Lectrosonics T6 User Manual

T6

MULTI-FREQUENCY IFB

BELT-PACK TRANSMITTER

EURO MODEL

OPERATING INSTRUCTIONS

and trouble-shooting guide

LECTROSONICS, INC.

www.lectrosonics.com

0885

TABLE OF CONTENTS

INTRODUCTION ..................................................................................................... 3

GENERAL TECHNICAL DESCRIPTION ............................................................... 4

CONTROLS AND FUNCTIONS ............................................................................. 6

BATTERY INSTALLATION ..................................................................................... 8

OPERATING INSTRUCTIONS ............................................................................... 8

OPERATING NOTES ............................................................................................. 9

ADJUSTING THE TRANSMITTER FREQUENCY ................................................ 9

MICROPHONE CORD TERMINATION ................................................................ 10

5-PIN INPUT JACK WIRING ............................................................................... 11

A6U UHF ANTENNA ............................................................................................ 13

TROUBLESHOOTING .......................................................................................... 14

SPECIFICATIONS AND FEATURES .................................................................. 15

SERVICE AND REPAIR .........................................................................Back cover

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

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Multi-Frequency IFB Belt-Pack Transmitter, Euro Model

INTRODUCTION

Thank you for selecting the Lectrosonics IFB T6 multi-frequency, IFB transmitter. The
IFB T6 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 IFB T6 transmitter 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 IFB T6. There are 256 user selectable
frequencies in 25kHz steps to alleviate interference problems in travelling venues.
Also, the low frequency roll-off is user adjustable to adapt to varying acoustic envi­ronments and preferences.

The IFB T6 is a rugged, machined aluminum package with a removable, spring
loaded belt clip. The input section provides a correct input tap for virtually any
microphone or line level audio source. 5 Volts of bias voltage is available to power
electret mics with either positive or negative bias. Level indicating LEDs are provided
on the control panel to make level settings quick and accurate, without having to
view the receiver. The battery compartment accepts any 9 Volt alkaline battery and
makes a positive connection via self-adjusting contacts. The antenna is a detach­able, locking 1/4 wavelength flexible bronze cable that connects to a 50 Ohm SMA
port on the transmitter.

Only the IFB T6 transmitter is covered in this manual. Companion IFB receivers are
covered in separate manuals.

Rio Rancho, NM – USA

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GENERAL TECHNICAL DESCRIPTION

The IFB T6 transmitters are comprised of a number of functional sub-systems as shown in the block diagram below.

GENERAL

The system uses 20kHz wide deviation for high signal to noise ratio. The transmitter circuits are all regulated to allow
full output power from the beginning (9 Volts) to the end (6.5 Volts) of battery life. The input amplifier uses a Motorola
33178 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.

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.

MIC

JACK

1
2
3
4
5

FREQ

SWITCHES

LIMIT

LED

+5V BIAS

SUPPLY

BUFFER

SHUNT

LIMITER

SYNTHESIZER

uP

LF
ROLL-OFF

INPUT
AMP

AUDIO
LEVEL

SET
LED

LOW PASS

FILTER

2

E PROM

LP

FILTER

PEAK AUDIO

INDICATOR &

LIMITER
DRIVER

COMPANDOR

Vref

BASS

TREBLE

COMPANDED

LP FILTER

HP FILTER

AUDIO

IFB T6 Block Diagram

PILOT
TONE

OSC

Vreg

+5VDC

Vreg

+3.6VDC

VOLTAGE

CONTROLLED

OSCILLATOR

COMPANDED AUDIO

PWR

TRANSMITTER

TO XMTR

DELAY

+9VDC

PWR

LED

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Multi-Frequency IFB Belt-Pack Transmitter, Euro Model

PILOT TONE SQUELCH

The IFB system utilizes an ultrasonic tone modulation of the carrier to operate the receiver squelch. This “pilot tone”
consists of a 30kHz 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.

LONG BATTERY LIFE

High efficiency circuits throughout the design allow over 7 hours of operation using a single 9 Volt alkaline battery. (A
9V lithium battery will provide over 17 hours of operation.) The battery compartment is a unique mechanical design
which automatically adjusts to fit any brand of battery. The battery contacts are spring loaded to prevent “rattle” as the
unit is handled.

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 panel of the unit, provide a maximum of 256 frequencies in 25kHz steps
minimum over a maximum range of 25.5MHz. This alleviates carrier interference problems in mobile or travelling
applications.

ANTENNA

At UHF frequencies, where wavelengths and antennas are shorter than at VHF frequencies, a resonant length wire is
preferred over using the microphone cable as the antenna. The antenna on the IFB T6 consists of a flexible 1/4
wavelength bronze cable, detachable via an SMA connector. The impedance of this connector is 50 Ohms.

Rio Rancho, NM – USA

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