TB 9-6625-2235-24
15. Residual FM Test
a. Performance Check
(1) Position controls as listed in (a) through (e) below:
(a) FREQ SPAN/DIV switch to 100 kHz.
(b) RESOLUTION BW switch to 10 kHz.
(c) INPUT ATTEN switch to 0 dB (OPTIMUM INPUT switch to -40 dBm).
(d) REFERENCE LEVEL switch to -20 dBm.
(e) Press LIN pushbutton in.
(2) Connect comb generator output to INPUT 50Ω.
NOTE
Increase INPUT ATTEN switch setting if comb generator
signal amplitude overdrives crt indication.
(3) Adjust TUNING control to center 500 MHz signal on crt and press
FREQUENCY CAL pushbutton.
(4) Position signal peak at top crt horizontal line (fig. 15) with REFERENCE
LEVEL switch and REF LEVEL FINE control.
(5) Maintain signal center on crt with TUNING control while reducing FREQ
SPAN/ DIV switch to 0.
(6) Set RESOLUTION BW switch to 10 kHz and SWEEP TIME/DIV switch to .1s.
(7) Slightly adjust TUNING FINE control until trace appears between 4th and 7th
vertical graticule from graticule baseline. Peak-to-peak variation of trace will not exceed
one major vertical division for each major horizontal division.
b. Adjustments. No adjustments can be made.