Lectrosonics UT200c User Manual
UT200C
FREQUENCY-AGILE
HAND-HELD TRANSMITTER
OPERATING INSTRUCTIONS
and trouble-shooting guide
LECTROSONICS, INC.
Rio Rancho, NM
www.lectrosonics.com
INTRODUCTION
Thank you for selecting the Lectrosonics UT200C hand-held wireless transmitter. The
UT 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 UT200C 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 UT200C. Two hundred fifty six frequencies are user
selectable in 100kHz steps to alleviate interference problems in travelling venues
The UT200C 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 UT200C transmitters are covered in this manual. Companion receivers are
covered in separate manuals. The UT200C will operate with any 200 Series Lectrosonics receiver in the same frequency group.
TABLE OF CONTENTS
INTRODUCTION .................................................................................................. 2
GENERAL TECHNICAL DESCRIPTION ............................................................ 3
CONTROLS AND FUNCTIONS .......................................................................... 5
BATTERY INSTALLATION ................................................................................... 8
OPERATING INSTRUCTIONS ............................................................................ 9
OPERATING NOTES ........................................................................................... 9
ADJUSTING THE TRANSMITTER FREQUENCY ............................................ 10
TROUBLESHOOTING ....................................................................................... 11
SPECIFICATIONS .............................................................................................. 12
SERVICE AND REPAIR ..................................................................................... 13
RETURNING UNITS FOR REPAIR ................................................................... 13
WARRANTY ......................................................................................... Back cover
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Frequency Agile Handheld Transmitter
GENERAL TECHNICAL DESCRIPTION
The UT200C transmitters are comprised of a number of functional sub-systems as shown in the block diagram below.
GENERAL
The 200 system uses 75kHz wide deviation for an extremely high signal to noise ratio. 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 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.
DUAL BAND COMPANDOR
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 200 system
introduces an entirely new approach to solving this basic problem, called “dual-band companding.”
There are actually two separate compandors in the 200 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.
NO PRE-EMPHASIS/DE-EMPHASIS
The signal to noise ratio of the 200 system is high enough to preclude the need for conventional pre-emphasis (HF
boost) in the transmitter and de-emphasis (HF roll off) in the receiver. Pre-emphasis and de-emphasis in an FM radio
system usually provides about a 10dB improvement in the signal to noise ratio of the system, but the high frequency
boost in the transmitter must be removed in a purely complementary manner or else the frequency response of the
original audio signal will be altered.
Pre-emphasis can also cause distortion in the receiver. As this signal is passed through the IF filters in the receiver,
distortion can be produced, most noticeably at full modulation. De-emphasis cannot be applied until the signal is
converted into audio, so there is no way around this problem short of eliminating pre-emphasis altogether. Neither of
these problems occur in the 200 system. The dual-band compandor in the 200 Series system essentially provides a
dynamic pre-emphasis/de-emphasis function with extremely low distortion.
MIC
ELEMENT
SHUNT
LIMITER
PREAMP
LIMIT
LED
SET
LED
INPUT
AMP
AUDIO
LEVEL
PEAK AUDIO
INDICATOR &
LIMITER
DRIVER
LP
FILTER
Vref
TREBLE
COMPANDOR
BASS
LP FILTER
HP FILTER
Vreg
Vreg
PILOT
TONE
OSC
+5VDC
+3.6VDC
COMPANDED AUDIO
TO XMTR
MUTE
PWR
+9VDC
PWR
LED
PHASE LOCKED LOOP
DIVIDER
FREQ
SWITCHES
PRESCALER
LOW PASS
FILTER
COMPANDED
AUDIO
Rio Rancho, NM - USA
VOLTAGE
CONTROLLED
OSCILLATOR
TRANSMITTER
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PILOT TONE SQUELCH
The 200 system utilizes an ultrasonic tone modulation of the carrier to operate the receiver squelch. This “pilot tone”
consists of a 32kHz signal mixed with the audio signal following the microphone preamp, just after the compandor, to
control the audio output muting of the receiver. The pilot tone is filtered out of the audio signal immediately after the
detector in the receiver so that it does not influence the compandor or various gain stages. The basic benefit of the
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. This is extremely important
in applications such as with an automatic microphone mixer.
WIDE-BAND DEVIATION
75kHz deviation improves the capture ratio, signal to noise ratio and AM rejection of a wireless system dramatically.
Almost all other wireless systems use less than 75kHz deviation.
LONG BATTERY LIFE
High efficiency circuits throughout the design allow over 4 hours of operation using a single 9 Volt alkaline battery
(over 12 hours with a new lithium battery.) The battery compartment is a unique mechanical design which automatically adjusts to fit any brand of alkaline or lithium battery. Battery replacement is easily accomplished by releasing
the bottom and removing the battery cover. The battery contacts are spring loaded to prevent “rattle” as the unit is
handled. The UT200C contains a battery status monitoring circuit which monitors and sends the battery status to the
UDR200B receiver. The battery status is displayed on the front of the receiver.
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 of the unit, provide 256 frequencies in 100kHz steps over a 25.5MHz range.
This alleviates carrier interference problems in mobile or travelling applications.
ANTENNA
The high output antenna utilizes the lower half of the printed circuit boards as one radiating element, with the upper
half of the PC boards and mic capsule as the other half of the dipole configuration. This allows the mic to be held in
any position, since the user’s hands have little or no effect on the radiated power.
MICROPHONE ELEMENT
The UT200C includes the Lectrosonics VariMic mic element. The VariMic is an cardioid condenser back electret
microphone that is adapted for the unique circumstances of wireless microphones. The problems it solves are
dynamic range, handling noise and low frequency noise (rumble or wind).
In the VariMic, an unusual pumped source FET circuit increases the usable dynamic range 12dB and greatly reduces
distortion, just as if the FET were being supplied with 48 Volts. In addition, a unique 16 position sensitivity control at
the element itself can adjust the sensitivity in 15 steps over a 15 dB range. This is in addition to the normal gain
control in the wireless microphone. The result is the widest dynamic range of any condenser mic in a wireless
microphone.
The VariMic has a three point damped rubber suspension to reduce high frequency handling noise and a generous
sized windscreen to keep wind noise and breath pops away from the microphone.
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. Isn’t it nice to know that it will come ripping right through.
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Frequency Agile Handheld Transmitter
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. When the battery voltage reaches 7 Volts, the LED will be completely dark. Note: this
LED will not light if the EXT LED switch is in the OFF position.
“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 trans-
mitter to be adjusted without feedback from the sound system. This switch will do nothing if the EXTERNAL
SWITCHES switch is in the BYPASS position.
INTERNAL
FREQUENCY ADJUST
Two rotary switches adjust the center frequency of the carrier. The
1.6M is a coarse adjustment and the 100K is the fine adjustment.
Each transmitter is factory aligned at the center of its operating
range. The default position of the frequency select switches is in
the center of the transmitter’s range. See page 10 for details on
adjusting the transmitter frequency.
Audio Power
On/Off On/Off
PA
Frequency switches
located behind door.
MOD LEVEL LEDs
These LEDs (located under the battery door) 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 and
are easily viewed when holding the transmitter in a normally used position.
Mod Level
LEDs
Gain Control
AUDIO
LEVEL
AUDIO LEVEL
This knob (also located underneath the battery door) is operated while speaking or singing into the transmitter to
adjust the audio gain of the transmitter for the correct amount of modulation. The LEDs located next to it indicate the
modulation level as the gain is adjusted. See page 6 for details on this very important adjustment.
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. The
external switches are bypassed when this switch handle is moved toward the bottom of the
unit.
Bypass Switches
EXTERNAL
EXTERNAL
SWITCHES
BYPASS
LED
OFF
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. The external
LED is disabled when this switch handle is moved toward the bottom of the unit.
Rio Rancho, NM - USA
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