4. IF Amplitude Adjustments

A5 IF

A 4 L O G A M P

 

J9

 

J 7

 

R 8 2 6

R 4 4 5

J2

 

38

JIO

J 5

( R E V I S I O N C O N N E C T O R )

Jl

Jll

J 4

R 5 4 4

J 4 ’ /

J 3

R 5 3 1 '

SK190

Figure 2-7. IF Amplitude Adjustment Locations

A4 Log Amp/Cal Oscillator Amplitude Adjustment

This adjustment sets the output amplitude of the A4 Log Amp/Cal Oscillator and the absolute amplitude of the reference 15 dB attenuator.

The output of the A4 Log Amp/Cal Oscillator is adjusted so that a -55 dBm signal applied to the 10.7 MHz IF input on the A5 IF assembly (A5J3) causes a displayed signal of -60 dBm. The effect of this adjustment is visible only after the ADJ CURR IF STATE

sequence is complete. ADJ CURR IF STATE causes the IF gain adjustment to use the “new” output amplitude from the A4 Log Amp/Cal Oscillator. When the adjustment sequence

is complete, the result of the adjustment should cause the -35 dBm signal at A5J5 to be displayed at -60 dBm.

This procedure also sets the attenuator of the reference 15 dB attenuator so that a source amplitude change of 50 dB combined with a spectrum analyzer reference level change of 50 dB displays an amplitude difference of 50 dB.

Note

The 15 dB Reference Attenuator adjustment is preset at the factory and need

 

not be done if the entire A5 IF assembly is replaced.

 

 

2-26 Adjustment Procedures