20. 50 MHz Voltage-Tuned Oscillator Adjustments
VT0 High-Frequency End AdjustmentVT0 Low-Frequency End AdjustmentVT0Center-FrequencyChecks

14.Adjust All POS SUPPLY AllR6 for a DVM indication the same as that noted in step 12. See Figure 3-79 for location of adjustment.

15.Key in LSHIFT) (CF STEP SIZE] J 112 kHz and Cm) I-1 N.

16.Adjust All OFFSET AllRlO for VTP frequency indication 28.000 MHz f0.005 MHz.

17.Key in ISHIFT) [CF STEP SIZE) J 12 kHz and [SHIFT) I-1 N.

18.Adjust All GAIN AllR9 for VT0 frequency indication of 28.750 MHz fO.005 MHz.

19.Repeat steps 15 through 18 until specifications of steps 16 and 18 are achieved.

20.Key in ISHIFT) [CF STEP SIZE] J 912 kHz (m) [wCF_) N.

21.Adjust All SHAPING ATTN AllR42 for VT0 indication of 22.000

MHz f0.005 MHz. See Figure 3-78 for location of adjustment.

22.Key in (Ml (CF STEP SIZE) J 1012 kHz and [SH’FT) [NII(R) N.

23.Adjust All SHAPING OFFSET AllR17 for VT0 frequency indication of 21.250 MHz *0.005 MHz. See Figure 3-78 for location of adjustment.

24.Repeat steps 21 through 23 until specifications of steps 20 and 23 are achieved.

25.Go back to step 15 and repeat both High-Frequency End and Lo-Frequency End adjustments until specifications of both (contained in steps 16, 18, 21, and 23 are achieved.

26.Key in ($KEj [CF STEP SIZE) J 512 kHz and Cm) [m) N.

27.VT0 frequency indication should be 25.00 MHz f0.02 MHz. If it is not, and specifications of steps 16, 18, 21, and 23 are met, a malfunction is indicated. The most likely suspects would be varactor diodes CR15 and CR16.

28.Key in ISHIFT_) [CF STEP SIZE] J 612 kHz and cm] I-1 N.

29.VT0 frequency indication should be 24.25 MHz kO.02 MHz. If it is not, and specifications of steps 16, 18, 21, and 23 are met, a malfunction is indicated. The most likely suspects would be varactor diodes CR15 and CR16.

30.Set LINE switch to STANDBY.

31.Replace Al1 50 MHz Voltage-Tuned Oscillator in instrument without extenders and replace screws in cover.

3-132 Adjustments