19. Second Converter Adjustments

9.Readjust A23A3 2ND MIXER A23A3Z4 for maximum power indication.

10.Disconnect the amplifier’s input from A23A3J3 and connect to A23A3J4.

11.Adjust A23A3 PILOT 2ND MIXER A23A3Z8 for maximum power meter indication. See Figure 3-73 for location of adjustment.

12.Disconnect power meter and connect frequency counter to amplifier’s output.

13.Key in [SHIFT) @) u to shift Second LO up and ISHIFT) a T to shift Second LO down.

14.Continue to shift Second LO up and down while adjusting A23A3 2ND LO SHIFT A23A3ZlO for a frequency difference of 5.0 MHz fO.l MHz. Ignore the absolute value of either frequency. Clockwise rotation of A23A3ZlO decreases the frequency difference.

15.Key in (SHIFT) a T (Second LO shifted down).

16.Adjust A23A3 2ND LO FREQ A23A3Z9 for frequency counter indication of 1748.6 MHz fO.l MHz.

17.Repeat steps 13 through 16 until specifications of steps 14 and 16 are achieved.

18.Disconnect frequency counter and connect power meter to the amplifier’s output.

19.Shift Second LO up and down, using m m u and (SHIFT) a T while adjusting A23A3 PILOT 2ND MIXER A23A3Z8 for equal power out in both states of Second LO.

20.Power difference between Second LO shifted up and shifted down should be less than 0.5 dB.

21.Disconnect amplifier’s input from A23A3J4 and connect to A23A3J3.

22.Shift Second LO up and down, using (SHIFTY a u and ISHIFT) @) T while adjusting A23A3 2ND MIXER A23A3Z4 for equal power out in both states of the Second LO.

23.Power differences between Second LO shifted up and shifted down should be less than 0.5 dB.

24.Disconnect power meter and connect frequency counter to amplifier’s output.

25.Key in [SHIFT) a T. Note frequency counter indication. If necessary, readjust A23A3 2ND LO FREQ A23A3Z9 for frequency counter indication of 1748.6 fO.l MHz.

26.Shift Second LO up and down, using ISHIFT) @) ’ and ISHIFT) a

T and note frequency difference between low and high state of Second LO. If necessary, readjust A23A3 2ND LO SHIFT A23A3ZlO for a frequency difference of 5.0 MHz fO.l. Repeat steps 27 and 28 until specifications contained in each step are achieved.

Adjustments 3-125