Manual

M175
Controls and Functions
Mic Jack
The MIC JACK is a locking micro jack that supplies
“phantom power” for electret microphones such as the
Lectrosonics M119, M140 Lavalier and the HM142V,
HM152V and HM162 headset models. Insert the
microphone cord plug into the jack and
rotate it clock-
wise to lock it
. It is important that the plug be securely
locked, since the microphone cord serves as the
antenna for the transmitter.
Power ON/OFF
The POWER ON/OFF switch turns the power on and
off. The switch should be left in the OFF position when
the transmitter is not in use. When the switch is in the
ON position, the battery will be drained even though the
transmitter is not being used.
Battery Indicator Lamp
The BATTERY INDICATOR LAMP will light when the
transmitter is turned on and will stay lit as long as the
battery is good. As the battery voltage drops, the lamp
will grow dim and finally go out.
Mic Level Adjust
The MIC LEVEL ADJUST is a recessed screwdriver
adjustment used to match the gain of the transmitter to
different microphones, individual voices or other audio
inputs such as tape deck outputs.
Audio Switch
The AUDIO SWITCH (M175-LS only) is a toggle type
on-off switch used to shut off the audio signal without
shutting off the RF carrier of the transmitter.
Note: The M175DC, Digital Code Squelch version
is operationally identical to the standard M175.
Battery Instructions
The battery you use in the M175 Series transmitter
should be a 9 Volt lithium or alkaline, available almost
everywhere. A lithium 9 Volt battery will provide the
best performance with over 30 hours of operation. An
alkaline battery will provide up to 15 hours of operation,
and carbon zinc batteries, even if marked “heavy duty”
will only provide about 4 hours of operation. Recharge-
able batteries made to look like 9 Volt batteries typically
only produce 7.2 Volts at full charge, which will only
operate the transmitter for an hour or less. Make sure
your batteries are marked “alkaline.” Short battery life is
almost always caused by weak batteries or batteries of
the wrong type.
The BATTERY LAMP will light when the transmitter is
turned on and will stay lit as long as the battery is good.
As the battery voltage drops, the lamp will grow dim
and finally go out. Even after the lamp goes out, there
may still be up to an hour or more of operating time
remaining. When the battery voltage is too low for
proper transmitter operation, the sound from the
wireless system may be distorted, intermittent or totally
absent. When the transmitter is first turned on, the
lamp may light for a short while even with a bad battery.
It is good practice to check the brightness of the lamp
after the transmitter has been on for several minutes
and to note the brightness occasionally during use.
To replace the battery, open the bottom battery door
cover with your thumb, rotate the door until it is perpen-
dicular with the case and allow the battery to fall out of
the compartment into your hand. It is difficult to install
the battery backwards. Observe the large and small
holes in the battery contact pad before inserting a new
battery. Insert the contact end of the battery first,
making sure the contacts are aligned with the holes in
the contact pad, and then swing the door closed. You
will feel it snap into place when it is fully closed.
To open the battery
compartment door, push the
door up and away from the case
with your thumb, then swing
open.
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LECTROSONICS, INC. 4