Fig. 4-16. Removing the phase-lock assembly board.

3. Band C Mixer Diodes

1. Band A Mixer Diodes

a. Coaxial Mixer. Unscrew the base of the coaxial mixer.

a. Disconnect the sub-miniature connectors, remove the

Fig. 4-18C. Replace the diode and re-assemble the mixer.

two mounting screws and the mixer assembly.

b. Waveguide Mixers. Unscrew the cap over diode and

CAUTION

replace the-diode. See Fig. 4-18D.

Do not tip or bend the connectors in removing

them. Grasp the body of the connector with the

Oscillator Tube Replacement

fingers or needle nose pliers at the base of the

connector, and pull straight out.

NOTE

A complete oscillator assembly and its sub parts

b. Remove the four screws and spacers that hold the

are listed in the Mechanical Parts section. Replac-

cover and circuit plate to the shell.

ing components such as the oscillator tubes requires

c. Unsolder and replace the diodes with a matched pair.

a complete recalibration with special test equip-

ment and technique. We therefore recommend

See Fig. 4-18A. USE A HEAT SINK WHEN SOLDERING

THE NEW DIODES INTO PLACE, SEE SOLDERING TECH-

replacing the complete assembly and returning the

NIQUE.

defective assembly to your Tektronix Field office

or representative. A calibration procedure is pro-

e. Replace the cover and the mixer assembly. Reconnect

vided in the Calibration section, if it is impractical

the connectors to the mixer assembly.

to return the assembly for repair.

The oscillator tube should only be replace after all tests

2. Band B Mixer Diode

indicate the tube is faulty. Check supply voltages, etc., as

a. Remove the front panel mounting nut and washer.

illustrated in Fig. 4-19A.

b. Slip the mixer assembly back and out of the unit.

1. Band A and B oscillator tube replacement (V40 and V41)

a. Unscrew and remove the screws that hold the tap plate

c. Unscrew the front barrel (1 dB pad) and replace the

to the oscillator chamber. Remove the top plate.

mixer diode. See Fig. 4-18B.

4-13