TM 11-7440-232-12 / NAVELEX 0967-LP-275-5010
c. The MD-701BIUY uses an RFI shielded modem shelf.
d. The MD-701/UY and MD-701A/UY use an unshielded modem shelf.
e. Refer to paragraph 1-10 for the plug-in modules and modem shelf used in each model of the Digital Data
Modem.
f. The location and function of each module are described on the following pages.
RFI Shielded Modem Shelf Code A 46870 used in MD-701BIUY provides electrically and magnetically shielded
mounting facilities and electrical connections for one complete modem that consists of a power supply and nine plug-in
modules and a module extender.
The RFI Shielded Modem Shelf is wired for a duplex set consisting of a digital data transmit branch and a digital
data receive branch.
The RFI Shielded Modem Shelf occupies two mounting spaces on a standard 19-inch equipment rack.
Code A provides a stable 4.8. MHz crystal clock RF oscillator that mounts in shelf position A9. Position A9 is
equipped with a front retainer plate. This position also has a bracket that holds the oscillator output and ground test
points. The retainer plate contains a center hole, which allows frequency adjustment of the oscillator.
A termination panel at the rear of the shelf allows external connections to be made by bare or spade-lug terminated
wire or cable. The panel is constructed of a barrier terminal strip, interconnecting cable with connectors, and a metal
housing.
Modem Shelf*46880 used in MD-701/UY and MD-701A/UY provides unshielded mounting facilities and electrical
connections for one complete modem that consists of a power supply and up to nine plug-in modules and a module
extender. (*Code AB) .
The modem shelf is wired for a duplex set consisting of a digital data transmit branch and a digital data receive
branch.
Modem shelf Code A provides a termination panel at the rear of the shelf. This panel allows external connections
(other than ac power and primary protective ground) to be made by bare or spade-lug terminated wire or cable. The
panel is constructed of a barrier terminal strip, interconnecting cable with connectors, and a metal housing.
Modem Shelf Code B provides a stable 4.8-MHz crystal clock RF oscillator that fits in modem shelf position A9.
Position A9 is equipped with a front retainer plate. This position also has a bracket that holds the oscillator output and
ground test points. The retainer plate contains a center hole, which allows frequency adjustment of the oscillator.
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