Lectrosonics T1 User Manual
T1
Multi-Frequency IFB Transmitter
INSTRUCTION MANUAL
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Rio Rancho, NM, USA
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T1
LECTROSONICS, INC. 2
Multi-Frequency IFB Transmitter
Table of Contents
Introduction ............................................................................................................................................................................................4
General Technical Description ..............................................................................................................................................................5
Audio Input Interface ............................................................................................................................................................................ 5
Audio Processor ...................................................................................................................................................................................5
Compandor Noise Reduction ............................................................................................................................................................... 5
T1 IFB Transmitter Block Diagram ........................................................................................................................................................5
Pilot Tone ..............................................................................................................................................................................................6
Frequency Synthesizer ......................................................................................................................................................................... 6
Power Delay .........................................................................................................................................................................................6
Microcontroller ......................................................................................................................................................................................6
Transmitter ............................................................................................................................................................................................6
Antenna System ...................................................................................................................................................................................6
Front Panel Controls and Functions ....................................................................................................................................................7
T1 Front Panel ......................................................................................................................................................................................7
OFF/TUNE/XMIT Switch ...................................................................................................................................................................... 7
Power Up Sequence .............................................................................................................................................................................7
LED Display ..........................................................................................................................................................................................7
Adjusting Display Intensity ................................................................................................................................................................... 7
Freq Buttons (Up and Down) ................................................................................................................................................................7
Audio Level Control ..............................................................................................................................................................................7
-20/0 LEDs ...........................................................................................................................................................................................7
Rear Panel Controls and Functions .....................................................................................................................................................8
T1 Rear Panel ...................................................................................................................................................................................... 8
XLR Jack ..............................................................................................................................................................................................8
Mode Switches .....................................................................................................................................................................................8
12 VDC (Power Input Connector) .........................................................................................................................................................8
Antenna ................................................................................................................................................................................................8
Installation and Operation ..................................................................................................................................................................... 9
Operating Notes ...................................................................................................................................................................................10
Accessories ..........................................................................................................................................................................................10
Troubleshooting ...................................................................................................................................................................................11
Frequency Blocks and Ranges ...........................................................................................................................................................12
Specifications .......................................................................................................................................................................................13
Service and Repair ............................................................................................................................................................................... 14
Returning Units for Repair ..................................................................................................................................................................14
Rio Rancho, NM 3
T1
Introduction
Thank you for selecting the Lectrosonics frequency
agile, narrowband, T1 IFB (Interruptible Foldback)
transmitter. The T1 is the result of over 80 years of
engineering experience with the very latest components, in a design that addresses the most demanding
professional applications.
The Lectrosonics T1 IFB Transmitter along with the
companion R1 or R1a IFB Receivers allow on-air talent
to monitor program audio and receive cues from
directors and other production personnel.
The design of the T1 IFB Transmitter was the direct
result of numerous conversations with users, production
personnel 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 T1. Two hundred fifty six frequencies are user selectable in 100 kHz steps to
alleviate interference problems in travelling venues.
The T1 IFB Transmitter is a rugged, machined aluminum package. The input section is adjustable for
virtually any microphone or line level audio source.
Level indicating LEDs are provided on the control panel
to make level settings quick and accurate, without
having to view the receiver. The antenna is a detachable, locking 1/4 wavelength flexible bronze cable that
connects to a 50 Ohm BNC connector on the transmitter.
Only the T1 IFB Transmitter is covered in this manual.
Companion receivers are covered in separate manuals.
The T1 IFB Transmitter will operate with any
Lectrosonics R1 or R1a IFB Receiver in the same
frequency group.
LECTROSONICS, INC. 4
General Technical Description
Multi-Frequency IFB Transmitter
The T1 IFB Transmitter is comprised of a number of
functional subsystems, including Audio Input Interface,
Audio Processor, Pilot Tone, Frequency Synthesizer,
Microcontroller, Transmitter, Antenna System and
Power Supply. (See block diagram.)
The T1 is designed to operate with the Lectrosonics R1
and R1A IFB receivers, and Lectrosonics R400A
receivers, and features microprocessor control of 256
operating frequencies within any one of at least nine
frequency bands.
The T1 uses 20 kHz deviation for an efficient use of
bandwidth. The transmitter circuits are all regulated for
frequency stability and high audio performance. The
input amplifier is a discreet differential circuit which can
be adjusted to allow the use of many different input
sources.
Audio Input Interface
The input sensitivity and XLR pin functions can be
customized using a DIP switch located on the back
panel. Different combinations of gain and input configurations are possible without rewiring the mic connector.
Pin 1 of the XLR input connector is normally connected
directly to ground but an internal jumper can be moved
if a floating input is desired.
The Audio (+) and (–) are “dry” inputs and can each
withstand +/- 50 VDC.
Warning: Direct connection to a phone line can
damage the transmitter’s inputs.
Audio Processor
The Audio Processor section has several functions,
including signal limiting, filtering and companding
(dynamic range compression). Audio limiting is accomplished by a Shunt Limiter placed before the filter and
compandor circuits. A Bandpass Filter limits the audio
bandwidth to 100 Hz at the low end and 10 kHz in the
upper range. The single band compandor circuit
compresses the dynamic range of the audio signal and
prepares it for transmission. It is one half of a system
that requires a matching receiver to decode the signal
and restore its original dynamic range.
Compandor Noise Reduction
The single band compandor is a high quality audio
device that processes (compresses) the input signal so
that the large dynamic ranges of the input signals can
be transmitted to the receiver without overload or noise.
A complementary system in the receiver recovers
(decompresses) 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 10 dB
signal to noise improvement. Matching de-emphasis is
provided in all receivers.
T1 IFB Transmitter Block Diagram
T1 IFB Transmitter
Block Diagram
Rio Rancho, NM 5
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