Kenwood TKR-850 Service Manual page 45

Item Condition
34. Power 1) CH : 2 (High power)
down detect
(High)
(Low) 2) CH : 2 (Low power)
Confirmation and Alignment of Set-up to
Prevent Receiver Desensitization
1. Confirmation of Duplexer alignment
The duplexer allows the Repeater to simultaneously trans-
mit and receive. To accomplish this, in the programmed re-
ceive frequency, the transmit frequency must be notched or
suppressed by 75dB or more. Additionally, on the pro-
grammed transmit frequency, the receive frequency must be
notched or suppressed by 75dB or more. The following fig-
ures are examples of Duplexer alignment using a spectrum
analyzer.
Ref –10dBm
Atten 5dB
# Peak
Log
10dB/
V1 V2
V3 FC
AA
TX
#Res BW 30kHz VBW 30kHz
ADJUSTMENT
Measurement
Test-
Unit
equipment
Power meter Rear
RX
Span 20MHz
Sweep 50ms (401 pts)
Adjustment
Terminal Unit Parts
TX ANT PC adj.
About 16W
(Factory-default)
PC adj.
About 10W
(Factory-default)
2. Confirmation of Repeater Desensitization
The following figure is a Test set-up for Repeater Desensi-
tization.
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
SINAD. If the SINAD is less then 12dB, check the tight-
ness of the connectors and the tuning of duplexer.
Duplexer
Repeater
TKR-850
Specifications/Remarks
Method
Attenuated
port
50Ω
dummy
RF signal
generator
45