Lectrosonics LM User Manual

INSTRUCTION MANUAL

LM/IM

Frequency-Agile UHF Belt-Pack Transmitters

Featuring

Digital Hybrid Wireless™ Technology

(US Patent Pending)

Fill in for your records:

Serial Number:

Purchase Date:

Rio Rancho, NM, USA
www.lectrosonics.com

LM/IM

LECTROSONICS, INC. 2

Frequency-Agile UHF Belt-Pack Transmitter

Table of Contents

Introduction ............................................................................................................................................................................................4

Digital Hybrid Technology .....................................................................................................................................................................4

Input Limiter ..........................................................................................................................................................................................5

No Pre-Emphasis/De-Emphasis ........................................................................................................................................................... 5

Pilot Tone Squelch ................................................................................................................................................................................5

Wide-Band Deviation ............................................................................................................................................................................5

Long Battery Life .................................................................................................................................................................................. 5

Frequency Agility ..................................................................................................................................................................................5

Antenna ................................................................................................................................................................................................5

Controls and Functions ......................................................................................................................................................................... 6

Mic Input Jack.......................................................................................................................................................................................6

Power ON/OFF Switch ......................................................................................................................................................................... 6

Power LED ............................................................................................................................................................................................ 6

Frequency Select Switches ..................................................................................................................................................................6

Modulation LEDs ..................................................................................................................................................................................6

Audio Level ...........................................................................................................................................................................................6

Antenna ................................................................................................................................................................................................6

Belt Clip ................................................................................................................................................................................................6

Battery Installation .................................................................................................................................................................................7

Operating Instructions ..........................................................................................................................................................................8

Selecting Compatibility Mode ...............................................................................................................................................................8

Attaching a Microphone or Musical Instrument and Adjusting Audio Levels ........................................................................................8

Adjusting the Transmitter Frequency ....................................................................................................................................................9

5-Pin Input Jack Wiring ........................................................................................................................................................................ 10

RF Bypassing .....................................................................................................................................................................................10

Line Level Signals .............................................................................................................................................................................. 11

Wiring Hookups for Different Sources ................................................................................................................................................11

Wiring Diagram for MI33A Instrument Cable ......................................................................................................................................11

Troubleshooting ...................................................................................................................................................................................12

Specifications and Features ............................................................................................................................................................... 13

Service and Repair .............................................................................................................................................................................14

Returning Units for Repair ..................................................................................................................................................................14

The LM and IM transmitters are FCC type accepted under Part 74: 536-608 MHz and 614-806 MHz

Rio Rancho, NM 3

LM/IM

Introduction

Thank you for selecting the Lectrosonics LM or IM
frequency agile, belt-pack transmitter.

The design of these transmitters introduces at a moder­ate cost the advanced technology and features of a
Lectrosonics belt-pack transmitter. The design is based
on the Digital Hybrid Wireless™ system (US Patent
Pending) which combines a digital audio chain with an
analog FM radio link. This digital process eliminates the
compandor and its problems, yet preserves the ex­tended operating range of the finest analog wireless
systems. The IM is offered as part of the IS400 pack­age and differs slightly from the LM in that its low-end
frequency response has been optimized for use with
musical instruments.

Both transmitters also preserve your investment. They
can emulate the compandor found in Lectrosonics 100
Series, 200 Series and IFB transmitters, and certain
transmitters from other manufacturers. (Call Lectroson­ics for more details.) Changing the compatibility mode
is accomplished with a simple procedure that does not
require opening the unit.

Mechanically, the assemblies are rugged, machined
aluminum packages with removable, stainless steel wire
belt clips. Their input jack is a standard Lectrosonics 5­pin type for use with electret lavaliere mics, dynamic
mics and line level signals. LEDs are provided on the
front panel to make quick and accurate level settings
without having to view the receiver. The battery com­partment accepts any 9 volt battery (alkaline or lithium
recommended) and makes a positive connection via
self-adjusting contacts. The antenna is a super-rugged,
permanently attached 1/4 wavelength design made of
flexible galvanized steel cable.

Only the LM and IM transmitters are covered in this
manual. Companion receivers are covered in separate
manuals.

The Digital Hybrid Wireless™ system uses 75 kHz wide
deviation for an extremely high signal to noise ratio. The
switching power supplies provide constant voltages to
the transmitter circuits from the beginning (9.3 VDC) to
the end (5.5 VDC) of battery life. The input amplifier
uses an ultra low noise operational amplifier (op amp)
for quiet operation. It is gain controlled with a wide
range dual envelope input limiter that tames input signal
peaks over 30 dB above full modulation.

Digital Hybrid Technology

All wireless links suffer from channel noise to some
degree, and all wireless microphone systems seek to
minimize the impact of that noise on the desired signal.
Conventional analog systems use compandors for
enhanced dynamic range, at the cost of subtle artifacts
(known as “pumping” and “breathing”). Wholly digital
systems defeat the noise by sending the audio informa­tion in digital form, at the cost of some combination of
power, bandwidth, operating range and resistance to
interference.

The Lectrosonics Digital Hybrid Wireless™ system
overcomes channel noise in a dramatically new way,
digitally encoding the audio in the transmitter and
decoding it in the receiver, yet still sending the encoded
information via an analog FM wireless link. This
proprietary algorithm is not a digital implementation of
an analog compandor but a technique which can be
accomplished only in the digital domain. (The patent is
still pending, so we cannot publish detailed information.)

Channel noise still has an impact on received signal
quality and will eventually overwhelm the receiver. The
Digital Hybrid Wireless™ system simply encodes the
signal to use a noisy channel as efficiently and robustly
as possible, yielding audio performance that rivals that
of wholly digital systems, without the power, noise and
bandwidth problems inherent in digital transmission. As
always, these advantages come at a cost. The Digital
Hybrid Wireless™ system requires fairly intensive
digital processing in both the transmitter and the
receiver. These processors cost money, take up space
and consume power. The Digital Hybrid Wireless
system also requires that the underlying RF link be of
excellent quality, with better frequency response and
distortion characteristics than that required by conven­tional analog wireless systems.

Because it uses an analog FM link, Digital Hybrid
Wireless™ enjoys all the benefits of conventional FM
wireless systems, such as excellent range, efficient use
of RF spectrum, and long battery life. However, unlike
conventional FM systems, Digital Hybrid Wireless™ has
done away with the analog compandor and its artifacts.

TM

LECTROSONICS, INC. 4

Frequency-Agile UHF Belt-Pack Transmitter

Input Limiter

The transmitters employ a digitally-controlled analog
audio limiter prior to the analog-to-digital converter. The
limiter has a range greater than 30 dB for excellent
overload protection. A dual release envelope makes
the limiter acoustically transparent while maintaining
low distortion. It can be thought of as two limiters in
series, connected as a fast attack and release limiter
followed by a slow attack and release limiter. The limiter
recovers quickly from brief transients, so that its action
is hidden from the listener, but recovers slowly from
sustained high levels, to both keep audio distortion low
and preserve short term dynamic changes.

No Pre-Emphasis/De-Emphasis

Because the signal to noise ratio of the hybrid system is
so high, there is no need for conventional pre-emphasis
(HF boost) in the transmitter and de-emphasis (HF roll
off) in the receiver. Thus, the possible distortion prob­lems associated with pre-emphasis and de-emphasis
are eliminated.

Pilot Tone Squelch

The hybrid system uses one of 256 different ultrasonic
tones between 25 and 32 kHz, that modulate the carrier
to operate the receiver squelch. The pilot tone fre­quency is chosen according to which of the 256 chan­nels has been selected by the frequency switch setting.
The benefit of a pilot tone squelch system is that the
receiver will remain muted until it receives the pilot tone
from the matching transmitter, even if a strong RF

signal is present on the carrier frequency of the system.
The 400 Series extends this concept even further by
insuring that all transmitters in a system have different
pilot tone frequencies so that even spurious RF from
the wrong transmitters can’t open the receiver squelch.

Wide-Band Deviation

By employing ±75 kHz diviation, Lectrosonics dramati­cally improves the capture ratio, signal to noise ratio
and AM rejection of our wireless system.

Long Battery Life

The use of switching power supplies throughout the
design allows over 6 hours of operation using a single 9
volt alkaline battery and over 13 hours of operation with
a 9 volt lithium battery. The battery contacts are spring
loaded to prevent “rattle” as the unit is handled.

Frequency Agility

The transmitter section uses a synthesized, frequency
selectable main oscillator. The frequency is extremely
stable over a wide temperature range and over time.

Two rotary switches, located on the side panel of the
unit, provide 256 frequencies in 100 kHz steps over a

25.5 MHz range. This alleviates carrier interference
problems in mobile or traveling applications.

Antenna

The antenna consists of a permanently attached
flexible, unbreakable 1/4 wavelength galvanized steel
cable.

1
2

3

4
5

Mic

Jack

+5V Bias
Supply

Hi/Lo
Pass
Filter

Bicolor

Modulation

LEDs

<--See

Shunt

Limiter

Phase Locked Loop

11.3 MHz

Reference

5-Pin Input Jack Wiring

Input
Amp

Audio
Level

Freq

Switches

Audio

11001001

Microprocessor

for details.

A-D

Converter

Digital Signal Processor

D-A

Converter

11001001

Vol tage

Controlled

Oscillator

Encoded

Audio +

Pilot Tone

9V

Battery

Final

Amplifier

Block Diagram

Switching

Powe r

Supply

Bicolor
Powe r
LED

+3.3v
+1.8v
+9v
+5v

-3v

Rio Rancho, NM 5

LM/IM

Controls and Functions

Mic Input Jack

The 5-pin (Switchcraft TA5F compatible) input accom­modates virtually every lavaliere, hand-held or shotgun
microphone available, and most musical instrument
signals. Line level signals can also be accommodated.
(See 5-Pin Input Jack Wiring.)

Power ON/OFF Switch

The Power ON/OFF switch turns the transmitter on and
off. A pilot tone muting system prevents “thumps” or
transients from occurring at the reciever even if the
transmitter is abruptly switched on or off.

Power LED

The Power LED glows green when the transmitter is
operating and the battery is good. It turns red when the
battery voltage drops to 6.1 VDC and starts blinking red
when the voltage drops to 5.6 VDC. When using a
recommended lithium or alkaline battery, there will be
about 30 minutes of operating time remaining when the
Power LED first begins blinking red.

Note: A weak battery will sometimes cause the
Power LED glow green, but it will soon discharge
to the point where the Power LED will glow red or
go out completely. If in doubt, replace the battery
with a known new battery. If the Power LED fails
to glow when the transmitter is turned on, replace
the battery.

NiMH batteries give little or no warning when they are
depleted. If you wish to use NiMH batteries in the
transmitter, you will need to manually keep track of the
operating time. Start with a fully charged battery, then
measure the time it takes for the Power LED to go out
completely. A number of Lectrosonics receivers incor­porate a Battery Timer function which tracks the amount
of time the transmitter signal is detected (See your
receiver manual to determine if this function is avail­able.) By using the receiver’s battery timer and replac­ing the transmitter battery before the premeasured time
is up, users can minimize potential loss of audio when
NiMH batteries are used.

Frequency Select Switches

Two 16-position rotary Frequency Select Switches,
accessed through the left side panel, are used to adjust
the transmitter’s operating frequency. These switches
are labeled 1.6M and 100K. The 1.6M switch is used
for coarse frequency adjustments and the 100K is used
for fine frequency adjustment.

Modulation LEDs

The Modulation LEDs provide a visual indication of the
input audio signal level from the microphone or musical
isntrument. These two bicolor LEDs can glow either red
or green to indicate modulation levels.

(LM Shown for illustrative purposes)

Belt Cip

Mic Input

AUDIO LEVEL

control

Power LED

Antenna

Battery Compartment Door

Frequency Select

Switches

The Modulation LEDs are also used to indicate the
Compatibility Mode when the transmitter is initially
turned on. The Modulation LEDs will blink simulta­neously:

• Once for 100 Series mode

• Two times for 200 Series mode

• Three times for mode 3

• Four times for Digital Hybrid Wireless
or 400 Series mode

• Five times for IFB mode

Belt Cip

Attachment Holes

Jack

Modulation

LEDs

Power

ON/OFF

™

Audio Level

The AUDIO LEVEL control is used to set the level of the
transmitter’s input for the proper modulation.

Antenna

The flexible, insulated galvanized steel cable antenna
supplied with the transmitter is cut to 1/4 wavelength of
the center of the frequency block (the frequency range)
of the transmitter.

Belt Clip

The belt clip may be removed for special applications by
pulling the ends out of the holes in the sides of the
case. An optional hinged belt clip (P/N BCHINGED) is
also available. Contact a Lectrosonics sales represen­tative, or visit our web site (www.lectrosonics.com) for
more details.

LECTROSONICS, INC. 6

Battery Installation

2

The transmitter is powered by a standard 9 volt battery.
We recommend using alkaline or lithium batteries for
longest life. Standard zinc-carbon batteries marked
“heavy-duty” or “long-lasting” are not adequate.
Alkaline batteries provide over six hours of operation at
room temperature. Lithium batteries can provide up to
13 hours and will work at lower temperatures. The
battery status circuitry is designed for the voltage drop
over the life of alkaline batteries. NiMH rechargeable
batteries will also work; although they provide fewer
hours of operation and will run down quite abruptly.
Because of this, using the Power LED to verify battery
status is not reliable with NiMH batteries; although, it
may be possible to track battery status using the
Battery Timer function available in a number of
Lectrosonics receivers. (Refer to the associated
receiver manual to determine if this function is available
in your situation.)

To replace the battery, push up on the Battery Com­partment Door and rotate it clockwise. (See illustra­tion.) Remove the old battery and take note of the
polarity marked inside showing the location of the
positive (+) and negative (-) terminals. (You can see
the large and small contact holes inside the battery
compartment with the door open.)

Insert the new battery correctly and close the Battery
Compartment Door by reversing the opening proce­dure. If the battery is inserted incorrectly, the door will
not fully close. Do not force the door closed.

Warning: Care should be taken not to leave a
fully discharged lithium battery in the
transmitter, as swelling of the battery can
make it difficult to remove from the
compartment.

Frequency-Agile UHF Belt-Pack Transmitter

1

Rio Rancho, NM 7

LM/IM

Operating Instructions

Selecting the Compatibility Mode

All units with serial number 601 and up are capable of
working with Lectrosonics 400 Series Digital Hybrid
Wireless
some non-Lectrosonics analog wireless receivers
(contact the factory for details). The transmitter must be
set to the operating mode of the matching receiver,
which is easily done using only the supplied screwdriver
and a battery.

1) Ensure the battery is good.

2) Turn OFF the transmitter.

3) With a small screwdriver (one is included with your

4) Toggle the power switch ON briefly – just long

5) Change the Frequency Select Switches to one of

6) Toggle the power switch ON, then OFF again.

7) Change the Frequency Select Switches to 0,0.

8) Turn the transmitter ON to complete the operation.

™

, 200 Series analog, 100 Sseries analog and

NOTE: The unit is supplied from the factory as a
400 series transmitter.

unit), set the Frequency Select Switches to CC. (for
Change, Change).

enough for the LED’s to light up and then turn it OFF.

the following settings:

• 100 Series mode: 1,1

• 200 Series mode: 2,2

• Mode 3: 3,3

• 400 Series mode: 4,4

• IFB Series mode: 5,5

• Mode 6: 6,6

The LEDS will blink to indicate the selected com­patibility mode. Immediately after power up, all
LEDS will blink together red, then green, followed
by the audio level LEDs (-20 and -10) blinking to
indicate the mode.

The LEDs will blink:

• Once for 100 Series mode

• Two times for 200 Series mode

• Three times for some other receivers

• Four times for 400 Series mode

• Five times for IFB mode*

• Six times for Mode 6

Note: Each time the transmitter is turned on, the
Power LED will confirm the current operating
mode with the number of blinks listed in Step 2.
The mode setting will not change until it is reset
with the procedure listed above.

Frequency Select Switch Settings (C,C)

1.6M 100K

0

1

F

2

E

3

D

C

4

5

B

6

A

9

7

8

0

1

F

2

E

3

D

C

4

5

B

6

A

9

7

8

Attaching a Microphone or Musical
Instrument and Adjusting Audio Levels

The front panel Modulation LEDs indicate input level
and limiter activity. (See Modulation LED Signal Level
Chart.) Since the distortion introduced by the limiter is
minimal and full modulation is assured, occassional
brief forays into the red by the -20 LED is acceptable.

Different voices, or instruments, will usually require
different settings of the AUDIO LEVEL control, so check
this adjustment as each new person uses the system.
If several different people will be using the transmitter
and there is not time to make the adjustment for each
individual, adjust it for the loudest voice.

Musicians also vary their volume depending on the
nature of the music. It is suggested that the transmitter
be adjusted for the passage with the loudest volume.

1) If necessary, install a fresh battery.

2) Insert the 5-pin into the MIC input jack. Ensure the

pins are aligned and the connector locks in (it will
click).

For those using a musical instrument, insert the 1/4
inch plug on the other end of the MI33A Instrument
Cable into the appropriate jack on your your musi­cal instrument.

3) Mute the main sound system and rotate the AUDIO
LEVEL control on the transmitter to maximum
counterclockwise (Off).

Modulation LED Signal Level Chart

Signal Level -20 LED -10 LED

Attention: During the procedure to set the
compatibility mode, each step between toggles
of the power switch must be performed within
ten seconds, or the procedure must be started
from the beginning.

Less than -20 dB Off Off

-20 dB to -10 dB Green Off

-10 dB to +0 dB Green Green

+0 dB to +10 dB Red Green

Greater than +10 dB Red Red

LECTROSONICS, INC. 8

Frequency-Agile UHF Belt-Pack Transmitter

Adjusting the Transmitter Frequency

MIC input jack

AUDIO LEVEL

Control

-20 LED

-10 LED

4) Set the transmitter Power ON/OFF switch to ON.

5) For microphone users, position the microphone in

the location where it will be used in actual opera­tion.

For musicians, adjust the instrument volume
controls to the highest levels that would be used
during a performance.

6) For microphone users, observe the Modulation
LEDs while speaking or singing at the same voice
level that will be used during the program. Gradu­ally rotate the AUDIO LEVEL control clockwise until
the -10 LED glows green and the -20 dB glows
green with occasional red flickers. This indicates
full modulation and is the optimum setting for the
transmitter’s gain.

For musicians, gradually rotate the AUDIO LEVEL
control clockwise while playing the loudest notes
that will be played during the performance. Al­though the optimum setting is for both Modulation
LEDs to glow green, it is ideal for the -20 LED to
briefly flicker red during the loudest passages.

The AUDIO LEVEL control should be close to the
9:00 position for optimum audio quality with mini­mum distortion.

7) Once the transmitter’s audio gain has been set, the
remaining components of the audio system can be
energized and adjusted.

Warning: DO NOT use the audio level control
for controlling the volume of your sound
system or recorder levels. This gain
adjustment matches the transmitter gain with
the user’s voice level and microphone
positioning, or instrument output.

Frequency Select Switches

1.6M 100K

0

1

F

2

E

3

D

C

4

5

B

6

A

9

7

8

0

1

F

2

E

3

D

C

4

5

B

6

A

9

7

8

If you are experiencing interference from another signal
on your operating frequency, you may need to change
the operating frequency of your system. This is done
through two Frequency Select Switches located on the
left side of the transmitter case. (See Frequency Select
Switch Locations.)

The left switch adjusts the operating frequency of the
transmitter up or down in 1.6 MHz steps. The right
switch adjusts the operating frequency of the transmitter
up or down in 100 kHz steps. It is suggested to use the
metering on the associated receiver to find a clear
channel. Turn the transmitter off and leave the receiver
turned on.

All 400 Series (and a number of earlier receivers) offer
front panel LCDs that indicate the correct transmitter
switch settings, and built in scanning functions to help
locate clear channels. Use the scanning functions on
these receivers to find a clear channel, then switch both
the receiver and transmitter to the Frequency Select
Switch settings indicated in the receiver’s display.

The R400 Series receivers have an autotune function
(SmartTune) that automatically locates clear operating
channels.

If your receiver does not have an autotune or built in
scanning function, manually tune the receiver across its
band and find a frequency where little or no RF activity
is displayed.

After finding a clear channel, set the transmitter to this
new frequency, then turn it on and make sure the RF
signal is strongly indicated at the receiver. Be sure the
switch settings between the receiver and transmitter are
set exactly the same. If, for example, the 100K switch is
one click above or below the desired frequency, the
receiver will indicate RF, but no audio (or severely
distorted audio) will be produced.

Rio Rancho, NM 9

LM/IM

5-Pin Input Jack Wiring

Note: This section does not apply to the IM
transmitter when used as part of the IS400
Instrument System. The cable supplied with the
IS400 Insturment System is prewired and cannot
be field modified. The cable is available in two
configurations, MI33ARA (right angle) and
MI33AST (straight).

The wiring diagrams shown in Wiring Hookups For
Different Sources represent the basic wiring configura­tions necessary for the most common types of micro­phones and other audio inputs. Some microphones
may require extra jumpers or a slight variation in the
diagrams shown.

It’s virtually impossible to keep completely up to date on
changes that other manufacturers make to their prod­ucts. It is possible that you may encounter a micro­phone that differs from those illustrated. If this occurs
please visit our website and select the
quick link, or call our toll-free number listed in the back
of this manual for assistance.

When used on a wireless transmitter, the microphone
element is in the proximity of the RF coming from the
transmitter. The nature of electret microphones makes
them sensitive to RF, which can cause problems with
the microphone/transmitter compatibility. If the electret
microphone is not designed properly for use with
wireless transmitters, it may be necessary to install a
chip capacitor in the mic capsule or connector to block
the RF from entering the electret capsule. (See RF
Bypassing.) Obviously, RF bypassing is not a problem
when using the IM transmitter with the IS400 Instru­ment System.

PIN 1 - Shield (ground) for
positive biased electret lavalliere
microphones. For the increas­ingly rare negative biased
electret lavalliere microphones, it
is the bias voltage source. It is
also the shield (ground) for
dynamic microphones and line
level inputs.

PIN 2 - Shield (ground) for
negative biased electret lavaliere
microphones. Bias voltage
source for positive biased electret lavaliere micro­phones.

PIN 3 - Low impedance microphone level input for
dynamic microphones. Also accepts hand-held
electret microphones that have their own battery or
power supply.

PIN 4 - 4 k Ohm source load for non-Lectrosonics
electret microphones. Use in conjunction with other
pins to provide attenuation of high level input
signals.

PIN 5 - 40 k high impedance, line level input for
tape decks, mixer outputs, musical instruments, etc.

Mic Wiring Info

LECTROSONICS

4

3

5

2

1

TRANSMITTER

INPUT JACK

Input Circuit

RF Bypassing

Some mics require RF protection to keep the transmit­ter signal from affecting the capsule, even though the
transmitter input circuitry is already RF bypassed (see
5-Pin Input Jack Wiring schematic diagram above).

If the mic is wired as directed, and you are having
difficulty with squealing, high noise, or poor frequency
response, RF is likely to be the cause.

The best RF protection is accomplished by installing
330 pF bypass capacitors at the mic capsule. If this is
not possible, or if you are still having problems, capaci­tors can be installed on the mic wires inside the TA5F
connector housing.

The 330 pF capacitors are available from Lectrosonics.
Please specify the part number for the desired lead
style.

Leaded capacitors: P/N 15117
Leadless capacitors: P/N SCC330P

Note: The Lectrosonics M150 lavaliere mic is
already bypassed correctly for use with the LM or
IM transmitters.

2 WIRE MIC 3 WIRE MIC

CAPSULE

Preferred locations for bypass capacitors

SHIELD

AUDIO

TA5F

CONNECTOR

Alternate locations for bypass capacitors

CAPSULE

SHIELD

AUDI O

BIAS

TA5 F

CONNECTOR

LECTROSONICS, INC. 10

Line Level Signals

Note: This section does not apply to the IM
transmitter when used as part of the IS400
Instrument System.

The normal hookup for line level signals provides 40 dB
of attenuation allowing signal levels up to 3 V to be
applied without limiting. The normal hookup configura­tion can be modified for situations that require higher
levels of headroom, or lower levels of attenuation. (See
illustration below.)

Normal hookup configuration connects the Signal Hot
(Audio) to pin 5, Signal Gnd (Shield) to pin 1, and both
pins 3 and 4 jumped to pin 1.

If even more headroom is required, insert a 100 k
resistor in series with pin 5 (Audio). Put this resistor
inside the TA5F connector to minimize noise pickup.

For situations where lower than normal line levels (less
than 1 V) are expected, use the Lower Line Level Hook
Up: Signal Hot (Audio) to pin 5, Signal Gnd (Shield) to
pin 1, and pin 4 jumpered to pin 1. This configuration
provides 20 dB attenuati on to the input signal.

Frequency-Agile UHF Belt-Pack Transmitter

AUDI O

PIN

PIN

PIN

1

2

3

4

5

1

2

3

4

5

1

2

3

4

5

4

3

TA 5F

PLUG

4

3

TA 5F

PLUG

4

3

TA 5F

PLUG

1

5

2

1

5

2

1

5

2

Normal Hookup

More Headroom

Lower Line Level

Hookup

SHIELD (GND)

AUDI O

SHIELD (GND)

100k

SHIELD (GND)

AUDI O

Wiring Hookups for Different Sources

PIN

PIN

PIN

1

2

3

4

5

1

2

3

4

5

1

2

3

4

5

4

3

TA5F

PLUG

4

3

TA5F

PLUG

4

3

TA5F

PLUG

1

5

2

1

5

2

1

5

2

3 WIRE ELECTRET MIC

POSITIVE BIAS

2 WIRE ELECTRET MIC

POSITIVE BIAS

3 WIRE ELECTRET MIC

NEGATIVE BIAS

SHIELD

BIAS

AUDIO

SHIELD

AUDIO

SHIELD

BIAS

AUDIO

Wiring Diagram for MI33A Instrument Cable

The MI33ARA and MI33AST instrument cable assem­blies allow an optimum match between musical instru­ment pickups and Lectrosonics transmitters with 5-pin
input connectors.

The active preamp and low noise wire cable provide a
“same as wire” experience in a wireless environment.

The 30 inch long cable offers enough cable to comfort­ably link the instrument to the wireless transmitter
without being excessive.

SHIELD

2 WIRE ELECTRET MIC

AUDIO

NEGATIVE BIAS

SLEEVE

TIP

SHIELD

AUDIO

LINE LEVEL

RCA or 1/4 " PLUG

PIN

1

2

DYNAMIC

MIC LEVEL

1/4 " PLUG

Note: This cable is prewired and cannot be field
modified. The cable is available in two

1

2

3

3

Dynamic LO Z mic or electret with
manufacturer’s power supply.

SLEEVE

AUDIO

TIP

SHIELD

SHIELD

Preamp

PIN

PIN

PIN

SHIELD

PWR

AUDI O

3 k

1

2

3

4

5

1

2

3

4

5

1

2

3

4

5

PIN

configurations, MI33ARA (right angle) and
MI33AST (straight).

1

2

3

4

5

4

3

TA 5F

PLUG

4

3

TA 5F

PLUG

4

3

TA 5F

PLUG

5

5

5

4

3

TA 5F

PLUG

1

2

1

2

1

2

1

5

2

Rio Rancho, NM 11

LM/IM

Troubleshooting

It is important that you follow these steps in the sequence listed.

Symptom: Possible Cause:

Transmitter Battery LED off 1. Battery is inserted backwards.

2. Battery is dead.

No Transmitter Modulation LEDs 1. Gain control turned all the way down.

2. Battery is in backwards. Check power LED.

3. Mic capsule is damaged or malfunctioning.

4. Mic cable damaged or miswired.

5. Instrument Cable damaged or not plugged in.

6. Musical instrument volume control set to low.

Receiver Indicates RF But No Audio 1. Ensure that the transmitter and receiver Frequency Select

Switches are set to the same frequency.

2. Make sure the compatibility mode is the same on transmitter
and receiver.

3. Ensure musical instrument volume control is not set to minimum.

Receiver RF Indicator Off 1. Transmitter not turned on, or battery is dead.

No Sound (Or Low Sound Level), Receiver Indicates Proper Audio Modulation

Distorted Sound 1. Transmitter gain (audio level) is too high. Check Modulation

Wind Noise or Breath “Pops’” 1. Reposition microphone, or use a larger windscreen, or both.

2. Receiver antenna missing or improperly positioned.

3. Transmitter and receiver not on same frequency.
Check switches/display on transmitter and receiver.

4. Operating distance is too great.

1. Receiver output level set too low.

2. Receiver output is disconnected; cable is defective or miswired.

3. Sound system or recorder input is turned down.

LEDs on transmitter and receiver as transmitter is being used.
(Refer to ATTACHING A MICROPHONE OR MUSICAL
INSTRUMENT AND ADJUSTING AUDIO LEVELS.)

2. Receiver output may be mismatched with the sound
system or recorder input. Adjust output level on receiver to the
correct level for the recorder, mixer or sound system.

3. Transmitter is not set to same frequency as receiver. Check that
frequency select switches on receiver and transmitter match.

4. RF interference. Reset both transmitter and receiver to a clear
channel.

Hiss and Noise -- Audible Dropouts 1. Transmitter gain (audio level) far too low.

Excessive Feedback (With Mic) 1. Transmitter gain (audio level) too high. Check gain adjustment

2. Receiver antenna missing or obstructed.

3. Operating distance too great.

4. RF interference. Reset both transmitter and receiver to a clear
channel.

5. Musical instrument volume set too low.

and/or reduce receiver output level.

2. Transmitter too close to speaker system.

3. Mic is too far from user’s mouth.

LECTROSONICS, INC. 12

Specifications and Features

Frequency-Agile UHF Belt-Pack Transmitter

Operating frequencies: Block 21 537.600 - 563.100

Frequency Selection: 256 frequencies in 100 kHz steps
Channel Separation: 100 kHz
RF Power output: Greater than 50 mW
Pilot tone: 25 to 32 kHz frequency; 5 kHz deviation (400 Series only)
Frequency stability: ± 0.002%
Deviation: ± 75 kHz max. (400 Series only)
Spurious radiation: 60 dB below carrier
Equivalent input noise: –120 dBV, A-weighted
Input level: Nominal 2 mV to 300 mV, before limiting.

Input impedance: 2k Ohm
Input limiter: Dual envelope, >30 dB range

(Note: The dual envelope “soft” limiter provides exceptionally good handling of transients using variable attack and release time constraints.)

Gain control range: 43 dB; semi-log rotary control
Modulation indicators: Dual bicolor LEDs indicate modulation of -20, -10, 0, +10 dB referenced to full modulation.
Low frequency roll-off: LM: –12 dB/octave; 70Hz

Audio frequency response
(overall system): LM: 90 Hz to 20 kHz (+/- 1 dB) with the 70Hz low frequency roll-off filter.

(Note: The transmitter is deliberately rolled off at 70Hz in the LM tramsmitter to reduce transmission of the lower frequency noise.)

Controls: 2 position “OFF-ON” slide switch for noiseless turn on/turn off operation.

Audio Input Jack: Switchcraft 5 pin locking (TA5F)
Antenna: Galvanized steel, flexible wire.
Battery: Precision compartment auto-adjusts to accept any known alkaline 9 volt battery.
Battery Life: 6 hours (alkaline); 13 hours continuous (lithium)
Weight: 6.3 ozs. including battery
Dimensions: 3.1 x 2.4 x .75 inches

Block 22 563.200 - 588.700
Block 23 588.800 - 607.900 and 614.100 - 614.300
Block 24 614.400 - 639.900
Block 25 640.000 - 665.500
Block 26 665.600 - 691.100
Block 27 691.200 - 716.700
Block 28 716.800 - 742.300
Block 29 742.400 - 767.900

Greater than 1V maximum, with limiting.

IM: –12 dB/octave; 35Hz

IM: 40 Hz to 20 kHz (+/- 1 dB)

Front panel audio gain control.
Rotary switches on side panel adjust transmitter frequency.

Emission Designator: 180KF3E

Specifications subject to change without notice.

The FCC requires that the following statement be included in this manual:

This device complies with FCC radiation exposure limits as set forth for an uncontrolled environment. This device
should be installed and operated so that its antenna(s) are not co-located or operating in conjunction with any
other antenna or transmitter.

Rio Rancho, NM 13

LM/IM

Service and Repair

If your system malfunctions, you should attempt to correct or isolate the trouble before concluding that the equipment
needs repair. Make sure you have followed the setup procedure and operating instructions. Check the interconnect­ing cables and then go through the TROUBLESHOOTING section in this manual.

We strongly recommend that you do not try to repair the equipment yourself and do not have the local repair shop
attempt anything other than the simplest repair. If the repair is more complicated than a broken wire or loose connec­tion, send the unit to the factory for repair and service. Don’t attempt to adjust any controls inside the units. Once set
at the factory, the various controls and trimmers do not drift with age or vibration and never require readjustment.
There are no adjustments inside that will make a malfunctioning unit start working.

LECTROSONICS’ Service Department is equipped and staffed to quickly repair your equipment. In warranty repairs
are made at no charge in accordance with the terms of the warranty. Out-of-warranty repairs are charged at a modest
flat rate plus parts and shipping. Since it takes almost as much time and effort to determine what is wrong as it does
to make the repair, there is a charge for an exact quotation. We will be happy to quote approximate charges by phone
for out-of-warranty repairs.

Returning Units for Repair

For timely service, please follow the steps below:

A. DO NOT return equipment to the factory for repair without first contacting us by letter or by phone. We need to

know the nature of the problem, the model number and the serial number of the equipment. We also need a
phone number where you can be reached 8 A.M. to 4 P.M. (U.S. Mountain Standard Time).

B. After receiving your request, we will issue you a return authorization number (R.A.). This number will help speed

your repair through our receiving and repair departments. The return authorization number must be clearly shown
on the outside of the shipping container.

C. Pack the equipment carefully and ship to us, shipping costs prepaid. If necessary, we can provide you with the

proper packing materials. UPS is usually the best way to ship the units. Heavy units should be “double-boxed” for
safe transport.

D. We also strongly recommend that you insure the equipment, since we cannot be responsible for loss of or dam-

age to equipment that you ship. Of course, we insure the equipment when we ship it back to you.

Mailing address: Shipping address: Telephone:

Lectrosonics, Inc. Lectrosonics, Inc. [phone]
PO Box 15900 581 Laser Rd. [phone] Toll-free
Rio Rancho, NM 87174 Rio Rancho, NM 87124 [phone] Fax
USA USA

Web: E-mail:

www.lectrosonics.com [e-mail]

LECTROSONICS, INC. 14

Frequency-Agile UHF Belt-Pack Transmitter

Rio Rancho, NM 15

LIMITED ONE YEAR WARRANTY

The equipment is warranted for one year from date of purchase against defects in
materials or workmanship provided it was purchased from an authorized dealer. This
warranty does not cover equipment which has been abused or damaged by careless
handling or shipping. This warranty does not apply to used or demonstrator equipment.

Should any defect develop, Lectrosonics, Inc. will, at our option, repair or replace any
defective parts without charge for either parts or labor. If Lectrosonics, Inc. cannot
correct the defect in your equipment, it will be replaced at no charge with a similar new
item. Lectrosonics, Inc. will pay for the cost of returning your equipment to you.

This warranty applies only to items returned to Lectrosonics, Inc. or an authorized
dealer, shipping costs prepaid, within one year from the date of purchase.

This Limited Warranty is governed by the laws of the State of New Mexico. It states the
entire liablility of Lectrosonics Inc. and the entire remedy of the purchaser for any
breach of warranty as outlined above. NEITHER LECTROSONICS, INC. NOR
ANYONE INVOLVED IN THE PRODUCTION OR DELIVERY OF THE EQUIPMENT
SHALL BE LIABLE FOR ANY INDIRECT, SPECIAL, PUNITIVE, CONSEQUENTIAL,
OR INCIDENTAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
THIS EQUIPMENT EVEN IF LECTROSONICS, INC. HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES. IN NO EVENT SHALL THE LIABILITY OF
LECTROSONICS, INC. EXCEED THE PURCHASE PRICE OF ANY DEFECTIVE
EQUIPMENT.

This warranty gives you specific legal rights. You may have additional legal rights which
vary from state to state.

581 Laser Road NE • Rio Rancho, NM 87124 USA • www.lectrosonics.com
[phone] • [phone] • fax [phone] • [e-mail]

August 16, 2006