Replacing the resistor, Replacing fractured resistors – Bird Technologies 8740 Series User Manual
Page 24
Maintenance
14
Replacing the Resistor
1. Inspect the load housing assembly. See “Inspecting the Unit” on page 13.
2. Insert new resistor [1] into the load housing until it reaches its fitting.
3. Push in the resistor until it bottoms snugly.
Note:
If resistor seems to be loose, see “Replacing Fractured Resis-
tors” on page 14 for instructions on how to lighten the resistor fitting.
4. Place the inner flow tube [9] inside the resistor.
5. Lower the inner flow tube until it reaches the resistor fitting.
6. Gently work and twist the inner flow tube until it seats in the bottom of
the input resistor fitting.
Note:
This operation may also be done if the inner flow tube is still
in position in the water chamber.
7. Ensure that the O-Ring [8] cushion is placed on the inner flow tube next to
the resistor and the “backup” resistor sleeve [7] is right behind it.
Note:
Watch the orientation of the sleeve, see “Replacing a Resis-
Note:
There is no need to disturb the resistor cap assembly [10] in
the water chamber for this procedure.
8. Replace the water chamber [3], gently rocking and twisting the chamber
to achieve the proper flat seat on the outer housing.
Note:
If the water chamber [3] does not seem to fit properly, refer
back to step 5. to see that the inner flow tube is properly in place.
9. Tighten the six 1/4-20 x 2-112 inch socket head cap screws [6].
10. Check the DC resistance between the inner and outer conductors.
Note:
It should be approximately 50 ohms, see “Inspecting the Unit”
11. Connect the load to a water source and check for leaks.
Note:
If none appear, the load is ready for service.
Replacing Fractured Resistors
Note:
The load should already be disassembled to the point of step
4 of "Replacing a Resistive Element" on page 11.
1. Turn the load on end.
Note:
The RF input connector should be up to allow any loose
pieces of resistor to fall out of the load housing.
WARNING
The resistor used in this load consists of a resistive film on a special
substrate. If the substrate is broken, there will probably be sharp pieces or
splinters inside the load housing. Caution should be exercised to avoid
possible injury.