MFJ-616 Speech Intelligibility Enhancer
TM
Instruction
Manual
3
SET-UP INSTRUCTIONS
Power Sources:
Power your unit from any stable 12-15 Vdc source capable of delivering 1.5
Amps--including 13.8-volt high-current transceiver supplies, smaller dedicated power sources,
properly rated wall adapters, and 12-volt batteries. The MFJ-616 features supplemental internal
filtering, but hum and noise may still occur if your source is under-rated or very poorly regulated.
Protect both power leads with 2-Amp fuses when using a high-current source such as a station
supply. The controller's external power jack accepts a 5.5-mm x 2.1-mm coaxial plug. You may
obtain extra plugs from RadioShack (274-1567 or equivalent). Wire (+) voltage to center
terminal, and (-) to common, as shown:
+
-
Power Supply
+
-
2-A
2-A
Important Note: Unregulated DC sources (simple wall cubes, solar panels, etc.) may damage
your unit. Never apply more than 15 volts.
Headphones:
Use
stereo headphones rated at 8-40 Ohms impedance. The front-panel
headphone jack accepts a standard 1/4" stereo plug. If stereo phones are unavailable, you may
use monaural phones with a mono plug if JMP4 and JMP5 are removed (factory default). JMP4
and JMP5 are located on the main PC board directly behind the headphone jack.
Speakers:
For best results, use a matched pair of high quality speakers housed in properly-
designed cabinets. Acoustic suspension or ported drivers in the 4-to-6 inch range work
especially well for speech. Any voice-coil impedance between 4 and 16 ohms is acceptable.
Tweeters should be disconnected in extended-range monitors to reduce high-frequency noise
contribution. Use monaural or stereo patching, as shown below:
Stereo Plug
+
+
-
-
+
+
-
-
L
R
L
R
Mono Plugs
When preparing speaker cables, it's important to
maintain proper lead phasing
. If speakers
are cross-phased, frequency response and efficiency suffer due to acoustic cancellation.