Lectrosonics Inc UH400E Manuel D’Utilisation

UH400A/UH400TM

LECTROSONICS, INC.

This transmitter may be used with a wide variety of mi-

crophones. The 3-pin XLR connector allows the trans-

mitter to be used with any dynamic microphone, as well

as many two wire positive bias lavaliere systems (such

as those supplied by Lectrosonics).

Power Switch

The three position switch turns the unit on or off, and

selects either phantom power, or no phantom power.

Regardless of which position the switch is set, the pilot

tone muting system effectively prevents “thumps” or

transients from occurring during power up or power

down.
The PHTM (center) position of the power switch turns

on the phantom power value selected by the Phantom

Power Voltage Select switch, while the NO PHTM (fully

on) position disables phantom power.

Note: In order to avoid damage to some

microphones, be careful to use the center (PHTM)

position only when necessary and keep the

Phantom Power Voltage Select switch in the 5

V position. (See Phantom Power Voltage Select

switch.)

Power ON/OFF LED

This LED glows green when the battery is good. When

the lamp glows red, there will be about 20 minutes of

battery life left with an alkaline battery. The lamp will

blink red when there are only a few minutes of life re-

maining.

Note: A NiMH battery will give little or no warning

when it is depleted. If you wish to use NiMH

batteries in this unit, we recommend installing a

fully charged batteries, noting the length of time

that the batteries will run the unit and in the future

use somewhat less than that time to determine

when the battery needs to be replaced.

A weak battery will sometimes light the POWER LED to

the “good” green indication immediately after being put

in the unit, but will soon discharge to the point where the

LED will go red or shut down (just like a flashlight with

“dead” batteries). If the Power LED fails to light when

power is applied, replace the battery.

Phantom Power Voltage Select Switch

Note: The UH400TM can be used with the

Earthworks M30 Test Microphone if pins 2 and 3

are reversed. A barrel adapter is provided for this

purpose.

This switch selects from three phantom voltages when

the PWR switch is in the mid position. The voltages are:

• 5 Volts for lavaliere microphones,
• 15 Volts for some professional mics requiring high

current and for many common stage mics that will

operate over a wide phantom Voltage range of 12 to

48 Volts. With the proper adapter, this position can

also be used with T power microphones. See our

web site for details on finding or making the proper

adapter.

• 48 Volts for microphones that do in fact require a

supply greater than 18 Volts. (See below for a dis-

cussion of why 42 and not a “true” 48 Volts.)

For longest battery life use the minimum phantom volt-

age necessary for the microphone. Many stage micro-

phones regulate the 48 Volts down to 10 Volts internally

anyway, so you might as well use the 15 Volt setting and

save some battery power. If you are not using a micro-

phone for the input device, or are using a microphone

that does not require phantom power, set the Power

Switch to the NO PHTM position (No Phantom Power).

This is the fully up position of the Power Switch. Phan-

tom power should only be used with a fully floating,

balanced device such as most microphones with a 3-pin

XLR connector. If you use the phantom power with an

unbalanced device or if pins 2 or 3 are DC connected

to ground, then you will draw maximum current from the

power supply. The UH400A is fully protected against

such shorts but the 9 Volt battery will be drained at

twice its normal rate.

Controls and Functions

1.6MHz

100kHz

0 1

1.6MHz

100kHz

PHTM

NO PHTM

PWR OFF

LEVEL

15V

POWER
SWITCH

PHANTOM POWER

VOLTAGE SELECT

POWER
ON/OFF
LED

INPUT
JACK

MIC LEVEL

Top View

Control Panel

MODULATION LEDS

-10

-20

INPUT
JACK

Side View

FREQUENCY SWITCHES

(BEHIND DOOR)

FREQUENCY