MFJ-616 Speech Intelligibility Enhancer
TM
Instruction
Manual
4
Radio Connections:
The
Speech Intelligibility Enhancer
TM
accepts signals in the "line-level"
range from any of the following sources:
1. Auxiliary Jack:
Many larger transceivers provide an
Auxiliary Audio
output jack on the back
panel. This source may or may not be tied to the radio's volume control. Before using the
auxiliary line, be sure to check your transceiver manual for specifications. The
Speech
Intelligibility Enhancer
TM
input jacks are terminated at 500 Ohms. If your radio's auxiliary
output line has a significantly higher driving impedance (10K for example), use the external
speaker jack or headphone jack instead.
2. Headphone Jack:
Many transceivers provide a
Headphone Jack
which disables the radio's
internal speaker. This line is generally tied to the radio's output amplifier and often provides
attenuation to prevent overdriving headsets. Due to attenuation, a higher setting of the radio's
volume control may be necessary to drive the Station Master. In many cases, this condition is
desirable--the higher setting may over-ride residual amplifier noise and provide better signal-to-
noise performance.
3. External Speaker Line:
Virtually all transceivers provide an
External Speaker
Jack
that
disables the internal speaker and routes audio directly to an external load. This line may be
connected to either input A or B, but a 10-Ohm termination resistor should be installed at the
speaker plug to replace the load normally provided by the speaker. If drive from the external
speaker line seems excessive, you may add attenuation in the form of a series resistor to reduce
the level (see below):
10
A or B
10
100
To Ext Spkr
To Input
With Attenuation
With No Attenuation
SPEECH INTELLIGIBILITY ENHANCER OPERATION
Power
Console
Master
Transceiver
A
Transceiver
B
Speaker
Left
Speaker
Right
Phones
Connect your
Speech Intelligibility Enhancer
TM
as shown. Monitor speakers should be separated
by at least three feet (preferably more) for best results. They may be wall mounted or placed at
desk level. If possible, position each speaker equidistant from the "center" operating position and
at equal height above the desk.