Bird Technologies 8890-400 Series - Manuale (Pagina 28)

Start-Up Proceed according to the instructions pertaining to the spe-
cific transmitting equipment. Due to the difference in
VSWR between the dummy load and the transmitter’s an-
tenna, readjustment of the transmitter may be required
when returning to the original antenna.
WARNING
Never attempt to disconnect RF equipment from the
transmission line while RF power is being applied.
Leaking RF energy is a potential health hazard.
Normal
Operation
Since there are no operating controls or adjustments, these
wattmeters do not require hands-on attention. They should
function faultlessly converting RF energy into heat for in-
definite periods providing their power capacity is not ex-
ceeded.
To make measurements:
1. Insert the appropriate element in the socket of
the line section. Rotate the element so that the
arrow on the nameplate is pointed away from
the RF source for forward power and towards
the source for reflected power.
2. Turn on the RF source and read the power
level from the appropriate meter scale.
Operation
Under
Abnormal
Conditions
Series 8890-400 Wattmeters are not intended or recom-
mended for outdoor use where they may be unprotected and
exposed to the elements. They may be subjected to moderate
overloads for limited periods without overheating. However,
this should be done cautiously and it is strongly recom-
mended that if such a use is contemplated, the load be
equipped with a thermoswitch, P/N 8890-008. When inter-
locked with the power line of the RF source, the ther-
moswitch becomes a fail safe device to guard the load
against the danger of overheating.
Shutdown Because these wattmeters are passive devices and require
no external source of power, they can not be shut off. The
RF source must be turned off instead. On blower equipped
models, the blower fans will turn off automatically as the
wattmeter cools.
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Bird Model 8890-400 Series Termaline Wattmeter