Kenwood NXR-5700, Service Manual

Page: 59 / 122

(No.RA033<Rev.001>)1-59
4.8 Confirmation and Alignment of Set-up to
Prevent Receiver Desensitization
4.8.1 Confirmation of Duplexer alignment
The duplexer allows the Repeater to simultaneously transmit and
receive. To accomplish this, in the programmed receive fre-
quency, the transmit frequency must be notched or suppressed
by 75dB or more. Additionally, on the programmed transmit fre-
quency, the receive frequency must be notched or suppressed
by 75dB or more. The following figures are examples of Du-
plexer alignment using a spectrum analyzer.
4.8.2 Confirmation of Repeater Desensitization
The following figure is a Test set-up for Repeater Desensitiza-
tion.
After this Test set-up is completed, confirm the Repeater
Desensitization as mentioned below.
(1) Disable the repeater mode.
(2) Adjust the level of the RF generator until 12dB SINAD is
reached.
(3) Increase the output of the RF generator by 1dB. (This in-
creases the SINAD.)
(4) Enable the repeater mode.
(5) Read the SINAD level. It should not drop below 12dB SI-
NAD. If the SINAD is less then 12dB, check the tightness
of the connectors and the tuning of duplexer.
33. Re-
peat Gain
adjust [An-
alog Wide] FPU Test mode
1) Adjust Item: [Repeat Gain (Analog
Wide)]
Connect the Deviation Meter to the TX
ANT end via the ATT.
Deviation Meter setting
LPF: 15kHz, HPF: OFF
De-emphasis: OFF
Detector: +peak, -peak
2) Connect the SSG to the RX ANT.
SSG setting
Frequency: Desired Frequency
Output: -53dBm (501
μ V)
MOD: 1.0kHz
DEV: ±1.0kHz
Press [Transmit] button.
Deviation
meter
Oscillo-
scope
SSG Rear TX ANT
RX ANT
PC
ADJ 1.0kHz Devia-
tion ±0.05kHz
Press [Apply] button to
store the adjustment
value.
34. Re-
peat Gain
adjust [An-
alog Nar-
row] FPU Test mode
1) Adjust Item: [Repeat Gain (Analog
Narrow)]
Connect the Deviation Meter to the TX
ANT end via the ATT.
Deviation Meter setting
LPF: 15kHz, HPF: OFF
De-emphasis: OFF
Detector: +peak, -peak
2) Connect the SSG to the RX ANT.
SSG setting
Frequency: Desired Frequency
Output: -53dBm (501
μ V)
MOD: 1.0kHz
DEV: ±1.0kHz
Press [Transmit] button.
Item Condition
Measurement Adjustment
Specifications / Re-
marks
Test-
equipment
Unit
Terminal Unit
Parts Method
Ref –10dBm
#Peak
Log
10dB/
Atten 5dB
V1 V2
V3 FC
AA
#Res BW 30kHz
VBW 30kHz
Span 20MHz
Sweep 50ms (401 pts)
RX
TX
75dB or more
50
dummy
RF signal
generator
Duplexer
Repeater
Attenuated
port