General Technical Description - Lectrosonics T6 Operating Instructions Manual

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.
+5V BIAS
SUPPLY LF
MIC
ROLL-OFF
JACK
1
2
3 INPUT
BUFFER
AMP
4
5
SHUNT
LIMITER
LIMIT
LED
SYNTHESIZER
FREQ
SWITCHES
uP
4

GENERAL TECHNICAL DESCRIPTION

LP
FILTER
AUDIO
LEVEL
Vref
BASS
TREBLE
SET
LED
PEAK AUDIO
INDICATOR &
LIMITER
DRIVER
COMPANDED
LOW PASS
FILTER
E PROM 2
IFB T6 Block Diagram
COMPANDOR
LP FILTER
HP FILTER
Vreg
Vreg
AUDIO
VOLTAGE
CONTROLLED
OSCILLATOR
COMPANDED AUDIO
TO XMTR
PILOT
TONE
OSC
PWR
DELAY
+5VDC
+3.6VDC
TRANSMITTER
+9VDC
PWR
LED