off. If the interference does not stop when the
frequency stabilized welder installation may cause
interference over a wider area.
welder is turned off, obviously the welder is not
causing the interference.
(6) There are many electrical devices which
Note. The amount of radiation from any installa-
can cause radiation and, in most cases, it is easy to
tion can be very greatly reduced if the installation is prop-
distinguish between the radiation from these de-
erly made. Factors such as the proper grounding of the
vices and that coming from a high frequency sta-
welding equipment and the shielding of exposed wires enter
bilized welder installation. However, it has been
into making a good installation.
found that there are some electrical devices which
(7) Installation of High Frequency Stabi-
are capable of causing radio interference and
lized: Arc Welders and related equipment should
which, in a radio receiver, are almost identical
be made in accordance with instructions in this
with the interference caused by a welder. There-
manual.
fore, in all cases where there is a complaint, a
e. General Instructions for all Installations.
quick check should be made to determine if the
i n t e r f e r e n c e is actually being caused by the
(1) The following steps should be taken on all
welder. The easiest way to do this is to listen in on
installations. This procedure will substantially
the radio receiver in which interference is occur-
reduce the radiation, and the installation will be
ring while the welder is being turned on and off.
less likely to cause radio interference than an in-
Where more than one welder is being used, each
stallation made in a haphazard manner. The wider
should be tested individually with the other turned
the spark gap setting, the greater is the power
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