absorption of the ferrite-coated cable avoids resonances at
high frequencies, reducing the conducted and radiated RF noises
even further
b.
Use additional appropriate DC radio frequency interference (RFI)
power line filter rated for minimum 40 A immediately after the DC
output of the power supply. For example, consider suitability of
model # "FD10B050" from "FD" series by Curtis Industries
(www.curtisind.com) or similar.
c.
Twist the positive and negative wires from the output of the power
supply to the radio
d.
The DC side positive and negative outputs of these power sup-
plies are isolated from the chassis. As explained at paragraph 6
above, the noise currents are filtered to the chassis ground and
the chassis ground is connected to the earth ground through the
earth ground pin of the AC power outlet receptacle. Avoid connect-
ing (referencing) the DC negative output terminal of the power
supply to the earth ground.
e.
Connect a 1/4" wave length of wire on the negative terminal of the
power supply. Connect one end of the wire to the negatvie terminal
and leave the other end free. The wave length corresponds to the
wave length of the interfering frequency. (May not be practical for
long wave lengths)
[ Formula: Wave length (Meters) = 300 / frequency in MHz ]
10.
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