Al4 Frequency Control Assembly

Note

The block

diagrams for the Al4 and Al5 assemblies are located in Chapter 10,

 

Synthesizer

Section.

 

 

 

A7 LODA Drive

See function block Z of Al4 Frequency Control Schematic Diagram (sheet 3 of 5) in the Component-Level Information binder.

1. Set the HP 8560A to the following settings:

CENTER FREQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300 MHz

SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2 MHz

TRIGGER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..SINGLE

2.Measure the signal power at the output of A7 (see item (1) of Figure 11-2).

3.If the output power is low, A14U424A’s output voltage, item (a), (A14J18 pin 14) should be above 0 V. If the output power is high, the voltage should be more negative than

-10 V. If the voltages do not measure as indicated, check that the voltages at A14J18 pins 5 and 13, item (4), are consistent with the operational amplifier’s output.

Note

If a TAM is available, use Manual Probe Troubleshooting to make

 

measurements on A14J18 pins 5, 13, and 14. These voltages are referred to as

 

. AMP CNTL, LO SENSE, and PIN ATTEN respectively.

 

 

4.If the voltages measure as indicated in step 3, measure the All YTO output. (See item (3) of Figure 11-2.)

5.If all measurements are within limits, refer to “A7 LODA (LO Distribution Amplifier)” in this chapter.

RF Section 1 l-9