Service manual

ALIGNMENT AND TEST PROCEDURES
7-4
Month 2000
Part No. 001-2004-601
7.1.8 AUDIO DISTORTION
1. Plug a 16 ohm load at J101 or J104 on the MAC
(Main Audio Card).
2. Connect a distortion analyzer to the 16 ohm load.
3. Measure the distortion of the receive audio at J101
or J104 on the MAC with the local volume control
set to 2.8V RMS.
4. The reading shall be less than 3%.
(Typically less than 1%.)
5. Measure receive sensitivity at J101 or J104 on the
MAC.
6. The reading should be less than 0.35 µV.
(Typically 0.25 µV.)
7. The software programs the synthesizer for
1 MHz above the Receive frequency.
8. Receive sensitivity should be less than 0.35 µV.
(Typically less than 0.30 µV.)
9. The software programs the synthesizer for
1 MHz below the Receive frequency.
10.Receive sensitivity should be less than 0.35 µV.
(Typically less than 0.30 µV.)
11.Adjust the signal generator level to produce 15 dB
SINAD.
12.Adjust R219 for 0.5V ±0.02V at TP201.
7.2 EXCITER ALIGNMENT
C R I T I C A L A D J U S T M E N T
The TCXO must be adjusted within 5 minutes of turn-
ing the AC power on to the repeater. Do not under any
circumstances try to set frequency later on in any of
the tests, as TCXO frequency stability cannot then be
guaranteed.
Refer to Figure 7-2 for component locations and
Figure 7-8 for equipment needed and setup diagram.
W A R N I N G
SAFETY MEASURES ARE DISABLED IN TEST
MODE. ALARMS ARE ACTIVE. HOWEVER, FEA
-
TURES SUCH AS THERMAL SHUTDOWN IN THE
PA ARE DISABLED.
Figure 7-2 EXCITER ALIGNMENT POINTS
7.2.1 PRETEST
1. Set TCXO modulation adjust R425 fully counter-
clockwise.
2. Connect the power meter to J402.
U406
Y401
R425
U402
U405
J401
2
1
19
20
R446
U404
J402
U403
PIN 6