T187
VHF HAND-HELD TRANSMITTER
OPERATING INSTRUCTIONS
and trouble-shooting guide
LECTROSONICS, INC.
Rio Rancho, NM
INTRODUCTION
Thank you for selecting the Lectrosonics T187 hand-held wireless transmitter. The
T187 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 T187 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 T187. This is certainly not the first hand-held
transmitter ever designed, but it is definitely the most thoroughly engineered unit
available.
The T187 is an integral microphone/transmitter with an internal antenna. The
antenna is a dipole type utilizing the two printed circuit boards as the elements. The
housing is composed of durable PVC, machined to a natural, comfortable shape.
Internal mechanical parts are machined aluminum.
Only the T187 transmitter is covered in this manual. Companion receivers are
covered in separate manuals. The T187 will operate with any 185 Series Lectrosonics VHF receiver on the same frequency.
TABLE OF CONTENTS
INTRODUCTION .................................................................................................. 2
GENERAL TECHNICAL DESCRIPTION ............................................................ 3
CONTROLS AND FUNCTIONS .......................................................................... 4
BATTERY INSTALLATION ................................................................................... 7
OPERATING INSTRUCTIONS ............................................................................ 8
OPERATING NOTES ........................................................................................... 8
TROUBLESHOOTING ......................................................................................... 9
SERVICE AND REPAIR ..................................................................................... 10
RETURNING UNITS FOR REPAIR................................................................... 10
SPECIFICATIONS AND FEATURES ................................................................ 11
WARRANTY ......................................................................................... Back cover
The T187 wireless microphone is FCC type accepted under the following parts:
Part 90 (150-172 mHz) and Part 74 (174-216 mHz)
2
VHF Hand-held Transmitter
GENERAL TECHNICAL DESCRIPTION
The T187 transmitter is comprised of a number of functional sub-systems as shown in the block diagram below. It is
offered with a variety of popular dynamic and electret microphone capsules from Shure, Electro-Voice and others for
various applications.
The limiter is a low distortion shunt FET compressor operating before the mic preamp. Control signals for the
compressor are derived after the mic preamp to eliminate any possibility of overload under any signal input condition
up to a maximum of 30 Volts input. The range of limiting action before distortion occurs is 20 dB. Audio signal level
and compressor action are indicated by LEDs visible under the battery cover door, next to the gain control.
The mic preamp is an ultra-low noise NE5534 type op-amp. The gain control, accessed by removing the battery
door, is semi-logarithmic to provide smooth action. Aside from gain control, this stage also adds high frequency preemphasis to the audio signal, to provide a 10 dB signal-to-noise ratio improvement. The receiver provides matching
de-emphasis to insure the highest signal-to-noise ratios under varying RF signal conditions.
The T187 audio section includes a 2:1 compandor noise reduction circuit compatible with all Lectrosonics 185 Series
VHF receivers. This compandor compresses (“encodes”) the dynamic range by reducing it 2:1 in the transmitter
audio signal. Complementary circuitry in the receiver restores (“decodes”) the original full dynamic range of the
signal by expanding it 1:2.
There are two operating switches located on the bottom panel. One is for power on/off and the other is an audio
mute. These operating switches can be bypassed for applications where the user should not have access to them.
The RF transmitter section is composed of a crystal stabilized main oscillator followed by a frequency tripler and two
frequency doublers. The crystal controlled frequency is extremely stable over a wide temperature range and over
time. All three oscillator stages are double tuned. Double tuning provides higher attenuation of spurious emissions
which, in turn, minimizes the possibility that the transmitter RF output would interfere with another transmitter/
receiver system operating in the same vicinity.
All RF stages are biased from a regulated internal power supply. 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 and
audio performance consistent from the beginning (9 Volts) to the end (6.5 Volts) of battery life.
LIMIT
LED
MIC
CAPSULE
LIMITER
PRE
AMP
BATTERY
9 VOLT
-10dB
LED
COMPANDOR
+9V OUT
AUDIO
BYPASS
BYPASS
POWER
OSC.
(VXO)
+9V IN
TRIPLER
BATT
SENSOR
POWER
LED
ON/OFF
DOUBLER
VOLTAGE
REGULATOR
INTERNAL
ANTENNA
DOUBLER
FEEDBACK
REGULATOR
T187 Block Diagram
Rio Rancho, NM – USA
3
CONTROLS AND FUNCTIONS
EXTERNAL
“P” SWITCH -- POWER ON/OFF
A slide switch which turns battery power on and off. The LED next to the switch lights up when the
“P” switch is turned on. This LED also serves as a battery condition indicator. The LED will glow
brightly when the battery is good and will dim as the battery condition deteriorates. The LED is at
full brightness with a new battery. After 12 to 15 hours of operation the battery voltage will be about
7 Volts and the LED will be completely dark.
“A” SWITCH -- AUDIO ON/OFF
A slide switch which “mutes” the audio in the OFF position and allows the audio gain (modulation
level) of the transmitter to be adjusted without feedback from the sound system.
INTERNAL
MOD LEVEL LEDs
These LEDs indicate the audio input level and are used when adjusting the
transmitter AUDIO LEVEL (gain) control. As the audio level increases, first one
LED lights. The other LED lights as the audio level reaches maximum modulation. The LEDs are located underneath the battery cover, next to the AUDIO
LEVEL control.
AUDIO LEVEL
This knob (located underneath the battery door) is operated while speaking or
singing into the transmitter to adjust the audio gain of the T187 for the correct
amount of modulation. The LEDs located next to it indicate the modulation level as the gain is adjusted. See page 8
for details on this very important adjustment.
Audio Power
On/Off On/Off
Mod Level
LEDs
Gain Control
AUDIO
LEVEL
PA
EXTERNAL SWITCHES BYPASS
This concealed slide switch defeats the external switches on the bottom panel for
applications where it is best that the user not be able to operate the power and
mute switches.
EXTERNAL
EXTERNAL
LED
SWITCHES
OFF
BYPASS
Bypass Switches
EXTERNAL LED OFF
This slide switch defeats the battery status LED on the bottom panel for applications where the LED may be distracting. With this switch in the right-hand position, the power will remain on and the transmitter operating, even though
the power LED is off.
4
INTERNAL CONTROLS - SHURE SM87 VERSION
0
-10 dB
This switch enables an extra 10dB of audio attenuation for those rare times
when the Audio Level control is already at minimum and the mic is still overloading.
The 10dB attenuator should only be used as a last resort. Do not leave it
enabled when it is not needed.
To gain access to the switch, turn the windscreen counter-clockwise and remove
it. Slide the switch handle toward the -10dB label to activate the attenuator.
Factory default is NO attenuation.
VHF Hand-held Transmitter
INTERNAL CONTROLS - VARIMIC VERSION
Caution - Due to the high RF levels surrounding the transmitter, the sound of the
Varimic capsule may be temporarily affected if the metal windscreen is not in place.
Always make the final decision about sound balance and quality with the windscreen
in place.
The VariMic head includes adjustments for Bass, Midrange and Treble response. There is also an attenuation adjustment to provide up to 15dB of
additional headroom if needed.
BASS / MID / TREBLE
The bass and treble controls will boost/cut by up to approximately 8dB while
the Mid control will boost/cut up to about 6dB. These controls operate as
standard tone controls. Counter-clockwise will reduce the response in that
band and clockwise will provide a true boost. These controls can be accessed
by removing the windscreen. To remove the windscreen,
grasp the body of the transmitter in one hand and the
windscreen in the other hand. Carefully unscrew the
wind-screen counter-clockwise until it comes off then
carefully slide the windscreen past the mic element.
• Set flat, the mic capsule is very wide range and sounds
+10
+5
a lot like a large competitor’s top line condenser mic.
• Bass cut gives a dry but highly intelligible sound. Crisp.
dB
• Bass boost “fattens” the sound but is very listenable.
Does not get midbass boomy.
• Midrange cut sounds very smooth. Almost a “crooner”
quality. A sweet sound.
-5
-10
• Midrange boost is likely to be useful in a system that is
midrange shy.
• Treble cut has a “mellow” sound. The capsule has a solid high end so a little cut does not ruin the response.
• Treble boost might be fine on some sound systems. The sound doesn’t get harsh (showing that the response was
smooth) but sibilants are a little too much. Should be used in moderation.
T187 Bass/Midrange/Treble Boost/Cut
10Hz
100Hz
1KHz
10KHz
Rio Rancho, NM – USA
5
BASS FILTER
In addition to the tone controls, the T187 also has a built in bass filter. This filter is fixed and cannot be adjusted or
defeated. Low frequency noise is much more of a problem with wireless microphones than with conventional microphones. With a regular mic, low frequency wind noise, breath thumps or handling rumble can be filtered out at the
control board before the noise causes problems with the following electronics or speaker systems. But with a
wireless microphone, the electronics that will be overdriven are right in the wireless microphone. Filtering at the
control board is much too late. To solve this problem, the VariMic has a low frequency filter that is so sharp that it
can remove low frequency noise without affecting any wanted vocals. It consists of a 36 dB per octave filter circuit to
sharply remove low frequency noise below 75 Hz without affecting vocal fundamentals. The lowest operatic bass
voice fundamental is 82 Hz. See the curve below.
20
0dB
-3dB @ 71Hz
-20
-20dB @ 50Hz
-40
-60
10Hz
100Hz
1KHz
ATTENUATOR
T187 Bass Filter
The VariMic head includes an attenuator to provide an additional 15dB of
headroom when needed. The attenuator should only be used when the normal
Mic Level pot is already turned down as far as it will go and the signal through
the mic is still too hot. The attenuator control is a 16-position switch marked 0
through F. “F” is minimum attenuation or the highest signal level. “0” is maximum attenuation or the lowest signal level. For the maximum amount of headroom, set the switch to “0.”
Note: The attenuator should not be used as a level control. The Audio
Level control inside the battery compartment is the main level control.
Adjust the attenuator only when the Audio Level control is turned
completely down and more headroom is still needed. Be sure to set the
attenuator back to its original setting for normal operation.
10KHz
6
VHF Hand-held Transmitter
BATTERY INSTALLATION
The T187 transmitter is powered by a standard alkaline 9 Volt battery. It is important that you use ONLY an ALKALINE battery for reliable operation. Alkaline batteries will provide about 15 hours of operation and the battery status
lamp will function normally. Standard zinc-carbon batteries marked “heavy duty” or “long-lasting” are not adequate.
They will provide only about 4 hours of operation. Similarly, nicad rechargeable batteries only provide about 4 hours
of operation, and will run down quite abruptly.
The battery compartment is located in the lower section of the transmitter, between two printed circuit boards. To
install a fresh battery, follow the steps illustrated below. Look inside the battery compartment when the cover is off
and take note of the two differently sized holes in the battery contact pad. Insert the battery so that the large hole in
the battery contact pad will line up with the large contact on the battery when it is installed. The spring-loaded
plunger in the bottom of the compartment (opposite the contact pad) secures the battery in place.
The battery status is indicated by an LED on the bottom panel. The LED will glow brightly when the battery is good
and will dim as the battery condition deteriorates. The LED is at full brightness with a new battery. After 12 to 15
hours of operation using an alkaline battery, the battery voltage will be about 7 Volts and the LED will be completely
out.
DO NOT FORCE DOOR!
Remove
Cover
Step 1
Pull ring
outward
Rotate ring
1/8 turn
PA
Step 2
EXTERNAL
LED
OFF
EXTERNAL
SWITCHES
BYPASS
Step 3
EXTERNAL
LED
OFF
+
–
EXTERNAL
LED
OFF
EXTERNAL
SWITCHES
BYPASS
Step 4
+
–
EXTERNAL
SWITCHES
BYPASS
Step 6
Insert
Battery
Rotate ring to
lock closed
EXTERNAL
LED
OFF
PA
Step 5
Alternate Method:
Depress the plunger with the corner
of the battery and slide the battery
into the compartment. Note that the
locking ring is in the closed position
for this procedure.
Replace
cover
EXTERNAL
SWITCHES
BYPASS
Step 6
Ring will sit
flush in
closed position
Rio Rancho, NM – USA
7
OPERATING INSTRUCTIONS
1) Install a fresh battery according to the instructions on page 7.
2) Move the internal bypass slide switches to the left-hand position so that the battery status LED and the bottom
panel switches will operate.
3) Move the “A” (audio) switch to “OFF” and the “P” (power) switch to ON (in that order). Observe that the battery
status LED is brightly lit. If the LED is dim, replace the battery.
4) Hold the microphone in the same position that will be used in actual operation.
5) While speaking or singing at the same voice level that will be actually used, observe the MOD LEVEL LEDs on
the PC board. Adjust the AUDIO LEVEL control knob until the LEDs begin to light. The first LED lights when the
audio level is about 10 dB below full modulation and limiting. The second LED (closest to the knob) lights when
the limiter begins to operate. There is 20 dB of headroom above the limiter LED and it is normal that it lights up
5% to 10% of the time during use.
5) Once the gain has been adjusted, the transmitter audio can be turned on to make sound system level adjustments. Operate the “A” (audio) switch to ON position and adjust the receiver and/or sound system level as
required.
OPERATING NOTES
The AUDIO LEVEL control knob should not be used to control the volume of your sound system. 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 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 along with the audio.
The first LED turns on at -10dB below full deviation. The limiting LED (closest to the knob) turns on at full deviation
and indicates that the input shunt compressor is operating. The input compressor operates over a full 20dB 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 for optimum signal to noise
ratio.
Different voices will usually require different settings of the AUDIO LEVEL control, so check this adjustment frequently. If several different people will be using the T187 and there is not time to make the adjustment for each
individual, adjust it for the loudest voice.
8
VHF Hand-held Transmitter
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) External LED is turned off. Check internal slide switch.
2) Battery is inserted backwards.
3) Battery is dead.
NO TRANSMITTER MOD LEVEL LEDs 1) Gain control turned all the way down.
2) Battery is in backwards. Check power LED.
3) Mic capsule is damaged or malfunctioning.
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.
NO SOUND AND RECEIVER
MOD LEVEL LEDs ARE OFF 1) Transmitter audio muted. Make sure bottom panel “A”
switch is turned on. Push switch toward the letter “A” to
turn the audio on.
NO SOUND BUT RECEIVER
MOD LEVEL LEDs ARE ON 1) Receiver audio is muted. Refer to receiver manual.
2) Receiver audio output is disconnected or cable is defective or mis-wired.
3) Sound system or recorder input is turned down.
DISTORTED SOUND AND/OR
MOTORBOATING 1) Transmitter gain (audio level) is too high. Speak or sing
into the transmitter and check mod level lamps on transmitter and receiver.
2) Receiver output may be mis-matched with the sound
system or recorder input.
3) Excessive wind noise or breath “pops.”
4) RF feedback getting into Vari-Mic mic capsule. Ensure
that the windscreen is present and screwed down snugly.
HISS AND NOISE -- AUDIBLE DROPOUTS 1) Transmitter gain (audio level) too low.
2) Receiver antenna missing or obstructed.
3) 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) Move transmitter closer to the user’s mouth.
Rio Rancho, NM – USA
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 interconnecting cords and then go through the TROUBLE SHOOTING 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. Regular: (505) 892-4501
PO Box 15900 581 Laser Rd. Toll Free (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
VHF Hand-held Transmitter
SPECIFICATIONS AND FEATURES
Operating frequencies: 150 to 216 MHz
RF Power output: 50mW
Deviation: ± 15kHz
Spurious emissions: 55dB below carrier
Equivalent input noise: -126dBV
Input compressor: Soft compressor, 20 dB range allows 3 Volt max. input
Gain control range: 43dB; semi-log rotary control
Indicators: • Dual LEDs for modulation level and onset of limiting
Controls: • Power ON/OFF (located on external panel)
Battery: Any 9 Volt alkaline
Weight: 11 ozs. with Shure SM87 mic capsule and battery
Dimensions: 1.6 inches avg. diameter x 9.1 inches length (SM87)
• Power/battery status LED
• Audio ON/OFF (located on external panel)
• EXT SWITCHES BYPASS (located under battery door)
• EXTERNAL LED ON/OFF (located under battery door)
Emission Designator: 54KOF3E
Specifications subject to change without notice.
Rio Rancho, NM – USA
11
LIMITED ONE YEAR WARRANTY
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.
LECTROSONICS, INC.
581 LASER ROAD
RIO RANCHO, NM 87124 USA
November 1, 2001
Loading...