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Aggressive AC input filtering is utilized at the AC input of the FM-4, however it is
always advisable to use external surge protection and/or an uninterruptible power
supply (UPS), especially where AC power quality can be questionable such as at
a remote transmitter site.
Power conditioning, surge suppression and even power backup devices are wise
investments when using sensitive modern electronic devices such as the FM-4,
which for all practical purposes, is a ‘computer’.
The use of a UPS (uninterruptible power supply) is a good idea and will protect
the FM-4 from short duration power interruptions which can cause the unit to
reboot. During boot up, audio is interrupted for approximately 15 seconds.
Rack Mounting
The FM-4 is designed to fit into an industry-standard 19” equipment rack and
requires one rack unit (1.75 inches) of vertical space.
The FM-4 does not have, nor need, top or bottom cover vent holes. Latent heat is
vented out of the enclosure by natural convection through slots in the top of the
rear panel. Cooler air is drawn into the unit through vertical slots positioned lower
in the side panels.
The FM-4 may be mounted between other devices in the equipment rack, and in
accordance with good engineering practice should not be mounted directly above
devices that generate significant amounts of heat. If such a location is
unavoidable, then it is advisable to utilize an extra 1RU blank rack panel between
the FM-4 and devices immediately above and/or below it.
Installation Tips
Always place surge protection circuits as close as possible to the FM-4 or other
devices being protected.
Establish a low impedance common ground in your facility and try to route all
grounds to that point.
Choose the best power conditioning / UPS units that you can afford and suitable
for your equipment - focus on the features and options you need. High quality
UPS products can prevent thousands of dollars in equipment damage – some
even come with an external equipment damage warranty.
Unbalanced audio connections to the FM-4 should be made with shielded two-
conductor cable such as Belden 8451 or 9451 as if connecting a balanced
source. At the unbalanced source’s
output
connect the + Output to the HI input
wire and connect the source GND wire to the LO wire. Connect the shield at the
FM-4 end only
.
