H187
VHF Narrowband Plug-On Transmitter
INSTRUCTION MANUAL
• Crystal Controlled Fixed Frequency
• Wide Range Input Limiting
• Floating, Auto Latching Input Coupler
• Machined Aluminum Construction
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Serial Number:
Purchase Date:
Rio Rancho, NM, USA
www.lectrosonics.com
H187
The H187 transmitter is FCC type accepted under Part 90 (150-172 MHz), and Part 74 (174-216 MHz)
LECTROSONICS, INC.2
Plug-On Transmitter
Table of Contents
Introduction ............................................................................................................................................................................................3
General Technical Description .............................................................................................................................................................. 3
H187 Block Diagram............................................................................................................................................................................. 3
Controls and Functions .........................................................................................................................................................................4
Input Jack .............................................................................................................................................................................................4
Power/Mute Switch ...............................................................................................................................................................................4
Power On/Off LED ................................................................................................................................................................................4
Modulation LEDs ..................................................................................................................................................................................4
Level LED .............................................................................................................................................................................................4
Limit LED ..............................................................................................................................................................................................4
Mic Level .............................................................................................................................................................................................. 4
Operating Instructions ..........................................................................................................................................................................5
Battery Replacement ............................................................................................................................................................................. 6
Specifications and Features ................................................................................................................................................................. 6
Troubleshooting .....................................................................................................................................................................................7
Service and Repair .................................................................................................................................................................................8
Returning Units for Repair ....................................................................................................................................................................8
Rio Rancho, NM 3
H187
Introduction
Thank you for selecting Lectrosonics wireless. This
VHF transmitter is part of a family of narrowband
wireless components that have served the needs of
television broadcast and motion picture production
markets since 1988.
The H187 plug-on transmitter replaces earlier versions,
updating the design with surface mount PCB construction and the latest electronic components. The input
coupler has evolved since the first versions were
introduced, making it more rugged and better able to
adapt to the wide variety of different XLR connectors
General Technical Description
found on hand held and shotgun microphones.
The housing and external mechanical parts are constructed of machined aluminum to provide the ruggedness needed in field production. The battery door
remains attached to the housing when opened, and the
control panel is recessed to prevent damage from rough
handling. These and other features have been added
or modified since the first versions were introduced.
The H187 remains a workhorse in broadcast ENG,
continuing the Lectrosonics commitment to quality.
The H187 transmitter is comprised of four major
functional subsystems: the mic preamp/gain control, the
compandor, the compressor/limiter and the RF transmitter (see block diagram below).
The mic preamp is an ultra-low noise type op-amp.
Aside from gain control, this stage also adds high
frequency pre-emphasis to the audio signal. This
insures highest signal-to-noise ratios under varying
signal conditions. Gain control is semi-logarithmic to
provide smooth gain control action.
The compandor is a high quality audio device that
processes the input signal such that large dynamic
ranges of input signal can be transmitted to the receiver
without overload or noise. A complementary system in
the receiver recovers the original dynamics of the signal
for full audio quality. Compression and expansion ratios
are complementary at 2:1. High frequency pre-emphasis is implemented in the transmitter to provide another
10dB signal-to-noise ratio improvement. Matching deemphasis is provided in all receivers.
The compressor/limiter is a low distortion shunt FET
compressor. Control signals for the compressor are
derived after the compandor to eliminate any possibility
of overload under any signal condition up to a maximum
of 3 Volts input. The range of limiting action before
gross distortion occurs is 35dB.
The compandor in the 187 series transmitters is much
tighter than the 185 series. The H187 compandor will
hold the transmitter deviation to no more than ±15kHz
under all circumstances. The 185 compandor would
allow some excursions beyond 15kHz during strong
audio “spikes.”
The RF transmitter is composed of the crystal stabilized
main oscillator followed by a frequency tripler and two
frequency doublers. All three stages are double tuned.
Double tuning provides maximum attenuation of spurious signals, which in turn minimizes the possibility that
a transmitter would interfere with another transmitter/
receiver system on another frequency.
All RF stages are biased from a regulated internal
source. The output stage has a separate feedback
regulator which not only stabilizes its operating point,
but also minimizes AM distortion. These regulators
keep the RF performance consistent from the beginning
(9 Volts) to the end (6.5 Volts) of battery life.
Schematics and alignment instructions will be provided
to qualified repair personnel on request.
H187 Block Diagram
MIC LEVEL
XLR
INPUT
LIMITER
35 dB
MIC
PREAMP
LIMIT LED
LEVEL LED
COMPANDOR
+9V IN
15MHZ XTAL
OSCILLATOR
(VCO)
BATTERY
SENSOR
CIRCUIT
FREQ.
TRIPLER
POWER
LED
45MHZ
FREQ.
DOUBLER
VOLTAGE
REGULATOR
LECTROSONICS, INC.4
90MHZ
FREQ.
DOUBLER
FEEDBACK
REGULATOR
180
MHZ
RF
OUT
Controls and Functions
The H187 may be used with a wide variety of microphones. The 3-pin XLR type connector on the H187
allows the transmitter to be used with any dynamic
microphone, as well as many two wire positive bias
lavaliere systems (such as those systems supplied by
Lectrosonics.)
Input Jack
Standard 3-pin Switchcraft XLR type. Pin 2 is signal,
pin 3 is signal ground, and pin 1 is case ground (see
schematic below). The H187 is self-locking onto a
standard microphone. The XLR connector is permanently bonded to the metal collar, and is not normally
replaceable. The electret bias is 5 Volts at 1mA or less.
The bias is connected in a “phantom” manner and will
not interfere with any standard balanced microphone. If
severe noise is experienced when the microphone is
moved with respect to the H187, the cause is an
unbalanced condition between pins 2 and 3 of the
microphone.
1K
33UF
AUTO-LOCK
XLR INPUT
1 UH
12
3
1 UH
1 UH
1K
Input Jack Schematic
Power/Mute 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. The “mute” position disconnects the audio signal from the transmitter and allows
you to adjust the audio modulation level without the
possibility of feedback. When turning the transmitter
on, pause for a moment in the “mute” position. This will
prevent a turn-on surge from occurring (a “thump”
sound).
980
5.1V
TO MIC
PREAMP
+9 VOLTS
Plug-On Transmitter
The POWER LED 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.
As the battery voltage drops during use, the LED
brightness will also decrease. After 12 to 15 hours the
battery voltage will be about 7 Volts. The LED will be
completely extinguished. 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 soon will discharge to the point
where the LED will extinguish.
The combination of an accurate battery condition
indicator and regulation of all internal circuits guarantees much longer battery life, as well as consistent
performance versus battery life.
Modulation LEDs
Indicate the proper setting of the MIC LEVEL control.
Level LED
Flickers or glows all the time if the audio volume is
adequate for normal operation.
Limit LED
Lights up when the audio volume is high, indicating that
the signal level is being limited by the compressor.
Optimum signal-to-noise ratio is obtained when the limit
LED lights occasionally.
Mic Level
Used to adjust the audio input volume for the proper
modulation level. Rotate knob until the LEVEL LED
flickers when there is an input signal. The LIMIT LED
should light occasionally.
LEVEL LED
LIMIT LED
Power On/Off LED
Glows brightly when battery is good. A weak or dim
BATTERY
POWER
LED
LED means that the battery is weak, and has about an
hour of operation left. If the LED fails to light, the
battery should be replaced. The power LED should
light up in both the “mute” and “on” positions of the
POWER/MUTE SWITCH.
TOP VIEW
Rio Rancho, NM 5
LEVEL
CONTROL PANEL
OFF
MUTE
ON
H187
Operating Instructions
1) Insert the H187 into the selected microphone.
Listen for the “click” that indicates the H187 has
locked on to the microphone. Pull on the mic to
insure proper locking has occurred.
2) Turn the power switch to the “MUTE” position on
both the transmitter and the receiver. The “MUTE”
position allows internal voltages to stabilize before
audio signal paths are opened.
3) Hold the microphone as you will when you will be
using it.
4) Speak as loudly as you expect to speak in normal
system use. Rotate the MIC LEVEL knob so that
the LEVEL LED flickers or stays lit as you speak.
The LIMIT LED should light up on loud “peaks.”
Occasional lighting of the LIMIT LED (about 1015% of the time) indicates proper operation and
optimum signal-to-noise ratio.
transmitter is limiting, little distortion is produced
because of the high linearity of the gain control
circuit in the H187.
5) Move switches to “ON” position on both the transmitter and the receiver and adjust the volume of the
sound system.
Even when the
If the mic level is too high — the LIMIT LED will light
frequently or stay on. This condition may cause distortion.
If the mic level is too low — neither LED will light, or
the LEVEL LED will light dimly. This condition will
cause hiss and noise. You may experience severe
reduction in apparent range if the modulation level is
too low. It may sound as if you are getting dropouts.
What is actually happening is that you are hitting your
noise floor because the S/N ratio has been compromised by the low modulation.
The LEVEL LED turns on at -10dB below full deviation.
The LIMIT LED turns on at full deviation and indicates
that the input shunt compressor is operating. The input
compressor operates over a full 35dB range regardless
of the gain control setting. The compressor uses a true
absolute value circuit to detect both positive and
negative peaks. The attack time is 2 milliseconds and
the release time is 80 milliseconds. Occasional limiting
is desirable, indicating that the gain is correctly set and
the transmitter is fully modulated.
NOTE: The MIC LEVEL control should not be
used to control the volume of your sound system.
This is accomplished using the level control on the
receiver, or a level control on the mixing console.
TO ATTACH
Press firmly, listen for click.
Depress collor fully.
Pull on mic to insure locking.
Hold the transmitter
case and rotate the
collar in the direction
shown. Do this over
a soft surface as the
microphone may pop
off suddenly.
TO REMOVE
LECTROSONICS, INC.6
Battery Replacement
The H187 transmitter is powered by a standard alkaline
9 Volt battery. It is important that you use ONLY an
ALKALINE battery for longest life. Standard zinccarbon batteries marked “heavy duty” or “long-lasting”
are not adequate. They will provide only about 4 hours
of operation. Similarly, nicad rechargeable batteries
only give 4 hours of operation, and will also run down
quite abruptly. Alkaline batteries provide about 15
hours of operation.
To open the battery compartment, press outward on the
cover door in the direction of the arrow as shown in the
RELEASE
DOOR
SWING OPEN
Plug-On Transmitter
drawing. Only slight, 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. Insert the battery and close
the cover by pressing in and across, reversing the
opening procedure outlined above. Note that the
battery door will NOT close if the battery is inserted
incorrectly, since the terminals will hit a protective
polarity barrier.
OBSERVE
POLARITY
Specifications and Features
Operating frequencies: 150 to 216 MHz
RF Power output: 50mW
Deviation: ±15kHz
Spurious radiation: 55dB below carrier
Equivalent input noise: -126dBV
Input level: Nominal 2mV to 300mV (before compression)
Input impedance: 22k Ohms (compatible with all Lo-Z microphones)
Input compressor: Soft compressor, 35 dB range allows
Gain control range: 43dB; semi-log rotary control
Modulation indicators: Dual LEDs indicate modulation level and onset
Controls: 3 position “OFF-MUTE-ON” for noiseless operation;
Connector: 3-pin XLR type with auto-locking collar
Battery: Any 9 Volt alkaline battery
Weight: 7 ozs. including battery
Dimensions: 1.5 x 1.5 x 4.2 inches
Emission Designator: 54KOF3E
Specifications subject to change without notice.
3 Volt max. input
of limiting
rotary knob adjusts audio gain
Rio Rancho, NM 7
H187
Troubleshooting
Before going through the following chart, be sure that you have a good battery in the transmitter - the red power LED
on the transmitter panel should glow brightly.
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.
No Sound is Heard and 1) Transmitter not turned on.
Receiver Lamp is Off 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.
No Audio is Heard But Receiver 1) On/Off switch is in “mute” position
RF LED Is On receiver or transmitter.
2) Microphone on/off switch is in “off” position.
3) Volume is turned down or off on transmitter or receiver.
4) Receiver not properly connected to other audio equipment.
5) Transmitter POWER switch may be turned on and off (i.e. through
the mute position). A “thump” should be heard in the sound, again
indicating a properly functioning receiver.
NOTE: If the modulation level LEDs on the receiver are indicating properly, the problem is NOT in the transmitter.
No Sound and Receiver 1) Transmitter audio muted. Make sure front panel power
Mod Level LEDs Are Off switch is in the on position.
No Sound and Receiver 1) Receiver audio is muted. Refer to receiver manual.
Mod Level LEDs Are On 2) Receiver audio output is disconnected or cable is defective or
mis-wired.
3) Sound system or recorder input is turned down.
Noise (Hiss) is Heard Along 1) MIC LEVEL is too low.
With the Signal 2) Transmitter and receiver may be too far from one another.
3) Receiver antenna may be defective or disconnected.
Distorted Sound 1) MIC LEVEL is too high.
2) Mic may be distorting; try a different mic and listen again.
3) PA system may be overloading.
Excessive Feedback 1) Transmitter gain (audio level) too high.
Check gain adjustment and/or reduce receiver output level.
2) Microphone too close to speaker system.
3) Microphone too far from user’s mouth.
4) Sound system volume set too high.
LECTROSONICS, INC.8
Plug-On Transmitter
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. (505) 892-4501
PO Box 15900 581 Laser Rd. (800) 821-1121 Toll-free
Rio Rancho, NM 87174 Rio Rancho, NM 87124 (505) 892-6243 Fax
USA USA
Web: E-mail:
www.lectrosonics.com sales@lectrosonics.com
Rio Rancho, NM 9
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.
ld any defect develop, Lectrosonics, Inc. will, at our option, repair or replace any
Shou
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, s
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
PO
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.
hipping costs prepaid, within one year from the date of purchase.
SSIBILITY OF SUCH DAMAGES. IN NO EVENT SHALL THE LIABILITY OF
581 Laser Road NE • Rio Rancho, NM 87124 USA • www.lectrosonics.com
(505) 892-4501 • (800) 821-1121 • fax (505) 892-6243 • sales@lectrosonics.com
March 30, 2006
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