8. 21.4 MHz Bandwidth Filter Adjustments

Equipment Digital Voltmeter (DVM) . . . . . . . . . . . . . . . . . . . . . . . .HP 3456A

10dB Step Attenuator . . . . . . . . . . . . . . HP 355D, Option H89

1dB Step Attenuator . . . . . . . . . . . . . . . HP 355C, Option H25 Crystal Filter Bypass Network (2 required) . . . . Refer to Figure 3-91

Procedure 1. Position instrument upright as shown in Figure 3-40 and remove top cover.

2.Set LINE switch to ON and press QNSTR PRESET].

+10 V Temperature Compensation Supply Check

3.Connect DVM to A4A5TPl (+ 10 VF).

4.DVM indication should be between +9.0 V dc and + 10.0 V dc. If voltage is within tolerance, proceed to next step. If voltage is not within tolerance, refer to Adjustment 10, Step Gain and 18.4 MHz Local Oscillator Adjustments, for adjustment procedure.

A4A4 LC Adjustments

5.Set step attenuators to 0 dB.

6.Disconnect cable 97 (white/violet) from A4A8Jl and connect to A4A6J 1.

7.Key in CCENTER FREQ] 20 MHz, (jREs] 100 kHz, [FREQUENCY SPAN) 200 kHz, and press LIN pushbutton.

8.Press (REFERENCE LEVEL) and adjust front-panel knob to set signal peak on screen two divisions from the top graticule.

9.Adjust A4A4C67 LC CTR and A4A4C19 LC CTR for maximum MARKER level as indicated by CRT annotation. See Figure 3-41 for location of adjustments. If unable to adjust LC CTR adjustments for satisfactory signal amplitude, increase or decrease value of A4A4C17 and A4A4C70. Refer to Table 3-3 for range of values.

A4A4

Bnndwdth Filte

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c

uA4A4

Figure 3-41.

Location of A4A4 21.4 MHz LC Filter Adjustments

3-78 Adjustments