Bird Technologies 8890-400 Series - Manuale (Pagina 36)

Coolant
The level of the dielectric coolant should remain constant in
the unit even after prolonged usage under normal operating
conditions. Inspect occasionally around the lower portion of
the clamping band, for possible coolant leakage. Tighten the
clamping screw if required. Under very unusual conditions
it might become necessary to replace the resistor housing
seal O-Ring.
CAUTION
This unit is factory filled with approximately 2.9
gallons (11 liter) of a specially selected dielectric fluid,
P/N 5-1070-3. No other coolant should be used.
Check the coolant level by placing the load on end with the
input connector up. As above, remove the load resistor as-
sembly. When the unit is at ambient room temperature, the
coolant level should be 4-3/4 inch (120 mm) below the top
surface of the load resistor assembly mounting ring.
When the coolant oil is heated, thermal expansion will
cause an increase in the internal pressure. The vent plug in-
stalled on the topside of the radiator tank is provided to re-
lieve this pressure while protecting the opening from
possible entry of dirt or other contamination.
RF Input Connector
The input connector on the 8890-400, is of a special “QC” de-
sign which permits easy interchange of connectors using
only a screwdriver. This process does not in any way disturb
the coolant seal or interfere with the essential coaxial conti-
nuity of the load resistor input. Normally, a Female LC con-
nector is supplied with the Series 8890-400. However, other
“QC” connectors may be used.
It must be clearly understood that at the full power and fre-
quency capability of this model, refer to the specification,
only type LC or LT (Female or Male) or 7/8 inch EIA air line
connectors will be adequate. Even though connectors are
easily changed, as described below, for any of the other con-
nector types listed herein, input power values must be lim-
ited to the specified parameters of the selected type.
26
Bird Model 8890-400 Series Termaline Wattmeter