Replacing the resistor – Bird Technologies 8650B Series User Manual

Page 36

Bird 8650 Series Moduload RF Load Resistor

Replacing the Resistor

Note:

Use this section only if there has been no damage done to the

resistors or other internal parts of the load.

1. Insert the new resistor into the load housing until it reaches the resistor

fitting.

2. Rotate, and rock, carefully, the resistor until it starts to enter its way into

the resistor fitting.

3. Push the resistor into the fitting until it bottoms on the spacer ring.
4. Ensure the spacer ring is in the proper place.

Note:

If the resistor seems to be loose, refer to the procedure for the

replacement of fractured resistors or damaged internal parts. That sec-

tion has instructions on how to tighten the resistor fitting.

5. Do one of the following:

If damaged:
a. Replace the inner flow tube.

If undamaged:
a. Place the original flow tube inside the resistor.
b. Lower it until it reaches the resistor fitting.
c. Gently work and twist the inner flow tube until it seats in the bot-

tom of the resistor fitting.

Note:

This operation may also be done if the inner flow tube is

still in position in the water chamber when the main housing is

being reinstalled.

6. Slide the back-up resistor sleeve and O-Ring down the inner flow tube

until it rests on the end of the resistor.

Note:

There is no need to disturb the resistor cap assembly in the

water chamber for this procedure. If the ground cap has been removed,

replace it on the end of the resistor before continuing.

7. Install the water chamber gently rocking and twisting the chamber to

achieve the proper flat seat on the outer housing.

Note:

If the water chamber does not seem to fit properly, refer back

to step 3 to make sure the inner flow tube is properly in place.

8. Place the resistor housing through the front panel opening, and into the

water chamber.

9. Turn the housing, gently, clockwise to thread it on, eventually bottoming

it in its original position.

10. Reverse "Removing the RF Load" on page 19.

Note:

Do not replace the top panel until after this section is com-

pleted.

11. Check the DC resistance between the outer and inner conductors; it

should be approximately 50 ohms. See “Measuring DC Resistance” on

page 16, and Figure 10 on page 16.

12. If the resistance check passes, flush out. See “Flushing the System” on page 18.
13. Inspect for leaks by running the coolant pump for a few minutes without the

top panel.

Note:

After the completion of this or any of the resistor repair pro-

cedures, run the pump/motor for five minutes and check thoroughly for

leaks before applying RF power to the load.

14. Install the top panel.