Frequency Deviation For A Radiotelephone - Furuno FM-8800D Service Manual

6.2.5 Frequency deviation for a radiotelephone

Connect FM Liner Detector as below. Connect AF OSC (AF Oscillator) and an
appropriate switch as a substitution to PTT switch.
HANDSET
AF OSC
600 ohm
PTT SW
Fig. 6.2.5 Measurement of Frequency Deviation
Procedure
1. Set up the frequency for AF OSC to 1 kHz. Modulation frequency: 1 kHz.
2. Turn on PTT switch.
3. Adjust the output level of AF OSC (Adjust the modulation level.) so that it may be set
up to Frequency Deviation: 3.5 kHz.
4. Measure the Frequency Deviation when the modulation level is increased +20 dB
from the above-mentioned AF OSC level.
Frequency Deviation is regulated to be within 5 kHz.
NOTE:
Modulation Index (m) =
ANT
FM-8800S
FM-8800D
3-4
CH70 ANT
1-2
Frequency deviation
Modulation
6-8
50 ohm ATT
(20dB)
Pick-up
(kHz)
frequency (kHz)
6.2 Measurement
50 ohm
Dummy
FM Liner
Detector