10. Step Gain and 18.4 MHz Local Oscillator Adjustments

A4A5 S T E P G A I N

R2

 

Cl0 F R E O

R51

+lOV A D J

RlO

Z E R O C O A R S E C9

“ R

A4A5

Figure 3-49.

Location of .l dB Gain Step, 18.4 MHz LO, and + 1OV

Adjustments

36. Key in [FREQUENCY SPAN] 1kHz, [REs] 100 Hz, and

[PEAK SEARCH] a].

37.Adjust front-panel FREQ ZERO control fully clockwise. Press CPEAK SEARCH]. Signal should move at least 60 Hz away from center CRT graticule line.

38.Adjust front-panel FREQ ZERO control fully counterclockwise. Press [PEAK XEARCH]. Signal should move at least 60 Hz away from center CRT graticule line.

39.If proper indications are not achieved, increase or decrease value of A4A5C9 and repeat adjustment from step 33. Refer to Table 3-3 for range of values.

40.Press [INSTR PRESET) and IRECALL) @.

41.Adjust front panel FREQ ZERO to peak the signal trace on the CRT.

+ 1OV Temperature Compensation Supply Adjustment

42.Connect DVM to A4A5TPl (+ 1OVF).

43.If DVM indication is between +9 V dc and 10.0 V dc, no adjustment is required.

44.If DVM indication is not within tolerance of step 43, adjust A4A5R2 + 1OV ADJ for DVM indication of +9.5 ItO. V dc at normal room temperature of approximately 25°C. Voltage change is approximately 30 mV/OC. Therefore, if room temperature is higher or lower than 25OC, adjustment should be made higher or lower, accordingly.

Adjustments 3-91