7
SECTION 4
OPERATION
A)
Controls and indicators
FM-800 and FM-850:
Input level is controlled by a stereo (FM-850)
potentiometer, labeled
INPUT LEVEL
and located on the front panel. Two leds
indicate the modulation level:
NORMAL
(green), witch lights up when the
modulation level is equal of 50% to 100%, witch indicates a normal modulation
state that is required for an undistorted signal at the receiving end.
OVER
(red),
witch lights up when the modulation level is equal or greater than 101%, witch
indicates an
over modulation
state and could result in distortion at the receiving
end. The
OVER
indicator shall never or rarely light, in order to avoid distortion.
To allow a better perception of this indicator, its holding time has been
lengthened, because of its importance.
The
FM-850
transmitter can be switched from mono to stereo mode, in order
to let you use the best mode for your particular application. The stereo selector
is located on the front panel (
STEREO
). When in stereo mode, the
STEREO
indicator lights up. In mono mode, both inputs are active (balanced or
unbalanced).
Tuning lock:
This indicator (front panel for FM-800 & FM-850 models) will lite
up to show that your chosen FM frequency has been validated and that the RF
output is active. A delay of 3 to 4 seconds is necessary before the system
stabilize itself. This delay is mandatory in a manner to avoid frequency
scrambling while it is in the stabilization process.
Bass Boost:
This control (FM-850 only) when activated, will produce a bass
boost of 6dB from 0Hz to 100Hz.This feature will enhance the bass response
of any type of FM receivers, specially those that are not equipped with a bass
boost function.
B)
Input and output connectors
FM-800
and
FM-850
transmitters come with two sets of inputs:
RIGHT
and
LEFT XLR3
balanced inputs and
RIGHT
and
LEFT
1/4" unbalanced inputs, witch
are the two most popular types of input connectors.
The RF output has a female UHF (SO-239) connector and typical load
impedance is 50 Ohms. Antenna cable (RG-8 or RG-58) should not exceed 100
feet in length for RG-8 and 50 feet for RG-58, in order to minimize the power
loss in the cable.