First Local Oscillator Adjustment (cont'd)

Section V

TM 11-6625-2781-14&P-2

ADJUSTMENT PROCEDURES (cont'd)

5-22. First Local Oscillator Adjustment (cont'd)

ANALYZER Control Settings (cont'd)

BASE LINE CLIPPER ................................ ................................ ................................ ................................ ......... ccw

SCAN TIME PER DIVISION ................................ ................................ ................................ ........ 2 MILLISECONDS

LOG REF LEVEL ................................ ................................ ................................ ................................ ......... -10 dBm

LOG REF LEVEL Vernier................................ ................................ ................................ ................................ .... ccw

LOG-LINEAR ................................ ................................ ................................ ................................ ..................... LOG

VIDEO FILTER ................................ ................................ ................................ ................................ .................. OFF

SCAN MODE ................................ ................................ ................................ ................................ ....................... INT

SCAN TRIGGER ................................ ................................ ................................ ................................ ............ AUTO

8406A:

COMB FREQUENCY - MC ................................ ................................ ................................ ............................. 10 MC

INTERPOLATION AMPLITUDE................................ ................................ ................................ ......................... OFF

OUTPUT AMPLITUDE................................ ................................ ................................ ................................ .3 o'clock

5245L/5252A:

SAMPLE RATE................................ ................................ ................................ ................................ ............ 8 o'clock

SENSITIVITY................................ ................................ ................................ ................................ .............. PLUG IN

TIME BASE ................................ ................................ ................................ ................................ ..................... 10 ms

FUNCTION ................................ ................................ ................................ ................................ ......... FREQUENCY

MAX COUNT RATE................................ ................................ ................................ ................................ .... 350 MHz

2. Center dial pointer on 0 MHz using FREQUENCY control.

3. Select ZERO SCAN WIDTH, and center TUNING RANGE Adjust A5A1R13.

4. Adjust A7A1R3 LOW FREQ ADJ in the 8553B for maximum base line lift. (In ZERO SCAN WIDTH base line lift

is an indication that signals are present.)

5. Turn FREQUENCY to 110 MHz. The counter should read 310 MHz ± 10 MHz.

300

320 MHz

6. Turn SCAN WIDTH to PER DIVISION. Turn

FREQUENCY to 5 MHz. The local oscillator

feedthrough signal should appear on the left

edge of the graticule.

7. Tune FREQUENCY until half the feedthrough

signal appears at the left edge of the graticule.

See Figure 5-2.

8. Adjust A5A1R32 until half the comb signal

appears at the right edge of the graticule.

Readjust FINE TUNE and A5A1R32 as

necessary until half of each signal appears on

the edges of the graticule.

9. Select ZERO SCAN WIDTH. Measure the first

local oscillator frequency. The frequency should

be 205 ±0.5 MHz.

Figure 5-2. First Local Oscillator Adjustment: CRT

Display

10. Select SCAN WIDTH PER DIVISION. Change the comb generator COMB FREQUENCY MC to 1 MC.

11. The comb spectrum should be evenly distributed across the graticule. The center comb should be on the center

graticule ± 0.3 divisions (300 kHz).

12. Return the comb generator to the 10-MC comb.

5-6