Confirmation And Alignment Of Set-Up To Prevent Receiver Desensitization; Confirmation Of Duplexer Alignment; Confirmation Of Repeater Desensitization - Kenwood TKR-750 Service Manual

Item Condition
35. Repeat 1) VCO-A CH (TX VCO A center) SSG
gain level VCO-B CH (TX VCO B center)
(Wide) SSG output : –53dBm
SSG MOD : 1kHz
SSG DEV : 1kHz
Deviation meter filter
HPF : OFF
LPF : 15kHz
De-emphasis : OFF
Transmission
(Narrow) 2) VCO-A CH (TX VCO A center)
VCO-B CH (TX VCO B center)
Transmission
When "RF Power Down Detect" is programmed in the AUXO function, threshold of transmission output is set with the following menu.
36. 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
Rear
MOD ANA
or
Deviation
meter
Oscilloscope
Power meter Rear
RX
Span 20MHz
Sweep 50ms (401 pts)
Adjustment
Terminal Unit Parts
RX ANT PC adj.
1kHz
TX ANT
TX ANT PC adj.
About 20W
(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-750
Specifications/Remarks
Method
± 0.1kHz
Attenuated
port
50Ω
dummy
RF signal
generator
45