UM190
UHF BELT-PACK TRANSMITTER
OPERATING INSTRUCTIONS
and trouble-shooting guide
LECTROSONICS, INC.
Rio Rancho, NM
INTRODUCTION
Thank you for selecting the Lectrosonics UM190 belt-pack transmitter. The UM190 combines over 80 years of
engineering experience with the very latest components, in a design that addresses the most demanding
professional applications.
The design of the UM190 was the direct result of numerous conversations with users, staging and touring
companies and dealers across the US. The specific concerns and needs brought up in these conversations led
directly to the development of the operational features offered on the UM190. This is certainly not the first beltpack transmitter ever designed, but it is definitely the most thoroughly engineered unit available.
The UM190 is a rugged, machined aluminum package with a removable, spring loaded belt clip. The input section
provides a correct input tap for virtually any microphone or line level audio source. 5 Volts of bias voltage is
available to power electret mics with either positive or negative bias. Level indicating LEDs are provided on the
control panel to make level settings quick and accurate, without having to view the receiver. The battery
compartment accepts any 9 Volt alkaline battery and makes a positive connection via self-adjusting contacts. The
antenna is a detachable, locking 1/4 wavelength flexible wire that connects to a 50 Ohm port on the transmitter.
Only the UM190 transmitter is covered in this manual. Companion receivers are covered in separate manuals.
The UM190 will operate with any 190 Series Lectrosonics receiver on the same frequency.
TABLE OF CONTENTS
INTRODUCTION .......................................... 1
GENERAL TECHNICAL DESCRIPTION .......................... 2
CONTROLS AND FUNCTIONS ................................ 4
BATTERY INSTALLATION ................................... 6
OPERATING INSTRUCTIONS ................................. 7
OPERATING NOTES ....................................... 7
UM190 INPUT JACK WIRING ................................. 8
TROUBLESHOOTING ....................................... 9
SPECIFICATIONS AND FEATURES ............................ 10
SERVICE AND REPAIR ..................................... 11
RETURNING UNITS FOR REPAIR ............................. 11
WARRANTY ........................................ Back cover
The UM190 transmitter is FCC type accepted under Part 74: 470-608 MHz
1
GENERAL TECHNICAL DESCRIPTION
MIC
+5V BIAS
JACK
Vref
BASS
TREBLE
LP FILTER
HP FILTER
SET
LED
LIMIT
LED
COMPANDOR
Vreg
Vreg
+5VDC
+3.6VDC
COMPANDED
AUDIO
XTAL OSC
X4
X2 X2 X2
UHF TRANSMITTE R
+9VDC
PWR
LED
SHUNT
LIMITER
-9V
ONMUTE
OFF
SUPPLY
INPUT
AMP
AUDIO
LEVEL
LP
FILTER
PEAK AUDIO
INDICATOR &
LIMITER
DRIVER
X2
The UM190 transmitter is comprised of a number of functional sub-systems as shown in the block diagram below.
The 190 system uses 15kHz deviation. The transmitter circuits are all regulated to allow full output power from the
beginning (9 Volts) to the end (7 Volts) of battery life. The oscillator crystal is shock mounted to provide
ruggedness. The input amplifier uses a Motorola 33078 op amp for ultra low noise operation. It is gain controlled
with a wide range input compressor which cleanly limits input signal peaks over 30dB above full modulation.
Traditionally, compandors have been a source of distortion in wireless microphone systems. The basic problem
with conventional systems is that the attack and decay times are always a compromise. If the time constants are
fast, high frequency transients will not be distorted, but this will cause low frequency distortion. If the time
constants are slower, low frequency audio distortion will be low, but high frequency transients will then be distorted.
The 190 system introduces an entirely new approach to solving this basic problem, called "dual-band companding."
There are actually two separate compandors in the 190 system, one for high frequencies and one for low
frequencies. A crossover network separates the frequency bands at 1kHz with a 6dB per octave slope, followed by
separate high and low frequency compandors. The attack and release times in the high frequency compandor are
fast enough to keep high frequency transient distortion at a low level, and the low frequency compandor uses
slower time constants, reducing low frequency distortion to well below that of a conventional compandor.
Figure 1 - UM190 Block Diagram
High efficiency circuits throughout the design allow over 7 hours of operation using a single 9 Volt alkaline battery.
The battery compartment is a unique mechanical design which automatically adjusts to fit any brand alkaline
battery. The battery contacts are spring loaded to prevent "rattle" as the unit is handled.
The UHF transmitter section uses a crystal stabilized main oscillator followed by a quadrupler and three doubler
stages. The crystal controlled frequency is extremely stable over a wide temperature range and over time. Double
tuning used in the multiplier stages provides higher attenuation of spurious emissions which, in turn, minimizes the
2
possibility that the transmitter RF output would interfere with another transmitter/receiver system operating in the
same vicinity.
At UHF frequencies, where wavelengths and antennas are shorter than VHF, a resonant dangling wire is preferred.
The antenna on the UHF version of the UM190 consists of a flexible ¼ wavelength wire, detachable via a twist lock
connector. The impedance of this connector is 50 Ohms at UHF frequencies.
CONTROLS AND FUNCTIONS
LECTROSONICS
UM190
ON
MUTE
OFF
LEVEL
LIMIT
MIC LEVEL
LF
ROLL-OFF
ADJ
30Hz
150Hz
Figure 2 - M190 Controls and Functions
INPUT JACK
The input on the UM190 accommodates virtually every lavalier, hand-held or shotgun microphone available. Use a
Switchcraft TA5F connector on the cord. See the separate sheet titled "UM190 Input Jack Configuration"
regarding the correct connections for various microphones, and other sources.
ON/MUTE/OFF SWITCH
Turns the battery power on and off. The center position is an "audio mute" which should be used when setting the
MIC LEVEL control to turn off the sound from the microphone during this adjustment. Even when the switch is
turned off or on aburptly, the pilot tone muting system prevents "thumps" or transients from occurring.
"ON" LAMP
Glows brightly when the battery is good. A weak or dim lamp means that the battery is weak, and has about half
an hour of operation left. If the lamp fails to light, the battery should be replaced. The power lamp should light up
in both the "MUTE" and "ON" positions of the POWER/MUTE SWITCH.
The "ON" lamp is connected to a precision battery test circuit that continuously monitors battery voltage. The LED
is at full brightness with a new 9 Volt alkaline battery. As the battery voltage drops during use, the LED brightness
will also decrease. After about 7 hours the battery voltage will be about 7 Volts and the LED will be completely out.
3
CONTROLS AND FUNCTIONS (cont’d)
50 Ohm
Antenna Port
Since the internal circuits are all tightly regulated and the RF output stage has a separate discrete regulator, the
transmitter will continue to operate to a battery voltage of 6.5 Volts. From 6.5 Volts to 6 Volts, the transmitter will
still operate, but with degraded performance. Please note that a weak battery will sometimes light the POWER
LED immediately after turn on, but will soon discharge to the point where the LED will go out, just like a flashlight
with "dead" batteries.
The combination of an accurate battery condition indicator and regulation of all internal circuits provides much
longer battery life, as well as consistent performance over the life of the battery.
MODULATION LEDS
Indicate the proper setting of the MIC LEVEL control.
LEVEL LED -- Flickers or glows when sufficient audio is present.
LIMIT LED -- Lights up when the input level is high enough to cause limiting. The input limiter has a very
high overload threshold (over 40 dB). Generally speaking, some limiting is desirable in normal operation to
improve the signal to noise ratio of the system. The limiting action is not audible and does not create
distortion. A highly trained ear would hear only the compression of the peaks in the audio signal, which is
desirable with most tape recorders and many sound reinforcement systems.
MIC LEVEL
Used to adjust the audio input level for the proper modulation.
ANTENNA
The flexible wire antenna supplied with the UM190 UHF transmitter is cut to 1/4 wavelength. It is removable via a
twist lock connector. The 50 Ohm RF port can also be connected directly to test equipment.
ADJUSTABLE LOW FREQUENCY ROLL-OFF
A 6dB/octave low frequency roll-off is provided in the audio section, with the -3dB point adjustable
from 30Hz to 150Hz.
THE BELT CLIP
The belt clip may be removed for special applications by removing one screw.
USE ONLY THE SCREW THAT IS SUPPLIED
The circuitry is tightly packed into this unit. A longer screw will permanently damage the transmitter!
Figure 3 - UM190, UHF Antenna Location
4
BATTERY INSTALLATION
The transmitter is powered by a standard alkaline 9 Volt battery. It is important that you use ONLY an ALKALINE
battery for longest life. Standard zinc-carbon batteries marked "heavy-duty" or "long-lasting" are not adequate.
Ni-cad rechargeable batteries will only provide 2 hours of operation, or less, and will run down quite abruptly.
Alkaline batteries provide over 7 hours of operation. The battery status circuitry is designed for the voltage drop
over the life of alkaline batteries.
To open the battery compartment, press outward on the cover door in the direction of the arrow as shown in the
drawing. Only firm, sliding pressure is needed to open and close the battery door. Swing the door open 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.
Swing the
Press outward on the
battery door in this
direction
door open
Figure 4 - M190 Battery Compartment Door
Insert the battery correctly and close the cover by pressing the door closed and across, reversing the opening
procedure illustrated above. If the battery is inserted incorrectly, the door will not close. Do not force the door
closed.
5
OPERATING INSTRUCTIONS
1) Install a fresh battery according to the instructions on the previous page.
2) Insert the microphone plug into the input jack, aligning the pins; be sure that the connector locks in.
3) Attach the antenna to the jack on the bottom of the unit. Be sure it is screwed in firmly.
If you have used our VHF transmitters before, you will notice that they use the
shield of the microphone cord as the antenna. The UM190 UHF transmitter
uses a separate 1/4 wave flexible wire as the antenna. If the antenna is not
attached, the transmitter will not radiate.
3) Turn the power switch to the "MUTE" position on the transmitter.
4) Position the microphone in the location you will use in actual operation.
5) While speaking or singing at the same voice level that will be actually used, observe the MOD LEVEL
LEDs. Adjust the MIC LEVEL control knob until the LEDs begin to light. Start at a low setting where
neither LED lights as you speak. Gradually, turn the gain up until one LED lights, then the other.
The LEVEL LED lights when the audio level is about 12dB below full modulation. The LIMIT LED lights
when the limiter begins to operate. There is over 40dB of limiting range without overload above the LIMIT
LED, so it is normal that the LIMIT LED light up 5% to 10% of the time during use.
6) Once the gain has been adjusted, the transmitter audio can be turned on to make sound system level
adjustments. Move the power switch from the MUTE to the ON position and adjust the receiver and/or
sound system level as required.
OPERATING NOTES
The MIC LEVEL control knob should not be used to control 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.
If the mic level is too high -- both LEDs will light frequently or stay lit. This condition may reduce the dynamic
range of the audio signal.
If the mic level is too low -- neither LED will light, or the LEVEL LED will light dimly. This condition may cause hiss
and noise in the audio.
The first LED turns on 12dB below full deviation. The limiting LED turns on at full deviation and indicates that the
input shunt compressor is operating. The input limiter will handle peaks over 40dB above full modulation,
regardless of the gain control setting. The limiter uses a true absolute value circuit to detect both positive and
negative peaks. The attack time is 5 milliseconds and the release time is 200 milliseconds. Occasional limiting is
desirable, indicating that the gain is correctly set and the transmitter is fully modulated for optimum signal to noise
ratio.
Different voices will usually require different settings of the MIC 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.
6
UM190 INPUT JACK WIRING
5.1VDC
1K 1K
330
MPF480'S
7
22K
.22M
1uH
3.3M
10K
1K
5
33M
510
4
6
2
3
4
3
2
1
60NH
5321
1N
-
+
330PF
330PF
4
3
2
1
5
LECTROSONICS
+
+
+
Vcc
M 190
M190 TRANSMITTER
EQUIVALENT INPUT CIRCUIT
1 - NEG GND (OR BIAS)
2 - POS BIAS (OR GND)
3 - MIC
4 - SOURCE LOAD
5 - LINE IN
TO
AUDIO
CIRCUITS
MIC
GAIN
TO
LIMITER
CONTROL
LF
CUT
The wiring diagrams shown on the separate sheet represent the basic wiring necessary for the most common types
of microphones and other audio inputs. Some microphones may require extra jumpers or a slight variation on 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 these instructions. If this occurs please call
our toll-free number listed in the back of this instruction manual. Our service department can answer your
questions regarding microphone compatibility.
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. This modification is shown on the separate sheet titled "UM190 INPUT JACK
CONFIGURATION."
Our VHF transmitters uses the shield of the microphone cord as the antenna. The UM190 UHF transmitter uses a
1/4 wave flexible wire to radiate the RF signal. There is really not much difference between these two approaches,
with respect to the effect of the RF on the microphone capsule. Even in transmitters that utilize a "dangling wire,"
the microphone is still part of the "ground plane" and is therefore still in the antenna circuit.
Figure 5 - M190 Input Connector and Schematic
PIN 1 Shield (ground) for positive biased electret lavalier microphones. Bias voltage source for negative biased
electret lavalier microphones. Shield (ground) for dynamic microphones and line level inputs.
7
PIN 2 Shield (ground) for negative biased electret lavalier microphones. Bias voltage source for positive biased
electret lavalier microphones.
PIN 3 Low impedance microphone level input for dynamic microphones. Also accepts hand-held electret
microphones provided the microphone has its own built-in battery.
PIN 4 1K Ohm source load for non-Lectrosonics electret microphones. Use in conjunction with other pins to
provide attenuation of high level input signals.
PIN 5 High impedance, line level input for tape decks, mixer outputs, musical instruments, etc.
TROUBLESHOOTING
Before going through the following chart, be sure that you have a good battery in the transmitter. 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 mis-wired.
RECEIVER RF LAMP OFF 1) Transmitter not turned on.
2) Transmitter battery is dead.
3) Receiver antenna missing or improperly positioned.
4) Transmitter and receiver not on same frequency. Check
labels on transmitter and receiver.
5) Operating range is too great.
6) Transmitter antenna not connected
NO SOUND (OR LOW SOUND LEVEL),
AND RECEIVER MOD LEVEL LEDs ARE OFF 1) Transmitter audio muted. Make sure transmitter
power/mute switch is in the "ON" position.
2) Transmitter mic gain set too low.
3) Defective microphone or cord.
NO SOUND (OR LOW SOUND LEVEL),
RECEIVER MOD LEVEL LEDs ARE ON 1) Receiver output level set too low.
2) Receiver output is disconnected; cable is defective or
mis-wired.
3) Sound system or recorder input is turned down.
DISTORTED SOUND 1)Transmitter gain (audio level) is far too high. Check mod
level lamps on transmitter and receiver as it is being
used. (refer to page 6 for details on gain adjustment)
2) Receiver output may be mis-matched with the sound
system or recorder input. Adjust output level on receiver
to the correct level for the recorder, mixer or sound
system.
3) Excessive wind noise or breath "pops." Re-position
microphone and/or use a larger windscreen.
HISS AND NOISE - AUDIBLE DROPOUTS 1) Transmitter gain (audio level) far too low.
2) Receiver antenna missing or obstructed.
3) Transmitter antenna missing.
4) Operating range too great.
EXCESSIVE FEEDBACK 1) Transmitter gain (audio level) too high. Check gain
adjustment and/or reduce receiver output level.
2) Transmitter too close to speaker system.
3) Mic is too far from user’s mouth.
8
SPECIFICATIONS AND FEATURES
Operating frequencies: 470 to 608 MHz
RF Power output: 100 mW (nominal)
Frequency stability: ±0.002%
Deviation: ±15 kHz (max)
Preemphasis: shelving type, 100us (1.6kHz), 24us (6.4kHz)
Spurious radiation: 50 dB below carrier
Equivalent input noise: -126 dBV
Input level: Nominal 2 mV to 300 mV, before limiting.
Greater than 50 Volts maximum, with limiting.
Input impedance: Taps provided for 500, 1k, 10k Ohm
Input compressor: Soft compressor, >40 dB range
Gain control range: 43 dB; semi-log rotary control
Modulation indicators: Dual LEDs indicate modulation level 12 dB below limiting and at
the onset of limiting.
Controls: 3 position "OFF-MUTE-ON" slide switch for noiseless turn
on/turn off operation. Front panel knob adjusts audio gain.
Audio Input Jack: Switchcraft 5 pin locking (TA5F)
Antenna: Detachable, flexible wire supplied. 50 Ohm port allows
connection to test equipment.
Battery: Precision compartment auto-adjusts to accept any known
alkaline 9 Volt battery. (We’ve tried 108 different ones!)
Battery Life: 7.5 Hours with alkaline 9 Volt
Weight: 6.3 ozs. including battery
Dimensions: 3.1 x 2.4 x .75 inches
Emission Designator: 35KF3E
The UM190 transmitter is FCC type accepted under Part 74: 470-608 MHz
9
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 out
the inter-connecting cords and then go through the TROUBLESHOOTING section in the 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
You will save yourself time and trouble if you will 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 am to 4 pm (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
damage to equipment that you ship. Of course, we insure the equipment when we ship it back to you.
Mailing address: Shipping address: Telephones:
Lectrosonics, Inc. Lectrosonics, Inc. (505) 892-4501
PO Box 15900 581 Laser Rd. (800) 821-1121
Rio Rancho, NM 87174 Rio Rancho, NM 87124 FAX: (505) 892-6243
USA USA
World Wide Web: http://www.lectrosonics.com email: sales@lectrosonics.com
10
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, we will, at our option, repair or replace any
defective parts without charge for either parts or labor. If we cannot correct the
defect in your equipment, we will replace it at no charge with a similar new item.
We will pay for the cost of returning your merchandise to you.
This warranty applies only to items returned to us, shipping costs prepaid, within
one year from the date of purchase.
This warranty gives you specific legal rights. You may have additional legal
rights which vary from state to state.
LECTROSONICS, INC.
581 LASER ROAD
RIO RANCHO, NM 87124 USA July 23, 1999
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