Lectrosonics UH195 User Manual

UH195

Plug-on Transmitter

OPERATING INSTRUCTIONS

and trouble-shooting guide

LECTROSONICS, INC.

Rio Rancho, NM

INTRODUCTION

Thank you for selecting the Lectrosonics UH195 plug-on transmitter. The UH195
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 UH195 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 UH195.

The UH195 is a rugged, machined aluminum package. Phantom power is provided
on pins 2 and 3. Level indicating LEDs are provided 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.

Only the UH195 transmitter is covered in this manual. Companion receivers are
covered in separate manuals. The UH195 will operate with any 195 Series
Lectrosonics receiver on the same frequency.

TABLE OF CONTENTS

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

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

INSTALLATION ..................................................................................................... 4

FRONT PANEL DESCRIPTION........................................................................... 5

REAR PANEL DESCRIPTION ............................................................................. 6

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

REMOTE LEVEL CONNECTIONS ...................................................................... 9

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

SERVICE AND REPAIR ..................................................................................... 10

RETURNING UNITS FOR REPAIR ................................................................... 10

SPECIFICATIONS .............................................................................................. 11

APPENDIX 1: SERIAL PORT HARDWARE AND SOFTWARE ....................... 12

SERIAL PORT COMMANDS AVAILABLE ........................................................ 13

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

The UH195 transmitter is FCC type accepted under Part 74: 470-608 MHz

2

Portable Wireless Sound System

GENERAL TECHNICAL DESCRIPTION

The UH195 transmitter is comprised of a number of functional sub-systems as shown in the block diagram below.

The 195 system uses 75kHz wide deviation. 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 oscillator crystal is shock mounted to provide rugged­ness. 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 40dB above full modulation.

The 195 system utilizes an ultrasonic tone modulation of the carrier to operate the receiver squelch. This “pilot tone”
consists of a 33kHz 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 sound system.

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 195
system introduces an entirely new approach to solving this basic problem, called “dual-band companding.”

There are actually two separate compandors in the 195 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.

MIC

JACK

SHUNT

LIMITER

+5V BIAS
SUPPLY

INPUT
AMP

LIMIT

LED

SET
LED

AUDIO
LEVEL

FILTER

Peak Audio

Indicator &

Limiter Driver

LP

Vref

COMPANDOR

BASS

TREBLE

COMPANDED

LP FILTER

HP FILTER

AUDIO

Vreg

Vreg

PILOT
TONE

OSC

+5VDC

+3.6VDC

X4

+5V

DELAYED

OFF

X2 X2 X2

ONMUTE

-9V

+9VDC

PWR
LED

Rio Rancho, NM – USA

XTAL OSC

UHF TRANSMITTER

3