Table of Contents
Advertisement
FM Tracking
1. Turn the MUTING
and MPX FILTER switches
to the OFF position, tum the IF BAND switch
to the NARROW
position, and the FUNCTION
switch to the FM position.
. Set up the test equipment as Fig. 7-4.
. Connect the wire between Tuner ass'y terminal
26 and ground.
4. Connect a DC voltmeter between
Tuner ass'y
terminal 43(+) and ground(—).
5. Adjust the VR;
of the APC
ass'y to obtain a
reading of +8V on the DC voltmeter (refer to
Fig. 7-2).
6. Disconnect the DC voltmeter from the Tuner
ass'y.
7. Set
the
FM
signal
generator
(FM
SG) to a
modulation
frequency
of
400Hz,
FM
devia-
tion of 75kHz,
and output level of 60dB to
8OdB.
8. Set the FM SG output frequency and the dial
frequency of the TX-9800 to 90MHz.
9. Adjust the core of Ly) to obtain
a maximum
reading on the SIGNAL meter.
10. Set
the
FM
SG
output
frequency
and
dial
frequency of the TX-9800 to 106MHz.
11. Adjust the TC, to obtain
a maximum
reading
on the SIGNAL meter.
12. Adjust by repeating steps 8 to 11.
13. Set output level of the FM SG from 20dB to
30dB.
14. Set
the
FM
SG
output
frequency
and
dial
frequency of the TX-9800 to 90MHz.
15. Adjust the gap of coils (L3; to L,)* and core of
L, and T, to T; to obtain
a maximum reading
on the signal meter.
16. Set
the
FM
SG
output
frequency
and
dial
frequency of the TX-9800 to 106MHz.
17. Adjust TC, to TC, to obtain a maximum read-
ing on the SIGNAL meter.
18. Adjust by repeating steps 14 to 17.
19. Connect the wire between Tuner ass'y terminal
37 and ground.
20. Turn
the dial frequency
of the TX-9800
to
98MHz without any input signal.
21. 'Adjust the core of T,-a so that the TUNING
.meter reads dead center.
22. Turn
the IF BAND
switch to the WIDE posi-
tion.
23.Set
the
FM
SG
output
frequency
and
dial
frequency
of the TX-9800
to 98MHz.
Then
TUNING meter reads dead center.
24. Set output level of the FM SG to 60dB.
25. Adjust
the
core
of T,-b
to reduce
distortion
in the output to a minimum.
26. Repeat steps 20 to 25 above so that the TUN-
ING
meter reads dead center with a minimum
wb
16
of distortion.
27. Disconnect wire between Tuner ass'y terminal
26 and ground.
28. Adjust the TC, of the APC
ass'y so that the
TUNING meter reads dead center.
29. Disconnect the wire between
Tuner ass'y ter-
minal 37 and ground.
30. Set the FM
SG
output frequency
and dial
frequency of the TX-9800 to 98MHz.
31. Set the FM SG output level to 100dB, and then
adjust VR;
so that the SIGNAL
meter reads
4.8 on the scale.
32. Set the
FM
SG
output
level
to 35dB,
and
record
the
deflection
level
of the
SIGNAL
meter.
33. Turn
the IF BAND
switch to the NARROW
position.
34. Adjust VR, to obtain the same deflection level
of the SIGNAL
meter as the deflection level
recorded in step 32.
35. Turn the IF BAND
switch to the WIDE
posi-
tion.
36. Turn the MUTING switch to the ON position.
387. Set the FM SG output level to 20dB, and then
adjust
VR,
to the
point
where
the muting
operated.
Multiplex Decoder
38. Connect the multiplex signal generator (MPX
SG)
to the external
modulator
terminals
of
FM
SG,
thereby
using
FM
SG
as
external
modulation.
39. Connect
the frequency
counter
between
ter-
minal 17 of the Tuner ass'y and ground.
40. Turn the MUTING
switch to the ON position
and IF BAND switch to the WIDE position.
41. Set the FM
SG output frequency
to 98MHz,
and output level to 60dB, unmodulated.
42. Tune the TX-9800 to check that the SIGNAL
meter
gives
maximum
deflection,
and
the
TUNING
meter reads dead center.
43. Adjust VR;
to obtain a reading of 76kHz on
the frequency counter.
44. Disconnect the frequency counter.
45. Set the MPX
SG modulation
output to pilot
signal (19kHz) only, and set the FM deviation
to 7.5kHz.
46. Adjust
VR,
so that the AC voltmeter
(OUT-
PUT) shows minimum reading (19kHz leak).
47. Set the MPX SG to 1kHz
(Lor R) 33.75kHz
deviation
and
19kHz
(pilot signal)
7.5kHz
deviation.
48. Adjust the core of T, (less than +90°) for
minimum distortion at the L or R output.
49. Turn the IF BAND
switch to the NARROW
position.
Advertisement
Table of Contents
