400 SERIES INSTALLATION MANUAL Page 3-7
P/N 190-00140-02 Page Rev L
3.8 400 SERIES UNIT INSERTION AND REMOVAL
The 400 Series unit is installed in the rack by sliding it straight in until it stops, about 1 inch short of the
final position. A 3/32“ hex drive tool is then inserted into the access hole at the bottom of the unit face.
Rotate the hex tool clockwise while pressing on the left side of the bezel until the unit is firmly seated in
the rack. It may be necessary to insert the hex drive tool into the access hole and rotate the mechanism 90°
counterclockwise to insure correct position prior to placing the unit in the rack.
To remove the unit from the rack, insert the hex drive tool into the access hole on the unit face and rotate
counterclockwise until the unit is forced out about 3/8 ” and can be freely pulled from the rack.
Be sure not to over tighten the unit into the rack. The application of hex drive tool torque exceeding
15 in•lbs can damage the locking mechanism.
3.9 COM ANTENNA INSTALLATION CHECK (GNC 420 AND GNS 430)
Check for insertion loss and VSWR (voltage standing wave ratio). VSWR should be checked with an in-
line type VSWR/wattmeter inserted in the coaxial transmission line between the transceiver and the
antenna. The VSWR should be inserted as close to the transceiver as possible. When rack and harness
buildup is performed in the shop, the coax termination may be provisioned by using a 6” inline BNC
connection. This would be an acceptable place to insert the VSWR. Any problem with the antenna
installation is most likely seen as high reflected power. A VSWR of 3:1 may result in up to a 50% loss in
transmit power.
