[R-390] R390 power cord

[Roy Morgan]

At 06:14 PM 4/22/2005, Dan Merz wrote:
>... I'm in the habit of acquiring
>the pc-type power cords and cutting the female end off

Dan,

Good plan.

>... First question:  is this wire size big enough?

Yes.

>...Second question:  Should I connect both the covered green wire
>and the uncovered wire to the radio ground at the radio?

Yes.

>...  I assume the
>purpose of the uncovered ground wire has to do with contact to the metal
>sheathing (shield) around all the wires.  Dan.

Yes. It's called a drain wire, and is the best way to make contact with the 
foil shield. You may notice that the jacket markings include the word 
"Shielded".  Only some computer type cords have this, and the ones that do 
seem to be thicker than the ones that don't.  I use them on receivers, even 
if the receiver has line bypass caps installed (or a line filter as the 
R-39x radios do.)

I was poking through a box of such cords recently, and it's my impression 
that cords can be grouped by thickness as follows:

18/3 no shield
18/3 with shield
16/3 no shield
16/3 with shield

Please check with an ohmmeter the line and neutral connections.   Note: the 
LINE connection in an outlet is narrow.  The Neutral connection is wide. 
The Safety ground connection is round.  (In a three wire line cord, the 
flat blades may both be narrow.  In a "Polarized" two-wire line cord, one 
is wide.

Here's color code information from a message by Bob Nickels

"...For years, the colors of individual conductors in cords for use in 
North America have been black for line, white for neutral, and green for 
earth (ground).
But in order to harmonize worldwide standards,  two major UL equipment
standards, UL 1950, Information Technology Equipment, and UL 2601, Medical
and Dental Equipment, started several years ago to require the more
traditional European conductor color coding: brown for line, light blue for
neutral, and a  combination of green and yellow for ground.

The color conversion is as follows:

LINE            (US) Black  =  (EU)  Brown
COMMON   (US)White  =  (EU)  Blue
GROUND    (US) Green     (EU)  Green/Yellow ..."

As you replace normal line bypass capacitors, do not put them back one each 
from line and neutral to chassis, put them as follows:

One from Line to Neutral
One from Neutral to chassis.

Complete, longer diatribe on line cords and bypassing supplied separately 
to anyone who requests it.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Cell 301-928-7794
Work: Voice: 301-975-3254,  Fax: 301-948-6213
roy.morgan at nist.gov --