Listen Technologies LR-500, LR-400, LR-300 User Manual 2

User’s Manual

LR-500 Programmable Display Receiver

LR-400 Display Receiver

LR-300 Receiver

Don’t miss a single sound. Listen.

Listen Technologies Corporation
8535 South 700 West, Suite A
Sandy, Utah 84070-2515 USA
Telephone: [phone]
Toll Free (North America): 1.800.330.0891
Fax: [phone]
E-mail: [e-mail]

Listen®and the Listen logo are registered trademarks of Listen Technologies Corporation

Welcome to Listen!

i

Dear Valued Customer,

Thank you for choosing Listen! All of us at Listen are dedicated to providing you
the highest quality products and prompt, efficient customer care. Our products are
manufactured in an ISO-9000 factory that has been independently certified to the
highest quality standards. We stand ready to answer any questions you might have
during installation or in the operation of our products. Should there be any
problems with your Listen products, we are ready to help you in any way we can.
Should you have any comments on how we might improve our products or our
service, we’re here to listen. Here’s how to reach us:

Telephone: [phone]
Fax: [phone]
Toll Free (North America): 1.800.330.0891
E-Mail: [e-mail]
Web: www.ListenTech.com

Thank you... and enjoy your listening experience!

Best regards,

The Listen Team

Listen™ and the Listen Logo are registered trademarks of Listen Technologies Corporation.

Receivers_2004_06_08 © 2004 Listen Technologies Corporation. All Rights Reserved.

Table of Contents

1

LR-500 User’s Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

LR-500 Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

LR-400 User’s Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

LR-400 Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

LR-300 User’s Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

LR-300 Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Supplementary Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Channel Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Listen SQ™ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

RF Reception Maximization Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

72 MHz Frequency Compatibility Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

216 MHz Frequency Compatibility Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Compliance Notice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

FCC Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68

Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Receivers Table of Contents

2

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3

User’s Manual

LR-500 Programmable Display Receiver

Don’t miss a single sound. Listen.

Listen Technologies Corporation
8535 South 700 West, Suite A
Sandy, Utah 84070-2515 USA
Telephone: [phone]
Toll Free (North America): 1.800.330.0891
Fax: [phone]
E-mail: [e-mail]

4

LR-500 Introduction

· LR-500 (72MHz or 216MHz)

· Warranty Card

· Receiver User Manual

LR-500 Package Contents

72 MHz: LR-500-072
216 MHz: LR-500-216

Listen Part Number

See pages 70-71.

Optional Accessories

5

LR-500 Table of Contents

Architectural Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Quick Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Operation Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Programming Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Squelch Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Squelch Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Charging Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Wall Transformer Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Supplementary Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Channel Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Listen SQ™ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

RF Reception Maximization Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

72 MHz Frequency Compatibility Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

216 MHz Frequency Compatibility Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Compliance Notice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

FCC Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68

Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Optional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

LR-500 Table of Contents

6

LR-500 Specifications

LR-500 Specifications

Architectural Specifications

The FM receiver shall be capable of receiving on 57 wide and narrow band channels with a SNR of 80dB or greater.
The receiver shall be programmable to electronically lock out unneeded channels. The receiver shall be capable of seek­ing channels. The device shall have an adjustable squelch. The device shall have an audio frequency response of 63Hz
to 15KHz, ±3dB at 72MHz, or of 63Hz to 10kHz, ± 3dB at 216MHz. The device will incorporate a stereo headset jack
that allows the user to plug in either a mono or stereo headset. The device shall incorporate an LCD display that indi­cates channel, channel lock or lock status, battery level, low battery, battery charging, and RF signal strength. The
receiver shall incorporate automatic battery charging circuitry for recharging of NiMH batteries. The Listen LR-500 is
specified.

Specifications

Specification LR-500-072 LR-500-216

RF Frequency Range 72.025 - 75.950 MHz 216.025 - 216.975 MHz

Number of Channels 57 (17 wide, 40 narrow) 57 (19 wide, 38 narrow)

Sens itivity

Frequency Accuracy

Antenna

Antenna C onnector

Squelch

Complia nce

System Frequency Response 63Hz - 15kHz (±3dB) 63Hz - 10kHz (±3dB)

System Signal to Noise Ratio
(A-we ighted)

SQ enabled: 80dB; SQ disabled 60dB SQ enabled: 80dB; SQ disabled 50dB

System Distortion

Output

Uses earphone cable

<2% total harmonic distortion (THD) at 80% deviation

.6uV typical, 1 uV max imum for 12dB SINAD

3.5mm connector

3.5mm c onnector s, unbalanced, 0 dBu nominal output lev el,
16mW maximum, impedance 32 Ohms

** All s ystem spe cificat ions are w ireles s end-to -end

± .005% stability 0° to 50°C (32° to 122° F)

Programmable in 20 steps

FCC Part 15, Industry Canada

RF

Audio

continued on next page

7

Set Up Controls
User Controls

Progr amming
LCD Display

LED
Battery Type

Battery Life (Liste n batter ies)

Battery C harging (NiMH only)

Power S upply Co nnector
Complia nce

Dimensio ns

Unit W eight

Unit Weight with batteries

Shipping We ight

Door
Temperature - Operation

Temperature - Storage

Humidity

Volume, c hannel UP/D OWN, SEEK. All c ontrols exce pt volume a re elec tronica lly lockable.

Indica tes channe l, RF signal s trength , lock sta tus, squelc h, battey po wer lev el and channe l

progr amming.

Fully automatic, 14 hours

-10° to 40°C (14° to 104° F)

-20° to 50°C (-4° to 122° F)

Unit can be pro grammed so that only des ired channels are displayed. Squelch can be
adjuste d for s ensitiv ity and signal ca pture co ntrol. Cha nnel selec tion can be locked by

holding the S EEK button 5 se conds.

Red, illuminat es when unit is on. Flas hes when b atteries are low . Flashes when char ging.

Flashes when locked and user attempts to seek to another channel

UL Listed

16mW maximum, impedance 32 Ohms

Two AA batteries, alkaline or NiMH

30 hours alkaline (LA-361), 15 hours NiMH rechargeable (LA-362)

0 to 9 5% relativ e humidity, non-conde nsing

Manually lockab le. UP, DOWN and S EEK through door , other

contr ols behind doo r (see C ontrols abo ve).

Indicators

Physical

3.0 in x 1.0 in x 5 in WxDxH (7.6cm x 2.5cm x 13.cm)

5.8 oz (164.4g)

2.3mm OD by 0.7mm ID, barrel type connector. 7.5VDC, center positive <250mA. Drop in
contact points for use with L iste n charging cases.

3.9oz (111g)

Environmental

Pro grammable c hannel sele ction (se e below), alk aline/NiMH bat teries

and sque lch, SQ enable /disable

Controls

1.0 lbs (453.6kg)

Power

LR-500 Specifications

LR-500 Specifications continued

Specification LR-500-072 LR-500-216

8

LR-500 Quick Reference

Quick Reference

LR-500 Front

3.5mm Input Jack
A Listen earpiece or headset
connects here.

LED - when lit, indicates
unit has power.

ON/OFF & VOLUME control dial

Press and hold both buttons for 5 seconds
to enter PROGRAM mode. The PGM icon
will appear in the display. To exit PROGRAM,
let unit sit idle for 5 seconds.

Look & Listen™ display shows receive
level, channel, battery status, PROGRAM
mode, whether a channel is locked, and
whether a channel is locked out from
selection (PROGRAM mode). See close­up on page 10.

Use UP and DOWN buttons to select a
channel.

SEEK button allows the user
to change channels or to
lock on a channel

Adjustable Squelch:
The default factory preset for squelch
is 03.(See page 18 for Squelch
programming information)

9

LR-500 Quick Reference

Quick Reference

LR-500 Inside Access Door

Battery Select Switch - place in NiMH position ONLY if you
are using Nickel Metal Hydride batteries, otherwise, leave it
in the Alkaline position.

SQ Switch: shipped in the ON position, use a screwdriver
or pen to slide to the OFF position if needed. You should
turn SQ off if any of your receivers do not have SQ.

SQ Switch

Battery Select
Switch

3.5mm Input Jack
A Listen earpiece or headset
connects here.

LED indicators

· Steady Red: Normal operation

· Slow Flashing: Battery is low

· Slow Flashing while charging: Unit is charging

ON/OFF and VOLUME control dial ­rotate the dial counter-clockwise to
turn unit on and increase volume.

LR-500 Top of Unit

10

LR-500 Quick Reference

Quick Reference

LR-500 Look & Listen™ Display

Dots indicate the relative RF
signal strength.

Indicates the currently
tuned channel

Indicates the unit is in PROGRAM mode.
To enter PROGRAM mode, press and hold
the UP and DOWN keys until the PGM icon
appears in the display. To exit PROGRAM
mode let unit sit idle for 5 seconds. See
page 16 for complete instructions.

When the padlock is visible the unit is
locked on channel currently displayed.
Press and hold SEEK for 5 seconds to
unlock or lock.

L/O: while in Program mode, this symbol
indicates that a channel is locked out and
will not be available to the user. Press
SEEK to toggle channels between Locked
Out and non-Locked Out modes.

Battery level indicator. The indi­cator flashes, along with the red
LED on top of the unit, to alert
you when the battery is low and
needs to be charged or
changed.

LR-500 Battery Indicator

All three segments showing:
The batteries are at 50% or
greater capacity.

One segment showing:
Your batteries less than 25% capacity. When
this segment begins flashing along with the
LED on top of the unit, you should immedi­ately change your batteries or recharge them
(if using NiMH batteries).

Two segments showing:
The batteries are at 25-49%
capacity.

11

LR-500 Setup Instructions

LR-500 Setup Instructions

Remove the product

Remove outer packaging and plastic cover. Inspect for physical damage. If damage is aparent,
please contact Listen Technologies Corporation technical sup­port for assistance. See page 69 for contact information.

Open the front access door

If locked, use a pocketknife or small screwdriver to unlock the
door locks on both sides of the unit. To unlock the door, rotate
the lock ¼ turn counterclockwise.

Grip the two tabs with your thumb and index finger and pull
the door downward. Do NOT place batteries in the unit yet.

Select Battery Type

See diagram on page 9. You have two choices: NiMH and
Alkaline. The unit is shipped with the switch in the Alkaline
position. Use a pen or small screwdriver to select the battery
type.

CAUTION: If you are using any battery type other than
rechargeable Nickel Metal Hydride (NiMH) batteries, make sure the BATTERY selection
switch is in the alkaline position.

LockedUnlocked

WARNING: Do not place the BATTERY switch in the NiMH position if you are not using
Nickel Metal Hydride Batteries. The NiMH position will attempt to charge any batteries
in the unit, even if they are not the proper type. Charging non-Nickel Metal Hydride
(NiMH) batteries will result in physical harm, destruction of property and/or fire.

12

LR-500 Setup Instructions

LR-500 Setup Instructions continued

Set SQ switch

The SQ switch is inside the battery compartment next to the Battery Select switch. The unit
is shipped with SQ in the ON position. To turn it off, use a small screwdriver or pen to slide
the switch to the OFF position (to the right). See page 58 for more information on SQ.

Place Batteries in Unit

Place two AA batteries in the compartment, making note of the battery polarity
shown in the battery compartment, and again verifying that the BATTERY
SELECT switch is in the correct position for the batteries you are using. (ALK
should be selected for all battery types other than NiMH).

NOTE: Listen uses 1800mAh (milli-Amp-hour) constant current NiMH
(Nickel Metal Hydride) batteries. These may be purchased from your Listen
dealer (ask for part number LA-362).

Battery
Select Switch

SQ Select
Switch

13

LR-500 Setup Instructions

LR-500 Setup Instructions continued

Connect an Earphone or Headset

Your headset or earphone will connect to the jack on the top of the unit. Either mono or
stereo connectors may be used with a Listen receiver. Make certain you push the plug all the
way into the jack.

Turn the Unit On

Receivers are turned on by rotating the volume
dial counterclockwise. The red LED on top of
the unit should activate and the LCD display
should illuminate. If they do not, make sure you
have installed the batteries correctly and that
you are using fully charged batteries.

Select Channel(s)

See page 56 for complete channel selection information.

Set Squelch

See pages 17 and 18 for squelch and programming information.

Program Channels

see page 16.

Red LED will illuminate
when on

Turn volume knob
counterclockwise
to turn on

LCD display will
activate when on

Earphone/Headset jack

14

LR-500 Operation

LR-500 Operation Instructions

Make Sure the Unit is On

Rotate the volume knob counterclockwise with an earphone or headset connected to the unit.
Listen receivers use the cable of the earphone or headset as a receiving antenna.

Be careful when turning the unit on - if you turn the knob too far you might get too much vol­ume in your earphone!

Select a Channel

Select the channel to match the transmission channel by pressing the UP and DOWN buttons
on the receiver.

At 72MHz:

72MHz receivers operate on 17 wide band channels and 40 narrow band channels. Channels
represented by letters on the display (i.e. A) are wideband channels ; channels represented by
numbers are narrowband channels.

At 216MHz:

216MHz receivers operate on 19 wide band channels and 38 narrow band channels. Channel
numbers starting with a “2” are wide band; channels beginning with a “1” or “3” are narrow
band channels.

Refer to the Frequency Compatibility Tables (pages 60-63) for specific frequencies and com­patibility with other manufacturers.

Test the audio

If a transmitter is broadcasting on that channel, you will be able to hear the audio. If the sig­nal is too weak, the audio will be muted (squelched).

NOTE: Listen
recommends the
use of wide band
transmitters.

15

LR-500 Operation

LR-500 Operation Instructions continued

Find an audio transmission using SEEK

Another way to find a channel on the LR-500 is to use the SEEK button. When you do
this, the Listen receiver looks for the next active channel. Sometimes the unit will mistake
interference for a real broadcast signal. If you get interference, press the SEEK button again.
The unit may stop on a channel that is close to the actual broadcast channel, in which case
the channel will sound noisy or distorted. Simply press SEEK again until you find the clear­est operating channel.

Adjust the volume control

Use the control dial on the top of the unit to adjust the volume to a comfortable
level.

To Lock into Only One Channel

Press and hold the SEEK button for 5 seconds to lock a receiver onto the currently
tuned channel. Press and hold the button again to unlock. When locked the LED
on top of the unit will flash when you press the SEEK button.

Is the Channel Locked on My Receiver?

On the LR-500, when the channel is locked, the padlock icon will appear on the display. If
the unit is locked, the red LED on the top of the
unit will flash when
you press the SEEK
button.

Padlock appears when locked

If locked, LED flashes on all
portable receivers when SEEK
button is pressed.

16

LR-500 Programming

LR-500 Programming Instructions

The LR-500 Display Receiver has some special features not available in the other receivers:
you may lock out unwanted channels, and you can adjust the squelch in the unit.

Locking Out Unwanted Channels

For applications where users are required to select a channel (such as language interpretation or
classrooms), and you don’t want them to have to go through all 57 available channels to find
the appropriate channel, you can lock out all channels except the ones you are using in your
facility.

Enter the PROGRAM mode

Press the UP and DOWN buttons simultaneously for 5 seconds, until the PGM symbol
appears in the display.

Use the UP and DOWN keys to select channels

As channels are displayed on the unit, those channels that are locked out from user
access will be indicated by the L/O (Locked Out) symbol. When a channel is locked
out, the receiver will skip over that channel when a user is tuning the receiver.

Press the SEEK button to toggle channels between locked out and

non-locked out modes

Exiting PROGRAM mode

To exit the PROGRAM mode, let the receiver sit idle (don’t press any buttons) for 5 seconds.
The receiver will automatically return to normal operation. If you haven’t finished program­ming the unit and it automatically exits, press and hold the UP & DOWN buttons simultane­ously for 5 seconds to re-enter the PROGRAM mode.

UP and DOWN buttons
on front of LR-500

17

LR-500 Squelch

LR-500 Squelch

Squelch

The purpose of squelch is to mute the audio output of your receiver when the signal from the trans­mitter is turned off or is too weak to be received. Without squelch you would hear radio noise in
your earphone. The squelch on your receiver can be adjusted so that it will mute the audio on dif­ferent RF signal strengths. This is useful as follows:

· To ensure that users don't hear transmissions from other transmitters, set the squelch setting to
the highest level that doesn't squelch the receiver.

· If the receiver is going to be close to the transmitter (i.e. in a classroom), setting the squelch
setting high so that when the transmitter is turned off it immediately squelches and ignores
transmitters in other rooms.

· If you are in an area that has a lot of inference, you may want to set the squelch setting to a
high setting to ensure the interference is not picked by the receiver.

· If you need the maximum amount of range, you may want to consider setting the squelch set­ting to a low level (0, 1 or 2). CAUTION: when setting the squelch level low the reliability
of squelch function is comprised. This will cause radio noise to be heard in the earphone and
there is a possibility of hearing damage.

18

LR-500 Squelch

Squelch Programming

To enter Squelch programming mode

· Turn the unit off

· Press and hold the seek button; while still holding seek turn the ON/OFF dial to turn the unit on.

· Release the seek button when the Listen name disappears and a two digit display is seen.

To adjust the Squelch level

· Use the Channel UP and DOWN buttons to raise or lower the squelch sensitivity settings.

· Lower numbers mean that a less powerful and possibly noisy signal will be heard, but you can have a
longer range.

· Higher numbers mean that a more powerful signal with no noise will be heard, but you may have a
shorter range.

Squelch setting 00 is no squelch; this effectively disables Squelching capabilities of the receiver. Squelch
setting 20 is maximum squelch sensitivity; you must have a very strong and stable RF signal for the unit
to not engage the squelch feature.)

Adjusting the squelch setting will keep your LR-500 receiver from picking up noise when the transmitter
is not transmitting, or when you lose the signal by being out of range or if encountering interference.

Note: For squelch settings 1-3, the squelch function is slow which allows for maximum transmission
range. For squelch settings 4-20 the squelch function is fast to ensure little radio noise is heard during the
squelch function.

(The Listen SQ feature is not squelch, please refer to page 58 for information on Listen SQ).

Squelch Programming Instructions

LR-500 Charging Batteries

19

LR-500 Charging Batteries

The LR-500 and all Listen receivers are unique because they have
SmartCharge™ chargers built in. When any of these units are connected
to an LA-202 wall transformer or dropped into a Listen charging case,
NiMH batteries will be charged.

To charge the batteries using the LA-202 wall transformer, plug the trans­former into the jack marked “PWR/CHG” on the side of the unit. The
unit can be operated while the batteries are charging.

To charge the batteries using a drop-in charger, simply place the unit into
a slot in the charger and connect the charger to power. Make sure the
unit is fully seated in its slot.

One of several charging cases available from Listen. Check the Listen
website for more details.

SmartCharge™ uses a pulse charging, which greatly extends the life of
Nickel Metal Hydride (NiMH) batteries. The entire charging process
takes 13 hours. Listen recommends that you allow the charger to com­plete its full cycle every time for maximum battery life.

IMPORTANT: In order to charge NiMH batteries, the BATTERY SELECT switch in your
Listen product must be set to the NiMH setting. Use a pen or small screwdriver to move the
switch (located in the battery compartment) to the proper position.

Connect LA-202
here and plug it
into an AC wall
outlet.

IMPORTANT: DO NOT ATTEMPT TO CHARGE ANY TYPE OF BATTERY OTHER THAN NiMH (NICKEL METAL
HYDRIDE) with your Listen equipment. Alkaline batteries may explode when connected to a

charger. Other risks of charging non-NiMH batteries include destruction of property or fire.

LR-500 Charging Batteries

20

LR-500 Charging Batteries continued

During the charge cycle, the red LED on top of the Listen product will flash slowly. When
charging is completed, the LED will turn off. It is not necessary to unplug the charger; howev­er, if you unplug the unit from the charger and then plug it back in, it will begin the 13-hour
charge cycle over again.

When not using the LR-500, it is recommended to leave the unit on the charger. The charger
provides a “maintenance” charge that keeps the battery at 100%. If the unit is not on the
charger, the battery will lose up to 20% of its charge per month.

NOTE: Listen uses 1800mAh (milli-Amp-hour) constant current NiMH (Nickel Metal
Hydride) batteries. These may be purchased from your Listen dealer (ask for part number
LA-362).

One of several charging cases
available from Listen. See
www.ListenTech.com for more
options.

LA-311 - 16-unit Drop In Charging Case shown

21

LR-500 Wall Transformer

LR-500 Wall Transformer Operation

The LR-500 will operate normally when connected to a wall transformer. Use Listen part number
LA-202, available from any Listen dealer. Connect the wall transformer to the jack on the side of
the LR-500 marked “PWR/CHG” and plug the wall transformer into a grounded AC outlet.

You do not need to have batteries installed in the LR-500 to
operate it with a wall transformer.

NOTE: If batteries are in the unit ensure that the battery
selection switch is set properly as shown on page 9. Please
review the information on page 19 for important information
regarding battery type and charging.

The LA-202 wall transformer
plugs into the side of your
portable transmitter or receiver.