Question:  I have an Eclipse frame that I'm adding additional interface cards to, unfortunately the rack with the Eclipse frame doesn't have an additional 7RU of rack space to support an IMF-3 frame, 2 PSU-101s and 2RU of blank space to allow for ventilation. How far away from the Eclipse frame can I place the IMF-3 / PSU-101s?
Answer:  It is important to place an interface frame in a convenient location, so that you can access the controls on the front panel and the connectors on the rear panel. Leave at least 2 inches (5 cm) of clearance at the rear of an interface frame to allow for cable connectors and access to rear-panel controls.
Usually interface module frames are located near the matrix, but they can be located farther away. The maximum recommended distance between an Eclipse matrix and an IMF-3 or IMF-102 interface frame is 500 feet (150 meters).
If redundant PSU-101 power supplies are used for interfaces, mount them at the same location as the remoted interface frames.  It is required that you leave an extra rack unit (1.75 in. or 44.45 mm) above and below each external power-supply unit. This allows for needed cooling for larger system loads.