12 dB SINAD and Distortion Tests
1. Connect the distortion analyzer or SINAD meter to the
speaker load (in Dummy Battery).
2. With the RF signal generator and radio set to 860.5125
MHz, modulate the generator with a 1 kHz tone at ±3
kHz deviation. Measure the 12 dB SINAD sensitivity.
This reading should be equal to or better than -116 dBm
(0.35 µV).
3. Return the signal level to -50 dBm.
4. Checkaudiodistortion.Readingsshouldbeless than5%
at rated audio output. Audio amplitude should be 100 -
150 mV rms (≈350 mVp-p) at J101/P1 pin 4.
5. Repeat the 12 dB SINAD sensitivity and distortion
check for the LOW and HIGH-side test channels. See
Table 2.
TRACKING AND CHANNEL DATA
The personality memory in the radio includes distinct
areas which are reserved for Tracking and Channel Data.
Tracking Data establishes individual radio parameters
and tailors the operation of the unit across the band. The
parameters are: high RF power, low RF power, modulation
level and receiver squelch opening. This data is programmed
into the RAM (U1) on the Control Board at the factory after
the front and rear covers are "married". The PC Programmer
allows alteration of this data if necessary.
Channel Data is the individual channel informationsuch
as TX and RX frequencies, CG information, CCT informa-
tion, and the four previously mentioned parameters. This
data is stored in the RAM on a per channel basis as each
channel is programmed. The PC Programmer allows altera-
tion of this data (on a per channel basis) if necessary.
Low, middle and high-side of the band values are pro-
grammedintotheradioforeachTrackingparameter per band
(806-825 and 851-870). When a channel is added to the
radio, the Programmer reads the Tracking Data stored in the
radio and calculates necessary values for each parameter
using a linear interpolation technique. The Programmer then
stores the newly calculated values in the Channel Data area
of memory along with the associated channel information.
Changing the Tracking Data in the radio will not alter Chan-
nel Data of previously programmed channels.
Tracking Data should not normally be altered; however,
it may be necessary to reprogram some of the values after
aligning circuitry, or replacing modules or other components
which obsolete the previously programmed values. Settings
for each parameter are listed in Table 4. If Tracking Data is
alteredfortheabovereason,itwillbenecessarytoreprogram
all channels to establish the new default data for each chan-
nel. See the Programming Manual for further information on
altering Tracking and Channel Data.
Digital values stored for the POWER SET analog volt-
age are one example of tracking information. As no two
transmitter stages are exactly matched, the POWER SET dc
voltage will be slightly different with any two radios to
produce the same power output. Tracking and Channel Data
allows the microprocessor to tailor the POWER SET line for
RF stage gain differences from unit-to-unit and across the
band.
TROUBLESHOOTING
The following procedures are designed to quickly lead
the service technician to the area of trouble. Rear and Front
Cover Assembly troubleshooting procedures are outlined.
Also see LBI-38834 for troublshooting procedures that ap-
ply to later Front Cover Assembly 19D903620G1 (less Con-
trol Board).
The test set-up should be identical to the set-up used in
the "ALIGNMENT PROCEDURES" section in this man-
ual. Table 5 lists common problems and most likely problem
areas.
REAR COVER ASSEMBLY
The troubleshooting procedures that follow primarily
assume a problem has been narrowed to a problem on the RF
Board. Transmitter, receiver and synthesizer symp-
toms/causes are outlined.
PARAMETER FACTORY SETTINGHEX VALUE*
High-Power 3.0 Watts 85
Low-Power 1.0 Watt 50
Modulation ±4.3 kHz ** 0A
Squelch Opening 8 dB SINAD A0
Table 4 - Tracking Data Parameters
*Listed hex values are approximate; final pro-
grammed values will vary from unit-to-unit and
will need to be adjusted as such.
** EXT MIC HI = 1 kHz, 110 mV rms
LBI-38632
10
