Inspecting The Resistor; Removing A Fractured Resistor; Replacing The Resistor - BIRD Moduload 8640 Series Operation Manual

Moduload® RF Load Resistor
The resistor sleeve [7] has a small escape hole at the side and an access counter bore leading to it. If the sleeve is
removed, be sure this counterbore faces the O-Ring and the resistor [1] during reassembly. This is essential for
internal water venting. The base of the inner flow tube has water outlet holes and a small shoulder. At reassembly,
these must fit into mating recesses in the input fitting.

Inspecting the Resistor

Note: Carefully check the resistor [1] for fractures.
Note: Even in the event of resistor failure the resistor substrate will usually remain intact.
Check the inside of the load housing for damage to the internal parts.
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If no damage has been found proceed to "
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If the resistor is broken, other internal parts are damaged, or if the parts do not fit together properly,
proceed to "

Removing a Fractured Resistor

Removing a Fractured Resistor
1. Turn the load on end with the RF input connector up to allow any loose pieces of the resistor to fall out of the
housing.
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2. Use a hex socket wrench to remove the cap screws [16].
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3. Remove the outer conductor assembly [12].
4. Pull out the center conductor assembly [11].
5. Remove any remaining pieces of the resistor carefully.
Note: Normally the outer flow tube will remain with the load housing. If it comes out, return it after
inspection and cleaning.
6. Check the inside of the load housing for damage.
7. Remove the inner flow tube [9] and ground cap assembly [10].
Note: Check them for broken pieces.
8. Under clear running water, thoroughly wash the inside of the conductor assemblies, load housing, and water
chamber.
9. Replace the ground cap assembly and the inner flow tube.

Replacing the Resistor

1. Insert the new resistor [1] into the resistor fitting of the center conductor assembly [15] to test its tightness.
Note: The resistor should be snug but should not have to be forced into the fitting. If the resistor is too
loose, press the fitting fingers together slightly and try the resistor again. Continue closing the ends of
the resistor fitting until a snug fit is obtained.
2. Bottom the resistor in the fitting.
3. Insert the resistor and the center conductor assembly into the load housing.
4. Replace the outer conductor assembly [12] and screw it into place.
5. Stand the load on its end with the RF connector down.
6. Replace the ground cap assembly onto the exposed end of the resistor. Make sure that it seats on the load
housing.
Note: If the inner flow tube [9] is separated from the water chamber assembly [3], place it inside the
resistor and lower until it reaches the resistor fitting. Gently twist the flow tube until it seats in the bot-
tom of the resistor fitting.
7. Check that the O-Ring [8] is on the inner flow tube next to the resistor and the resistor sleeve [7] is right behind
it.
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".
Replacing the Resistor
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