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CDM-600L Field Installation Instructions
KT/11202-1 External 20 dB Step Attenuator Kit
Installation Instructions
External 20dB step attenuator kit, KT/11202-1, for the CDM-600L modem provides capability of
extending the programmable output power range down to –60dBm (-65dBm uncalibrated) from the
standard –40dBm (-45dBm uncalibrated). The following sections identify installation instructions,
relevant front panel operations and remote control commands for the KT/11202-1 External 20 dB Step
Attenuator Kit for the CDM-600L.
When the kit is installed, modem firmware (version 1.2.2 onward) provides two set-up modes for
programming output power. The normal manual power mode allows the standard 0dBm to –40dBm
(-45dBm uncalibrated) output power programming. In this mode, the external step attenuator is set to
minimum attenuation. The additional low power mode allows the output power programming from
-20dBm to –60dBm (-65dBm uncalibrated). In this mode, the external 20dB attenuator is switched in.
The external 20dB step attenuator on/off control is achieved by multiplexing a 5 volt DC relay activation
signal onto the center conductor of the transmit output connector. The external attenuator design will not
tolerate BUC power supply voltages, and will not pass 10MHz BUC frequency reference or BUC FSK
control signals. Hence, the external attenuator kit is NOT applicable in applications where the modem
must supply BUC power supply, 10MHz frequency reference, or FSK control. The external 20 dB step
attenuator kit includes three parts:
1. PL/11141-1 attenuator module
2. CA/WR11177-1 kit installation ID plug, and
3. CA/WR11178-1 5V on/off control jumper plug.
#1 – PL/11141-1
Attenuator Module
Figure 1. KT/11202-1 External 20 dB Step Attenuator Kit
Figure 1 shows the installation of these kit items in the modem. The two jumper plugs must be installed
inside the modem so that installation of the kit requires removal of the modem cover. CA/WR11177-1
mates with 6-pin connector J3 on the modem top board PL/9662-x. This jumper plug creates an
identification signal that indicates to the modem firmware that the external attenuator kit is installed.
Introduction
3
#2 – CA/WR11177-1 ID Plug
#3 – CA/WR11178-5 On/Off
Control Jumper Plug
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