Lectrosonics IFBT5 User Manual

T5

MULTI-FREQUENCY IFB TRANSMITTER

EURO MODEL

OPERATING INSTRUCTIONS

and trouble-shooting guide

LECTROSONICS, INC.

www.lectrosonics.com

0885

INTRODUCTION

Thank you for selecting the Lectrosonics frequency agile, narrowband, T5 IFB
transmitter. The T5 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 T5 IFB Transmitter along with the companion R5 IFB Receiver
allow on-air talent to monitor program audio and receive cues from video directors
and other production personnel.

The design of the T5 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 T5. Two hundred fifty six frequencies
are user selectable in 100 kHz or 25 kHz steps to alleviate interference problems in
travelling venues. 100 kHz channel spacing is standard. 25 kHz channel spacing
can be programmed into a unit by the factory or by authorized service centers.

The T5 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 mini-jack on the transmitter.

Only the T5 IFB Transmitter is covered in this manual. Companion receivers are
covered in separate manuals. The T5 IFB Transmitter will operate with any Lec­trosonics R5 IFB Receiver in the same frequency group.

TABLE OF CONTENTS

INTRODUCTION ...................................................................................................... 2

GENERAL TECHNICAL DESCRIPTION ................................................................ 3

FRONT PANEL CONTROLS AND FUNCTIONS ................................................... 5

REAR PANEL CONTROLS AND FUNCTIONS ...................................................... 6

INSTALLATION AND OPERATION ......................................................................... 7

OPERATING NOTES ............................................................................................... 7

MODE SWITCHES AND GROUND LIFT JUMPER ............................................... 8

TROUBLESHOOTING.............................................................................................. 9

FREQUENCY BLOCKS AND RANGES ............................................................... 10

REPLACEMENT PARTS and ACCESSORIES .................................................... 10

SPECIFICATIONS AND FEATURES .................................................................... 11

WARRANTY .............................................................................................. Back cover

The T5 IFB transmitter is FCC type accepted under Part 74: 470 - 608MHz and 614 - 806MHz

2

GENERAL TECHNICAL DESCRIPTION

C

IFB Transmitter

The T5 IFB Transmitter is comprised of a number of functional sub-systems as shown in the block diagram below.

GENERAL

The T5 is designed to operate with the Lectrosonics R5 IFB Receiver and features microprocessor control of 256
frequencies of operation within any one of at least thirteen frequency bands. (See page 10.)

The T5 uses 20kHz 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

The input sensitivity and XLR pin functions can be customized using a clever dip switch circuit. Several different
combinations of gain and input hookup 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 +/- 50Vdc. Direct connection to a phone line can
damage the inputs.

AUDIO PROCESSOR

The Audio Processor section has several functions. Audio limiting is accomplished in the Shunt Limiter while the
Bandpass filter limits the audio bandwidth to 100Hz at the low end and 10kHz in the upper range. The single band
compandor circuit is one half of a system that requires a matching receiver to decode the signal and restore it to its
original dynamic range.

Frequency Synthesizer

Serial

Control

Input

Amplifier

Circuit

Power
On/Off

LP

Filter

VCO

Display

Driver

Audio Processor

Shunt

Limiter

PLL &

Prescaler

Memory

Down

XLR

Input

onnector

2

3

1

Input

Power

11-18 VDC

Polyfuse

Up

Audio Input Interface

FREQ

Controller

Mode

Set

Switches

Power Delay

Transmitter

Buffer

100Hz-10kHz

+10V

+5V

+5.5V

+6V

BP

Filter

Pre­Amp

Pilot Tone

Oscillator

Power

Control

Compandor

Amp

Filter

Output

Amp

T5 IFB Transmitter Block Diagram

Rio Rancho, NM – USA

3

GENERAL TECHNICAL DESCRIPTION

COMPANDOR NOISE REDUCTION

The single band compandor is a high quality audio device that processes the input signal such that the 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 improvement. Matching de-emphasis is provided in all receivers.

PILOT TONE

The T5/R5 system utilizes an ultrasonic tone modulation of the carrier to operate the receiver squelch. This “pilot
tone” consists of a 29.997kHz signal mixed with the audio signal, 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 that include an automatic microphone mixer.

FREQUENCY AGILITY

The transmitter uses a synthesized, frequency selectable main oscillator. The frequency is extremely stable over a
wide temperature range and over time. Two push-button switches, located on the front panel of the unit, provide 256
frequencies in 100 kHz or 25 kHz steps over a 25.5 MHz range. This alleviates carrier interference problems in
mobile or travelling applications.

MICROCONTROLLER

Frequency adjustment and display are handled by the microprocessor. Nonvolatile memory is provided for holding
the last frequency used even if power is removed from the unit for any length of time. Each time the transmitter is
powered up it will display the last frequency used.

TRANSMITTER

The T5 transmitter operates at 50mW*. The transmitter circuits are buffered and filtered for exceptional spectral
purity. The extra clean signal that results reduces the chances for interference between multiple transmitter installa­tions.

ANTENNA

At UHF frequencies, where wavelengths and antennas are shorter than at VHF frequencies, a resonant length
antenna is preferred. The antenna on the T5 consists of a flexible 1/4 wavelength bronze cable, detachable via a
BNC
connector.

POWER DELAY

There is a 5 second power on delay to prevent audio thumps when switching from XMIT to TUNE or from TUNE to
OFF. This delay also gives the PLL synthesizer time to fully stabilize. When the transmitter is powered OFF the Pilot
Tone is first turned off muting the audio at the receiver before the rest of the transmitter is powered down preventing
clicks, thumps or feedback from entering the sound system. When switching the power off then back on, always
allow the display to extinguish before switching the power back on.

* May be 10mW depending on destination country.

4