RTS TWI222, TWI224, TW1222-T, TW1222-CM, TWI-SK7O-DCU Technical Manual

TECHNICAL MANUAL

I

MODEL

TW

Interface Units

TM3600

TW1222

1

OIN

9300-360040

Including

TW1222-T

TW1222-CM

TWI-SK7O-DCU

1

~~12241

Intercom System

A

Telex

RTS SYSTEMS

Communications Product

TECHNICAL

MANUAL

Model TWI224

PROPRIETARY NOTICE

The information and design disclosed herein were
originated by and are the property of RTS Systems.
RTS Systems reserves
manufacturing, reproduction, use an sales rights
thereto, and to any article disclosed therein, except to
the extent rights are expressly granted to others.

COPYRIGHT NOTICE

Copyright
USA.
in part without written permission from RTS Systems

is

prohibted.

1988

by

ALI

rights reserved. Reproduction in whole or

all

patent, proprietary design,

RTS Systems, Burbank, California,

/TWI222

Interface Units

AND

UNPACKING INFORMATION

Immediately upon receipt of the equipment, inspect

the shipping container and the contents carefully for
any discrepancies or damage. Should there be any,
notify the freight company and the dealer at once.

The shipping Model

should
Ordering Number 9000-2195-00

Ordering Number 9000-2184-00

a

contain

RTS Systems
Part Number Descriotion

9010-2195-00 Model TWI224
9010-2184-00 Model TWI222
9300-3600-00 Technical Manual

TWI224

the following components:

/

TWI222 container

INSPECTION

--

TWI224

--

TWI222

Printing History:
First Edition: July 1980

6

Second Edition: July 1989

This manual
Department of RTS Systems, whieh is responsible for
its contents.

Written by: Daniel
Edited by:

Address

to:
Director of Engineering

RTS Systems
1100 West Chestnut Street
Burbank,

is

published by the Engineering

F.

Register

Sheryl D. Thompson

all

communication regarding

CA

91506 USA

this

publication

RTS Systems

Burbank,

CA

91506 / FSCM: 60572

Page

ii

TM3600

/

Second Edition, July 1989

TECHNICAL

Model

TWI224 / TWI222

TABLE OF CONTENTS

MANUAL

Interface

Units

Unpacking Information
Table

Of

Contents

warranty

Shipping Information
SECTION

1.1

U

13
SECTION
Ref. No Ti&

21

22

23

2.4
sEClTON3: OPERATING INSTRUCTIONS

.......................

1:

INTRODUCTION

Introduction
Application
Spedbtiions

2:

INSTALLATION

RTS TO 4-Wue
RTS To 2-Wue Systems
RTS To
RTS To

.............................................................................................................................................

.......-

.........................................................................................................................................

"...,.,

...........

-......---.-

.........

...........................................................................................................................................

AND

SPECIFICATlONS

...........................................................................

Guide

..............................................................................................................................

........................................................................................................................................

Cameras

2-Wm

RCAPaven

Telephone

and

Intercoms

...................................................................................................................

Wetpry

Systems

...........................................................................................................

"."--"-.."."

.-..................

"

....................................................

................................................................

...............................................................................................

............................... I ....................................................................

'

1

"

.....

"

....

..

n

...

m

v

v

1-1
1-1

1-1

2-1
22
2-3
2-5

3.1

3.2

3.3

3.4
SECI'ION

Ref.

4.1 Introduction

4.2 Fuuctid Dwcription

4.3

4.4

Introduction
RTS To 4-Wue Systems Operation
RTS To 2-Wire System Operation
RTS To 2-Wire Telephone Operation..

4:

TBEORY

No Title

TWI-222

Circuit

RTS Systems Burbank,

.....................................................

OF OPERATION

...................................................................................

Block

Description

Description

....................................................................................................................................

"

...........................................................................................

........................................................................................................

....................................................................

.

.................................

..................................................................................................

.........................................

..............................

..............................................................................................

...................................................................................................................

CA

91M6

/

FSCM:

Page

6057%

iii

TM36GU

/

Second Edition,

July

3-1

3-1

3-1

3-1

4-1
4-1

4-2
4-2

1989

Model

TECHNICAL

TwI22a

/

Twrm

MANUAL

Interface

Units

SECTION
Ref. No Title

5.1
SECTION
Ref. No Title

5:

Chaghg

6.

Introduction

How To Obtain Parts
Shipping

Fi

Back Panel mbly
Front Panel Assembly
Printed Cuaut Assembly

Fd

S-ON

7:

Document

Number

MAINTENANCE

Impedance

LISTS OF

.........................................

REPLACEABLE

..................................

PARTS

........................................................................................................ 6-1

......................................................................................................................

Lists

Assembly

...........................................

........................................................................................................................................

...............................

. .

Assembly, Model

DIAGRAMS

Schematic Diagram,
Assembly
Assembly
Engiaeering Note,
wkhg

TWI-SK70-DCU,

sheet

2

Schematic Diagram, TWISK70-DCU
Assembly
TWI-SKnrDCU, Squelch
sheet 2 of
TWISKMDCU

sheet 2 of

Schematic
Assembly

Schematic Diam,

...............................................................................................................................

..............................................................................................................................

TWUZZ

Diagram,
Diam,

Diagram, TWISK70-DCU

of

2

.....

"

......

Diagram, TWI-SK7DDCU

2

......

"

..............................................................................................................................

2

........................................

Diagram,

Dim,

......................... " ...................................................................................

Interuun Interface

P.C.B.

TWU24

P.C.B.

TWI224

TWISK70DCU

4-Wue Interface W/SAP

"

."

............................

Circuit Piggyback

Squelch

Card,

Squelch Mod For

P.C.B. Squelch M&cation

Intercom Interface

........................................................................................

"

..............................

"

.............................................................................

TWI220

Interface Layout
Hold Circuit Layout

Interface Card

Interface

,,

1024,

"

......

.................................................................................

............................................

Layout

Board

Circuit Description sheet 1 of

.."

....

"....

..

..............................................................................

TWI-SK70-DCU

TwI22a

...............................................................

................. - ..............................

..................................................................

...........................................................

...................................................................

......................................................

sheet 1 of

Chart

........................

Installation

2

...................................................

"

...........................................

"

........................................

to

Interface

2

.............................................

..........................................................

For

TWISK70-DCU

.......................................................................

.......................

Card

Layout

.....................

"

...................

..............

...................

5-1

6-1

61

6-1
6-2
6-2

6-2

6-4

7-2

7-3
74

7-5

7-6
7-7

7-8
7-9

7-10

7-11

7-l2
7-I3

7-14

7-l5

7-16
7-17

RTS

Systems

Burbank,

CA

91M6

/

FSCM:

Page

60572

iv

TM3600

/

Second

Edition,

July

1989

TECHNICAL MANUAL

TWU24

Model

SYSTEMS'

RTS

The

produds of RTS Systems, , a California ProcedureForRehuns:
corporation, are warranted to be
materials and workmanship for a
from

the

date

of

RTS Systems'

period

neees~ary to remedy mvered defects appearing in
produds returned prepaid to RTS Systems,

a

Chestnut

This

warranty doas not mver any defect, malfunction
or failure
including umeasonab1e or negligent operation, abuse,
accident, failure to follow
defective

at

moditidon and repair not authorized
Systems, and shipping
serial

numbers removed or effaced are not awered

this

warranty.

To obtain warrauty
entitled "PROCEDURE FOR

THIPPING

OR

ADJUSTMENT listed below.

This

warranty
warranty given
It

is

the

responsibility of
purchase
intended

sole

to provide, without

Street, Burbank, CaliFomb,

cad

or

improper associated equipment, attempts

TO

with

that

this

purpose.

LIMITED

WARRANTY

Free

from defects in

period

sale.

obligation during the warranty

beyond

service,

charge,

the

control of RTS Systems,

instructions

damage.

follow

parts and labor

91U)6,

in

this

Products with their

the

RETURNS"

MAN~A~FOR~REP~~-

is

the

sole and

respect to RTS

the

user to determine before

product

is

exclusive

Systems'

suitable for

/

TWI222

of one year

1100

W.

USA.

Manual,

by

RTS

by

pdures

and

pr

3'-

ucts.

the

user's

Interface Units

RETURN

If

repair

is

unit

was

purchased

IF

repair

through

RTS Systems Customer Service Department, located
at the factory,

Return Authorization Number

DO NOT
FACIY)RY

RElURN

Be prepared to provide your wmpany's name,

address,

the repair, the
description of

oUwtio11~ regarding returns for repair should be
directed to:

SHIPPING TO MANUFACIVRER FOR REPAIR

phone number, a person to contact regarding

SHIPPING INSTRUCTIONS

neeeasary, contact the dealer where

the dealer

as

directed below. They

RETURN

WITHOUT

AUTHORIZATION

type

the

defect, and

Customer Service Department
RTS Systems,

1100

W.

Burbank,
Telephone:
Telex:
TeletaX

OR ADJUSTMENT

is

not possible, phone the

will

ANY

EOWIPMENT TO

FIRST

OBTAINING

NUMBER,

and quantity of equipment, a

the

serial

number(s).

Chestnut

CA

194855

(818)

St.

91506,

USA

(818) 8407311

843-7953

this

issue

THE

a

A

ANY

INCLUDING

MERClUNTABlLlTY

DURATION

AND

ALL

THE

OF

IMPLID

IMPLIED

ARE

THIS

WARRANTY

LIMITED TO THE

EXPRESS

WARRANTY.

NEITHER
WHO SELIS

LIABLE

CONSEQUENTIAL DAMAGES OF

RTS

SYSTEMS

RTS

SYSTEMS'

FOR INCIDENTAL OR

RTS Systems Burbank

NOR

CA

WARRANTIES,

LI~~ED

TEE

DEALER

PRODUCTS

ANY

IUND.

91506

/

FSCM:

All

OF

IS

page

shipments of RTS Systems, equipment should

p&

shpper. The equipment should be shipped
original pacldng cartoa;

suitable
a substitute

be

four inches of excelsior or
material.

attention of the Customer Service Department and
must include the Return Authorization Number.

Upon com letion of repairs equipment
returned

shipper.

60572

v

via

container

wrapped

Th9600

United Parcel Service or the best available

if

that

is

not available,

that

is

rigid and of adequate

container

in

All

shipments should

S

/Second Edition, July

is

used,

the equipment should

paper

and

surrounded

similar

via

United Parcel Service or specified

shock-absorbing

be

directed to the

1989

with

be

in

the

use

any

size.

at least

will

be

If

Model

TECHNICAL MANUAL

TWI224

/

TWI222 Interface

Units

SECTION
SPECIFICATIONS

The
designed to interface RTS Systems'

other interwms. These interfaces derive operating
power from the RTS line, and are transformer
isolated to prevent ground loop interference.
package styles

style

a wnsole mount package. The rack mount version
may be ordered
panel

13

This

interface for your application.

The

system to a four wire intuwm system.

include some teldon broadcast cameras, the

MeCurdy interwm systems, radiotelephones, and

cameras

(except for

camera

or two wire mode,

TWI222 interface.

better performance..

interface

RING-SLEEVE jack on

however better performance

TWI222-CM connected directly to the Carbon Mic

system's line.

2RTSTW"systemsover2telwdrypairs.

prefered to

1:

INTRODUCTION

TWU22

similar

APPLICATION GUIDE

section is intended to help you

TWU22

and

TWIZL4

are

available - a wmpact portable

to our belt

with

interface is for interfacing an RTS

which

have waxial or

the

Hitachi

has

the option of operating in either four wire Biiteral Current Sources

use

This

The

to

a Carbon Mic system

Two

TWI222's

using

2

TWI222-Ts

series of interfaces are

packs,

a rack-mount style, and

up to

three

trkial

SK-70

the

will

with

four

result in easier

TWU22

the

Carbon

will

can

over

AND

"TW"

system to

Three

interfaces in one

select

the wneet

This

would

cable adapters

DCU).

wire

mode and our Peak Current

may

also

through

be

achieved

be

used

telephone

If

your

set

up and

be

used

a

TIP-

Mic

system,

using

to interface

Thisis

lines.

to

used

TWI222 to be

from

25

ohms to

The TWI222-CM is designed to interface an RTS

"TW"

system directly to an RCA/DAVEN type
ca~bon mimophone intercom system, with an
impedance of
determine the ad impedance of your system,
divide

120

by

the number of stations on the line. For

example,

impedance of
The TWI222-T is

system to a 2-wire wet telephone line. It includes an

electronic hold circuit.

13

Typ'ncal

Balance
Input/Output Voltages:

120

10.9

SPECIFICATIONS

Gain:

Null

Capabiity

with a

1600

ohms.

4-16

ohms (30 to 7 stations). To

divided

ohms.

designed

Drive.

a

line

by

11

14

20

-30 dBm to

10

impedance ranging

stations yields a line

to interface an RTS

to

20

dB each direction

dB

+10

dBm

mA

(200

ohms)

The

TWI222 interfaces are for interfacing an RTS

two

system to other

TWU22

the

The

systems to interwm systems

200

The

is supplied in

TWI222,

TWU22

ohms nominal, with a range of

impedance may be user selected, allowing the

the TWI222-CM, and the TWI222-T.

is designed to interface RTS

RTS Systems Burbank,

wire intercom systems. The

three

different wnIigurations,

with

a line impedance of

100

to

CA

91506

400

/

7%'"

ohms.

ESCM.

Page

60572

1-1

Th9600

/

Sewnd Edition, July

1989

Model

TECHNICALMANUAL

TWI22A

/

TWI222

Interface

Units

SECI'ION

2.1

Turn

TWI-224.

224.

2-1.

terminate the

2:

RTS

TO

d

gain

Conneb

Coaned the talk

This

talk

INSTALLATION

&WIRE

and balance cont~oIs to

bus must present

TWI-224

WLMERAS

the Listen bus of the 4-wire system to pins

bus

of

4-wire output with

AND

INTERCOMS

minimum.

the

4-wire system to pins 3 and 4 of the 4-pin front-panel

a

100

ohm to

a

400

200

Connect

ohm

ohm

114

the

RTS

1

impedance

watt

resistor.

line to the

and

2

to the output of

RTS

of the +pin frontpanel

LINE

XLR

the

TWI-224.

jack

on the rear of the

XLR

on the

as

shown in figure

If

it does not,

TWI-

TO TALK BUS

4

WIRE IN

-

FOR W1224-RM(E) UNITS USE A4F (FEMALE) CONNECTOR

RTS

Systems Burbank,

Fire

Connector And Cable

CA

915061

FSCM

Wiring

Page

2.1

60572

2-1

For The

TWWO/

LO

FROM LISTEN BUS

TWI-224

Second Editioq

July

1989

22

RTS

TO

2-WIRE

SYSTEMS

Model

TECHNICAL MANUAL

lWE24

/

TWI222

Interface

Units

First cob that the

does

not,

see

section

Turn

all

gain

and balanffi controls to minimum.

TWI-222.

2.

This

Conned

input

is

the

capacitor coupled and

external

55

intercom system

on

how to change the impedance of the

external

intercom line to pins 3 and 4 of the front-panel

can

has

Connect

withstand

4

<

3

a nominal impedance of

TWI-222.

the RTS line to the RTS

dc

line

voltage-s

2

WIRE IN/OUT LO

as

high

2QO

as

ohms

LINE

XLR-4

25

volts

HI

(100

to

400

jack

on the rear of the

wnnector.

actual).

See

figure

If

it

2-

2

:

1

-

FOR TW1222-RM(E) USE

RTS Systems

Connector

Burbank,

CA

And

915061

Cable

Figure

FSCM:

Page

A4F

23

Wiring

60572

2-2

N/C

For The

TM3600/

(FEMALE) CONNECTOR

TWI-222

Second

Edition,

July

1989

23

RTS

TO

2-WIRE

Turn

all

gain

and balance controls to

LJNE

jack on the rear of the

~~nnedor.

as

high

Polarity

as M volts.

Model

TWI224 / TWI222

TELEPHONE

TWI-222T.

is

not important. See figure

WET/DRY

minimum,

Connect the telephone line to pins 3 and 4 of the front-panel

TECHNICAL

switch

tebhold switch oE Conned the

2-3.

This

MANUAL

Interface

input

is

capacitor coupled and

Units

RTS

line to the

can

withstand voltages

RTS

XLR-4

On rack mount interfaces
front-pel

See

figure

XLR-4.

2-4.

Do

Thus

not

use

(lWI-222T-RM),

the

tip and

both

jacks

ring

of the rear phone jack may

at

the

-

4

<

3

2

<

2

<

1

the rear panel stereophone jack

be

used

same

time.

WIRE IN/OUT

N/C

is

connected in parallel

instead of the front

TIP

TO TELEPHONE

RING

XLR-4

LINE

with

the

jack.

FOR TW1222-T-RM(E) USE A4F (FEMALE) CONNECTOR

RTS

Systems Burbank,

Fire

Connector And Cable

CA

915061

FSCM:

Wiriag

Page

23

60572

2-3

For The

TMbCQ/

TWI-222-T

Second

Edition,

July 1989

Model

TECHNICAL

lWI224

/

TWI222

MANUAL

Interface

Units

TO

TWI-222-

T-RM

REAR

PANZL

-

RI

TO

TELEPKNJE

RTS

Systems Burbank,

Connector

CA

And

Cable

91506/

Figure

Wi

FSCM:

60572

Page

2-4

For

2-4

The

TWI-m-T-RM

Th9600/

Second

Edition,

July

1989

2A

RTS

TO

RCA/DAVEN

Model

SYSTEMS

TECHNICAL

TWI224

/

TWI222

MANUAL

Interface Units

TWI-224

The
jacks. Use the cable shown

are

There

resulting

7).

than

TO

XLR-4

ON

TWI-224

may

be

disadvantages to

in

excesiw

sidetone on both

wnnected to a Carbon

in

figure

25.

Turn

this

method. The return

systems.

Mic

system through one of

gain

and balance controls to minimum.

signal

from

the

carbon

This

is

usually

suitable for a

TO

its

user station's

mic system

small

TIP

JACK

MIC

TIP-RING-SLEEVE

can

not be nulled out

number of stations (less

-

RING

-SLEEVE

ON

CARBON

SYSTEM

To WMed a
rear

panel of

XLR-4

conneetor. See figure

SWITCHCRAFT SWITCHCRAFT

A4-M

TWI-22Z-CM

the

TWI-222-CM.

RTS Systems Burbank,

to a Carbon

Connect the

2-2

Adapter Cable XAC

Mk

Sysrem, connect the RTS line to the RTS

line

of the

CA

9W/

FSCM:

Figure

Carbon

605'72

Page

2-5

25

244-1

TM3MX)

~0~~~8267,

#483

Mic system to pins 3 and 4 of the front-panel

/

Second Edition,

or

LINE

July

PLUG

#

482,

PJ-0518

wmector on the

1989

SECllON

3.1

3:

INTRODUCTION

TECHNICAL

Model

TWU24

OPERATING INSTRUCTIONS

/

TWI222

MANUAL

Interface Units

After making connections as desaii in section

is

the unit

describes how to adjust and operate

installations

system

readjustment may

32

RTS

After making the dons described in don

set

all

to minimum.
system on Establish that both systems are operating

properly.
Plug a carbon miaophone headset into

MIC ONLY jack located on the rear panel.
Increase the GAIN FROM RTS to
Hum into the carbon miaophone and adjust

BALANCE FROM RTS until
obtained.

With

one person
on the &wire system, adjst the GAIN controls
both people

33

RTS

After making

se3

all

GAIN and BALANCE controls on the
to minimum.
Zwire system.
operating properly.

Plug a carbon miaophone headset into the
CARBON-MIC-ONLY jaek on the

ready to

dadbed

is

adjusted, any

TO

4-WIRE

GAIN and BALANCE controls on the

Turn

can

hear

TO

2-WIRE

the

Turn

be

adjusted.

This

each

in

don

part

be

required. minimum.

SYSTEMS OPERATION

power to the RTS and the 4-wire

on

the RTS

each

other clearly.

SYSTEM

comeetions desaid in sectinn

on the

Con6nn

power

2

4

after

of the system changes, Decrease the GAIN FROM RTS control to

the

CARBON

50%.

the.

best null

"rW"

line and another

OPERATION

to the RTS and the

that

both systems are

rear

2

section and adjust

of the

the

2%

TWU24

is

until

22

TWI222

of the

TWI222.

Set the BALANCE FROM RTS control
approximately

Inaease the GAIN FROM RTS control to maximum.

50%.

to

Speak or hum into

the

a null

is

obtained.

Use an RTS user station to listen on the RTS system.

Turn

the

microphone off and volume to maximum.

Increase the GAIN TO RTS to maximum.

Adjust the BALANCE TO RTS control for a null in

the

noise as heard on the RTS system.

Reduce

The

taken not to disturb the balance controls.
improperly balanced interface may oscillate.

Set both

Have

through

person

3.4

After

turn
gain

system on and verify that the system works.
Plug a carbon miaophone headset into the CARBON

MIC ONLY
rack mount versions ('IWKZI-T-RM)

jack

Set the BALANCE FROM RTS control to

approximately

Increase

the

GAIN TO RTS to minimum.

interface

gain

controls to approximately

two people establish two-way communication

the interfaec; adjust

can

be

RTS

TO

2-WIRE

making the wnnections described in section

the

TEE0 HOLD switch off and

controls to minimum.

jack on the rear of the TWIlU-T. On

is

on the front panet

the

GAIN FROM RTS control to maximum.

the

carbon microphone headset

BALANCE FROM RTS control

is

now balanced and care should

25%.

the

gains

so

that each

heard clearly.

TELEPHONE OPERATION

all

level and

Turn

power to the RTS

the

carbon mic

50%.

until

be

An

23,

RTS Systems Burbad,

CA

91506 / FSCM:

Page

60572

3-1

TM3600

/

Seeond Edition, July

1989

TECHNlCAL

Model

TWIZ24

Speak or hum into the carbon microphone headset

and adjust the
a

null

is

BALANCE

obtained.

FROM

RTS control

/

until

MANUAL

TWU22

Interface

Units

Decrease the

minimum.

Use

an RTS user station to listen

Turn

the microphone off

Increase the

Adjust

the noise
Reduce the GAIN

The

taken

improperly balanced interface
Set both
Have

through
person

the

as

interface

not to

gain

two

the

can

GAIN

GAIN

BALANCE

heard

is

now balaaced and

disturb

controls to approxhately

people establish two-way wmmunication

interface; adjust the

be

heard

FROM

and

TO

RTS to maximum.

TO

on

the RTS system.

TO

RTS to minimum.

the

dearly.

RTS control to

on

the

RTS

volume to maximum.

RTS control

balance wntrok.

may

for

care

odate.

25%.

gains

so

a null in

ahodd

that each

system.

be

An

RTS Systems Burbank,

CA

91M6

/

FSCM:

Page

60.572

3-2

Seaond

Edition,

July

1989

TECHNICAL

Model

TWI224 / TWI222

MANUAL

Interface

Units

SECTION

4.1

Section 4 deseni how the
wire

43

Figure

eonnebm

4:

THEORY OF OPERATION

INTRODUCTION

models.

FUNCTIONAL Dm-ON

Sedon

4-1

shows the block

at

the lower lett

43

describes

TWI224

the

diagram

LML

works. Section

Telco Hold circuit

of the

TWI224.

CURRENT SOURCE

42

desuibes the circuit

which

is

used

The

RTS

"ZW"

5mAfiOLT

RING

GAIN TO

as

used

in

the TWI222-T and

intercom

LEVEL

RTS

comects to the

in

both the We and

TWI222-T-RM.

XLR-3-31

'A

XLR-4-31

2-

XLR-3-31 CURRENT SOURCE

RTS

YiE

IN

RACK

AN

XLR-4-32

RTS Systems Burbank,

MOUNT

(-RM)

(MALE).

CA

9U06

TWI224

/

WCM:

(E)

Figure

Block

Page

VERSIONS.

4-1

Diagram

60572

Th9600

4-1

CONNECTOR

/

Second Edition,

July

1s

1989

TECHNICAL

Model

TWI224

Power to operate the intertace
channel

RTS interwm passes through the channel select

switch to
bilateral current source presents a
impedance to
balance pot

This

system.

Next

the input of

output passes through a

bus

current source must

ohms.
impedance to
resistor must

The
wnnedor

LEVEL

ic

input of a bilateral current source. Output from the
current source

input. One end of the BAL4NCE control wnnects to
the input while the other end connects to the output

Thus

of-phasc output
return to the &Wire system
return to the &Wire system would mean too much
sidetone on the
does not affect sidetone on the RTS system.

1.

Audio from either channel

the

output of a biieral current source. The

the

RTS line.

and

sent to the LEVEL FROM RTS pot.

control sets the level going to

an

ic

provides

another

of the external 4-Wire system. The output of

If

the external interwm does not present

be

4-wire

passes

TO RTS pot. The output of the

amplifier with a

at

some point in the middle of

20

the

4-wire

used.

input of the front-panel

through a

is

inverted when compared to the

will

Si

dB

of

biikteral current source. The

1:l

be

terminated
output, an external

gain

of

cancel

the input such that the

is

4-wire

system. The balance control

is

derived from

1

or

high

is

picked off

the

external

gain.

This

signal feeds

transformer to the talk

with

100

1:l

transformer to the

pot

20

dB.

This

the

pot the out-

miaimizcd.

Too

/

2 of

the

input

of

the

4-wire

this

to

400

this

200

ohm

-431

feeds an

feeds the

much

TWIZ22

MANUAL

Interface

Power for the interface

a

special regulator circuit.

Audio from RTS passes through the BALANCE
FROM RTS pot to the LEVEL FROM RTS pot.

The

signal

This

feeds the bilateral current source.

Output from the current source drives

wire

interwm through a

is

inverted.

The BALANCE TO RTS wntrol wnneds to both
the input and

the pot
cancel. It
null or feedback

Input from the external 2-wire interwm enters the

TWIZZL

signal

The

LEVEL

RTS system.

ampli6er. Output from
bilateral current source
RTS line.

Again

signal wming from

feedback oscillation
The test headset jack

the RTS line
the external interwm

able to speak to, the person

Units

is

derived from channel

is

then amplitied

the

inverted output. Near the center of

is

a place where the out-of-phase signals

is

important to set the balance wntrol for

will

occur.

through the front-panel

is

picked off of the BALANCE TO RTS pot.

TO

RTS pot sets the level going to the

20

dB

the balance wntrol must

the

will

with

a carbon-mic headset. Persons on

20

dB

by

an

ic

amplifier.

the

external 2-

kl

transformer.

of

gain

is

provided by

the

amplifier feeds another

which

provides oulput to

be

external interwm system or

result.

is

connected to talk and listen to

will

not hear, nor

using

the test headset.

This

output

XLR43L

set to null the

will

they

1

with

The

an

will

i.c

the

be

a

The test headset wnnedor provides a wnvienent way

to balance the system. It

listen to the RTS system, with a carbon-mic headset,

just

as

if

it were another station on the 4-wire system.

43

lWEl2

Fwe 4-2
similar to the

wntrols and only one transformer.

BLOCK

is

the block

he

RTS Systems Burbank,

is

wnneeted to tak and

DESCRIPTION

diagram

except there are two balance

for the

CA

TWI222

91506 / FSCM:

It

Page 4-2

4.4

CIRCUIT DESCRIFTION

This

section describes the circuit operation of the

TWIZL4.

power

power
wall-plug transformer

The power supply of the

from channel 1 of

(LP)

is

CR2

provides reverse current protection while

acts

as

a

fuse

catastrophic unit failure.

60572

TM36Ofl/

lWIZ4

the

RTS line except for local

units

which

derive

with

on severe overvoltage conditions or

Sewnd Edition, July

their

an output of

derives its

power from a

14

volts dc.

1989

R30

Model

TECHNICAL MANUAL

TW1224

/

TWU22

Interface

Units

RTS

XLR-3-31

3

RTS

-7

CHANNEL

SELECT

+*

IN

RACK MOUNT (-RM)

AN XLR-4-32 (MALE).

CURRENT SOURCE

+12

1

REGULATOR

(E)

LEVEL

WIN

20db

A

TO RTS

A

'4

CONNECTOR

VERSIONS, CONNECTOR IS

RTS

Systems

Burbank,

CA

TWU22

91506

/

FSCM.

Figure

Block

60572

Page

4-2

Diagram

4-3

TM3600

/

Secnnd

Edition,

July

1989

TECHNICAL

MANUAL

Model

4A

CIRCUIT

VR2

proteds the unit from excessive line voltage

shunting anything over
voltage spikes
unplugged from the RTS line at once.

The output of U2
U2 should read

output (0)

C25

slows down the current response. of U2.
keeps the input to U2 a
does not "short out" the audio on
provides filtering.

Q1

is

provides
filtering.

Audio from the RTS intercom enters through the

rear-panel

C20

and

of the capacitance.

C20

and
pass low frequencies. If they did not, the output level
of the bilateral current source would go up and
circuit would bceome unstable.

DESCRIPl'ION (continued)

36

volts to ground.

can

occur

when many user stations are

is

set

for U volts

12

volts between

terminals.

high

impedance so that it

the

a constant current source to

6

volts to

XLR-331 (lower

(29.

C29

bias

the

op amps.

left)

and

These

capacitors are large because hal£

is

lost

by

their bipolar arangement.

must

also

be

large because they must

TWI224

by

R32 and

the

adjust (A) and

RTS line.

VR1

C28

is

decoupled

/

TWIm

by

High

R31.

This

C26

which

provides

by

the

Interface Units

The

signal

continues through
through the wiper. RllA
the signal through
amplifying stage

U1

is

designed to operate with a bipolar power
supply. By biasing the inputs to
operate on

biasing

Ulb

is

feeds the external intercom through
with the
with

connected for k2 step up.
low frequencies.

Audio from the

(upper right) to Ulb, the output of a bilateral current
source. From
RTS) it
it joins

TWI222.

keep the circuit stable.
Uld

is

the current source that feeds the RTS line.

_&

is

done

another bilateral -nt source whose output

-CM

a 200:8 transformer.

passes

RZSA

R29

has

a gain of 10 (20 dB).

C7

to U1.

with

a gain of 10 (20 dB).

single-ended

by

R10 and

(carbon mic) option,

extemal

the

wiper

throd

(lower

and CU roll off

C30,

right). T1

R23,

C18 and RllB

(GAIN

intercom enters through

of

FROM

This

part of U1

+6

volts, the i.c

+

12

volt supply.

the

6

volt source.

T2.
T2

-T

(Telco) units have

CL

is

large in order to pass

R25B

(BALANCE

jumps

to

point 18 1 where

is

not used in the

low

frequencies to

This

feeds Ula

RTS) sends

is

For units

is

replaced

which

an

can

This

T2

T2

TO

The

signal

continues through C19 to
bilateral current source at
large for the same reason
It

is

there

to block dc from channel belect switch

This

eliminates

The

output of the bilateral current source presents a

high

impedance to the incoming
because a bilateral mnt soum converts a
voltage input to a
"current source". When the input voltage
varying, ie. no input,
In order for

the circuit must follow the voltage variations

in the output
0 volts out). Thus
voltage coming in

impedance and does not load the line.

clicks

varying

the

output current to remain constant,

so

that no current

the

the

RTS Systems Burbank,

the

that

when switching channek.

current output. Hence

the

output current

circuit

output

the

output of

right of

C20

and

R26.

C29

signal.

will

is

drawn

(0 volts in

is

actively following

so

that it

CA

91506

are

is a high

C19

large.

This

varying

is

not

vary.

coming

/

FSCM:

the

is

SL

is

not

=

the

60572

Page 44

TM36Ml

/Second

Edition,

July 1989

Model

TECHNICAL

TWllZQ

/

TWU22 Interface

MANUAL

Units

SECTION

5.1

CHANGING

5:

MAINTENANCE

IMPEDANCE,

APP

NOTE DR-501

(see

following

application

note)

RTS

Systems

Burbank,

CA

91M6

/

FSCM:

60572

Page

TMXXXX

5-1

/

Seumd

Edition,

July

1989

Application Note

SUBJECT

APPLICATION:

GENERAL INFORMATION
SPECIFIC DATA CUSTOMER:

DATE

APP

PAGE

The

your system.

at the input and 200 ohms at the output.
interface to a 200 ohm line.
ohms nominal. In the 50 ohm mode, the interface
100 ohms.

When the interface

ohms.

Should you find that your system
200 ohms, change the TWI-222 or TWI-224 to match your system.
the drawing that applies to the change you want to make.
trace and add the jumper shown.

2/5/80

NOTE

1

impedance of the TWI-224

TWI-222 INTERFACE

&

TWI-224 INTERFACE

CHANGING

F

DR-101

OF

2

Normally, the TWI-224

In

the 200 ohm mode, the unit

IMPEDANCE

is

set

This may be changed to 50 ohms or 800

for 800 ohms,

may be changed to better match

is

built to interface 200 ohms

The TWI-222

will

will

is

handle 100 to 400 ohms.

it

will

some impedance other than

handle 400 to 1600

is

built to

handle 25 to

Find

Cut the

I

WIRE:

2
4

WIRE:

50 OHMS
50 OHMS OUTPUT FROM TWI-224

RTS

Systems

BurbqCA

91M6 / FSCM:

60572

Page

TMXXXX

5-2

/

Second

Edition,

July

1989

1100

Nest

Chesrnul Streel Burbank Calrforn,a 91506 213 843-7022

Application Note

SUBJECT

APPLICATION

GENERAL INFORMATION
SPECIFIC DATA CUSTOMER.

DATE

APP NOTE

PAGE

2/5/80
2 OF 2

TWI-224 INTERFACE

CHANGING IMPEDANCE

=

DR-101

2 WIRE: 800 OHMS

4 WIRE: 800 OHMS OUTPUT FROM !LWI-224

RTS

Systems

Burbank,

CA

91506

/

FSCM:

60572

Page

TMXXXX

5-3

/

Second

Edition,

July

1989

TECENICAL

MANUAL

SECTION

This

four sections: shipping
following the description of a part

62 HOW
Parts may
RTS Systems

1100 W. Chestnut Street
Burbank,
818-5666700

63

6:

LISTS

section

umk

TO

be

obtained

CA

91M6

SHIPPING

OR REPLACEABLE PARTS

parts

lists,

and instruetiom

list,

final

OBTAIN PARTS

LIST

dLedly

-

from Customer Service, RTS Systems:

TWD24

Model

assembly, back panel and printed circuit board

is

lWIZZ4

the manufacturer and the

/

TWI222

for

ordering replacement parts. The parts

Interface

manufacturer's

Units

assembly.

part

number.

lists

are divided into

Immediately

rn

L

1

63.1 SHIPPING

1
1

6A

DESCRIPTION
Model

Model
Instruction

FINAL

DESCRIPTION
Washer, Teflon Swtrom

Saew 8-32 x 112" lWe Flat
Pot, Audio
Pot, DL lOK/lOK

Transformer, Audio Boa
Knob,

Knob,

TWI224

Instruction

TWll22

ASSEMBLY

Cap, .Oluf/lKv

#73

Shield Bead Fairrite 2673OLW1

Sii

Dual

Interfaw

Manual

LIST

-

Interface

Manual

Taper

C.D.

Blk 114"

Blk

lWUZZ

-

lWIZ24

10K Bourns 8lAlA-BsDl5

"CP"

1/4"

(W10-2195-00)

561237-40

HD

AB

26M9U7

Use

l51ORlU32R

LM9003

Alco

K700B

Ah,

K5700B

Phil

NKL

PL ST

RTS PART NUMBER

RTS

PART NUMBER

RTS PART NUMBER

RTS Systems Burbank,

CA

91506

/

FS(3M:

Page

60572

6-1

TM3600

/

Second Edition,

July

1989

6.5

BACK

PANEL ASSEMBLY

Model

-

'IW12U

TECHNICAL

TWI224

/

/

TWU24

TWI2ZZ

MANUAL

Interface

(9020-178800)

Units

DESCRIPTION
Washer, 378ID, 6WD, Switchaaft S10451

Nut, Hex Kep
Nut, Hex, 318"

4-40

Screw

Cap, Mono .luf/50v

Conn.

Carbon

Cone

3

Corn

3
Wq 24AWG, blue vinyl, stranded,
Wue, 24 AWG, black vinyl, stranded,
Wire, 24 AWG, brown vinyl, stranded,
Wue, 24 AWG, red vinyl, stranded,
Wire, 24 AWG, green vinyl, stranded, 9
Wue, 24 AWG, blue vinyl, stranded,
Back Panel, STD BP/TWI Per FAB 1511-1 / FD23l9

6.6

FRONT PANEL ASSEMBLY

DESCRIFTION

Lug, Solder #4 Smith 14144
Nut, Hex Kep
Nut, Hex 318" 1007-000300
ScrewWx3/8" lOode.FLHD, C/R,BRWHZinc 1008-4012-00

Switcb, Toggle, SPDT Alco MTM-106DPC

Conn.

4
Wue, 24 AWG, blue vinyl, stranded,
Wire, 24 AWG, brown vinyl, stranded,

22

Wue,
Dress Nut Stain
Front Panel

4-40

x

318" lOOde

Mic.

Pi

male Neutrilr NC3MP

Pin

Female

4-40

Pi

Female Cannon

AWG, Buss 100 roll, Belden 8021

TWI2ZZ

FL

HD,

.1

Spacing, 1" length

Switchaaft MNl14B

Hirase

Fi

-

IBT

/

TWI224

HA16PR-3S

1WU22

AXR

W-NU-17A

FAB DWG U75, FD2181 9070-2181-00

C/R, BR WH

3"

3"

9"

9

9"

/

l%'J224

4-31

5"

5"

318"

O.D.

RTS PART

zinc

(9020-219300)

PTS

PART

NUMBER

1006-0031-00

1007-0001-00
1007-00M00

100&4012-00

1511-R104-21

mu-oao2~

m~-ccm-oo

mi&M)36oo

25ll-0001-00

2.511-0002-00

2511m

2511-001560
2511-001800
2511-004200
9080-2319-00

NUMBER

100UXX)4a0

1007-0001-00

m3-0106-PC

2018-0001-02
2511-0005-00
2511M)06-00
2512-OM2-00

2709-000300

6.7

PRINTED

DESCRIPTION

Teflon Sleeving
2
7 Res.
7 Res.
4

1
1

Res.

Res.
Res. CF 11K ohm 1/4w 5%
Res.

CIRCUIT

CF

100 ohm 1/4w

CF

1K

CF

l00k ohm 1/4w 5%

CF

l00K ohm 1/4w 5%

CF

12K ohm 1/4w

RTS Systems Burbank,

ASSEMBLY

20

AWG Alpha

5%

ohm 1/4w 5%

5%

-

CA

1WU22

TFT

9-

/

IwIu4

200-20,

/

FSCM:

Page

Roll

60572

62

(9030-2196-02)

PTS

PART

'I'M3600

/

NUMBER

Second Edition,

July

1989

6.7

PRlN'IED

Model

CIRCUIT ASSEMBLY

TECHNICAL MANUAL

TWIVa

-

'LWU22

1

TWU22

/

lW'I224

Interface

(9030-219602)

Units

DESCRIPTION

Res.

CF

2OK

ohm

1/4w 5%

Res.

CF

22K

ohm

1/4w 5%

Res.

CP

22

ohm

1/4w 5%

Rcs.CF36ohm1/2w5%

Rw

CF

33

ohm

1/8w 5%

RW.

CF

470

ohm

114~ 5%

Rw

CF

4.7K

ohm

1/4w 5%

Cap,

.Oluf/lhr

Cap,

szOpf/lKv

Cap,

Mono

Cap,

Elec

Cap,

Elec

Cap,

Elec

Cap,

Elec

Cap,

Elec

Cap,

Elee

Cap,

Elec

Cap,

Mylar

Cap,

Mylar

Diode,

Diode,

Diode,
Diode,
Transistor,
Voltage Regulator, National

1.C-

I.C.

Transformer, Audio Bourns
Wire,
PCB,
Insulator
Natural Rubber

Outside

Ext.

Extrusion, Belt Pack
Outside

lN914B
IN4004 1 Amp,
lN5233A
lN5365B

MQ403P Motorola

Socket,

22

Ccm/m

Case,

C.D.

Ccr

.luf/50v
1m/16v
lOuf/lbv
lOuf/Mv

lOOuf/lOv
lM)Uf/Mv

2.2uf/Mv
47uf/l6v

.001uf/loOV
.0047/100V

Si

Voltage Regulator

Zener

J305

Siliwnix

14

Pin

AWG

Buss

FAB

w/out

holes

.062"

Profegsing

TWU22/224

Processing

Use

1510R1032R

Di

Radial

.1

spa*

Axial

Radial

Radial

Radial
Radial

Radial

Radial

Radial

WV

Voltage Regulator

Bmdy

1W

Roll, Belden

Per

FAB

Thick

Insulator

Per

6'

x

3

TWU22/224

1

length

10%

LM317MP

DU14P-108

LMwCn

Dwg

13nlAW2032

Per

Dwg

1840

x

3'

Wide

w/out

hole

Dwg

1802@D2318

112"

x

1

314"

Case

8021

RTS

PART

NUMBER

RTS Systems Burbank,

CA

91506

/

FSCM:

Page

60572

Th43bO4 / Second Edition,

6-3

July

1989

68

FINAL

ASSEMBLY

DESCRIPTION

-

TWlZ22

TECHNICAL MANUAL

Model

TW1224 / TWI222

(9010-2lS4-00)

Interface

RTS

PART

Units

NUMBER

2

8

2
4

2

Washer,
Saw

8-32

Pot,

DL lOK/lOK

Y73

Shield

Knob,

Teflon

Dual

Seastrom

x

112"

loode

Bead

Fairrite

Blk 114"

5612-37-40

Flat

HD

Phil

NKL

PL

ST

"CP"

AB

26M907

26m1 24W-0001-00

Alco,

K5700B 270Z~B

1006-004400

10088031-M)

1407-

RTS

Systems

Burbank,

CA

91506

/

FS-

pago

60572

6-4

Th9600

/

Second

Edition,

July

1989

SECTION

Document

N!mkz

7:

DIAGRAMS

Model

TECHNICAL

TWI224

/

TWU22

MANUAL

Interface Units

SDl255
ASl38l
MU79

EN#l38

mu67

EN#DR-500

ENXDR-m

SD1240

AS1241

APN#CN02

APNXCNUZ

APNBcN03

APN#CN03

SD1635
AS1762

SDl25S

Schematic Di, Intercom Interface
mbly Diagram, P.C.B.
Assembly Diam, P.C.B.

Fqheering Note, TWI-SKMDCU Interface

Wiring

TWISK70-DCU,

sheet

Schematic

Assembly

TWI-SK7&DCU, Squelch Circuit

sheet 2 of 2
TWISKMDCU Squelch

sheet

Schematic Diam, Squelch
Assembly

Schematic

Diagram,

2

of

2

Diagram,

2

of 2

Diagram,

TWISK70-DCU Interface

4-Wm

.............................................

Diam, TWISK70-DCU

....

-

.................................................................................................................................

...........................................

Diam,

TWI224

TWI224

Interface

TWI-SKMDCU Layout

Card,

Circuit Description sheet

Mod

P.C.B. Squelch

Intercom Interface

TWI224

Interface
Hold Circuit

W/SAP

--

................................................................................

,

........................................

Piiack

"

.......................................................................................

For TWISKMDCU

Modification

TW1224

........................................................................

Layout

..............................................................

Layout

Card

..........................................................

....................................................................

..............................................................................

1024, sheet 1 of 2

Chart

-.,."

Board Installation to Interface Card

...................................................

-

.....

.......................................

.......................................................

1

of

2

.............................................

..........................................................

For TWISK70-DCU Layout

...-...........-.

.......................................................................

..............

7-2
7-3
7-4
7-5

7-6

7-7
7-8

7-9
7-10
7-11
7-l2
7-l3
7-14
7-15
7-16
7-17

RTS Systems Burbank,

G4

91506

/

FSCM:

60572

Page 7-1

TIU3600

/

Second Edition,

July

1989

RTS

Systems

Burbank,

CA

91W)6

/

FSCM:

Page

60572

7-2

TM3i%l/

Second

Edition,

July

1989

Model

TECHNICAL

TWI224

/

TWI222

MANUAL

Interface

Units

NOTES:

RTS

3.

@

@

2.

C3\

I.MSUED

Systems

Ql,A5

EARLY

NOT

ON

-RD;

LINES INDICATE

Assembly

Burbank,

SHDWN,

VERSlONS;Ql,

IS

FCR

Dii,

CA

91506

J305

FUTURE

RM

/

FSCM:

(70-92

15

El05

USE.

ON

P.C.B.

Page

CASE)

(TO-IB

DOTTOM

TWI2.24

60572

7-3

PIN

CIRCLE)

Or

-0.

Interface Layout

'I'M3600

/

Second

Edition,

July

1989

TECHNICAL

Model

~~1224

/

TwI222

MANUAL

Interfaffi

Units

RTS

Systems

CAM6104 X480-2970-02-03-00 SWAGE MD SOLDER PINS

BEFORE JNFFING

LAMP VPE
T- 1314

PARTY
APPLY
HOLD THEM IN PLACE.

NOTES

:

Assembly

Burbank,

THE

P.C. BOARD.

17M

:

28V,

W/RE

LEAD LAMP.

579

-17&4.

A

DROP OF CLEAR SILICON TO LAMP BASES TO

Diagram,

CA

91506

P.C.B,

/

FSCM:

.04A 34MSCP,SK IIR.,/NCANDESCENT

MOUNT LAMPS FLAT AGAINST RC.MIARD.

h,

1WI224

60572

Page

Hold

ThEWO

7-4

MOUSER ELECTRONICS

Circuit

/

Second

Layout

Edition,

July

1989

__

4-

1100

Engineering

West

Chestnut

Note

Street.

Burbank Calrlornra 91506 213/643-7022

SUBJECT:

-

CARD

DATE:

TWI-SK7O-DCU INTERFACE

07-14-78
CUSTOMER: ALL USERS
ENGINEERING NOTE
PAGE:

1

of

2

#

:

138

OPERATION

SET-UP

1)

ISO/NORMAL switch to NORMAL.

2)

BALANCE control to center of range.

3)

Both GAIN controls to extreme counterclockwise position.

-

4) Plug in a carbon mic or Plantronics type headset into
the headset jack.

5)

Advance GAIN controls to approximately 1/3 of maximum

setting.

6)

Switch on microphone, say ahhhh and adjust BALANCE for
null in headphones.

7)

Move carbon mic headset plug to DCU "AUX" (INCOM) module.

8)

Set Headphone gain on "AUX" module midway. Set GAIN
controls on interface so that you and a person on the
RTS line can hear each other well.

9)

Vertify camera position can talk well with RTS line

(RTS belt pack gains set for normal two-way conversation

on RTS line).

ADDITIONAL COMMENTS

If there is distortion, check INCOM level settings in

Hitachi process pack.

The test jack in the interface module talks to the RTS

line but not the camera. Use the jack in the "AUX" module
to talk to the camera, and to talk to the camera when the ISO/
NORMAL switch is in the IS0 position.

RTS

System

~urbank,

CA

91506

/

FSM:

60572

Page 7-5

Th9600

/

Second

Edition,

July

1989

Model

TECHNICAL

TWI224

/

TWI222

MANUAL

Interface

Units

CHROMA

KEY/RGB

J

13

HITACH1

REAR

DCU

VIEW

+

OUTPUT

AUX

("INCOM'

CARD

J9

CARD)

PLUG

INTO

RTS

THIS

RTS

CARBON

INTERFACE

SOCKET

Systems

Burbank, CA

EST.

Wiring

MIC

TEST

Diagram,

91506

/

4

WIRE

JACK

TWISK70-DCU

FSCM:

60572

Page 76

INPUT

Interface

TM3600

/

Second Edition,

July

1989

1100 West Cheslnut Street

Burbank

Calrfornra 91506

213

843-7022

Engineering

SUBJECT

TWI-SK'IO-DCU

Note

4 wire interface with the SAP 1024

DATE
CUSTOMER

ENGINEERING NOTE

PAGE

For operation in the 4

to be converted to 4

01/29/80

1

of

2

=

DR-500

wire.

wire

mode.

the TWI-SK70-DCU card needs

To do this, move the zero-ohm jumper

shown below. Remove the jumper that goes from the balance pot wiper

(R15) to the

shown to the

y

0

#

L

0

GAIN

HI

ope

0%

r3"s-t

FROM

side

i

RTS pot (R16

of

Rl6.

HI).

--

Add

a

wire

from the point

--

om-

*-wk+s

-M

"=ul;.sr

To

KIL

YI

i

rrreO

.=,-0

"<

"8

r---q

L--->

Our-

Our-

0
Ou~cn
0

-0

01,.

;

I

a

DWb.

UJ%%I

ASIZ4I

0

0-

0

r3

-

"

n

)D

Y

Y

Q

I.

a.

RTS Systems

Burbank,

CA

91M6

/

FSCM:

Page

60572

7-7

TM3600

/

Second

Edition,

July

1989

1lJLl

vt'es,

Cnesfnof Sfreef

Burbank

Cal#tarn8a

9';J6

2'3

8J3-7022

Engineering

SUBJECT

WI-SK7O-DCU

Note

4 wire interface with the SAP 1024

DATE.

CUSTOMER:

ENGINEERING NOTE

PAGE:

01/29/80

2

of 2

=

DR-500

For optimum performance with the SAP 1024, transformer T2

should be changed to a Bourns LM9001.

Terminate T1 with 430 ohms.
Also terminate the incom out with 430 ohms. To increase the gain,
up to 600 ohms may be used. To reduce the gain, as low as 100 ohms

,-

!

may be used.

Iru4.

sb

IelO

1151

a

-...--".7

-0-

."

I

IWML

ill-a"

Adjust the

is

the same

as

Adjust the
provide about
connector.

GAIN

FROM RTS pot so that the level on the RTS line

that of a regular user station.

GAIN

2

FROM RTS to about 1/4 of maximum. This should

volts peak to peak

signal

The levels in the SAP should be

The balance control no longer has any affect.

RTS Systems

Burbank,

CA

91M6

/

ESCM:

Page

60572

7-8

TM3600

at

pin 20 of the edge

set

for maximum gain.

/

Second

Editioq

~dy

1989

TECHNICAL

MANUAL

Model

TWU24

/

TWI222

Interface

Units

RTS

Systems

Burbank,

Schematic Diagram,

CA

91506

/

FSCM:

Page

IWISK70-DCU

60572

TM3600 / Second

7-9

Edition,

July

1989

Model

TWI224

TECHNICAL MANUAL

/

TWI222

Interface

Units

lil

NOTES:

RTS

OnJUMPERS

OPTION

\L

Systems

I.

Assembly

Burbank,

CA

91M6

Diagram,

/

FSCM:

IWI-SK70-DCU

60572

TM3600

Page

7-10

Layout

Chart

/

Second

Edition,

July

1989

I

loo

Wesr Cleslnul Street

Application Note

Burbank

Cal~fornla 91506 213

843

7022

SUBJECT

INSTALLATION TO INTERFACE

APPLICATION

GENERAL INFORMATION

SPECIFIC DATA CUSTOMER.

DATE
APP NOTE
PAGE

The TWI SK70
for use on the RTS
058 and 51901-51950).
by the
the RTS PL/Intercom lines to remain operable and noise free.

mount the piggyback board, and five
board. One zerohm jumper
board. The trimpot on the squelch card controls the sensitivity of

the squelch.

DCU

Two mounting holes must be drilled into the main board to

TWI SK70 DCU SQUELCH CIRCUIT PIGGYBACK

CARD

TWI-SK7O-DCU

4/15/80

F

CN02

1

of 2

DCU

squelch circuit' piggyback board

TWI

when the

SK70

camera

Its

DCU

INTERFACE CARD

purpose

is

disconnected from the DCU and to allow

is

to

attenuate noise generated

wires

is

to be removed from the main interface

(serial

connect

it

BOARD

is

intended

numbers 001-

to

the main

The complete installation

1.

Place the main board, component side up. card edge fingers

pointed to the right.

2.

Drill

hand edge and 2.00 inches from the near edge

0.156 diameter hole
inches from the near edge. Accuracy

avoid interference with components on the main board or the card
guides.

3.

Using 4/40 hardware. and extra nuts
bring the
the squelch card (component side up) on the
securely, making
that the card caqe guides

4. Remove the zerohrn jumper, which, on the main board,

between pin 22 of the card edge fingers and

the

screws

first

up from the solder side of the main board, and mount

0.156 diameter hole 2.00 inches from the left

is

placed 4.00 inches from the left and 0.75

sure

that no

will

is

outlined below:

of

the board. The second

is

very important in order to

to

act

as

short stand-offs,

main

wires

not hit the piggyback squelch card.

are

pinched under the card and

R-1

(GAIN

card. Fasten

is

connected

TO RTS)

.

RTS

Systems

Burbank,

CA

91506

/

FSCM:

60572

Page

7-11

TFu13600 / Sewnd

Edition,

July

1989

SmS

1100 -sf Chestnut Sfreet Burbank Ca,tlornta 91506 21.3843-7022

Application

SUBJECT

TO

INTERFACE

APPLICATION.

GENERAL INFORMATION
SPECIFIC DATA

OATE.

APP NOT

PAGE.

5.

Wire as follows: (see drawing no. 1869)

lcir&

1

2 from pad marked
3 from pad marked "GNDW to pint2 or pint44 (wire
4 from pad marked "+9" to CRZ, cathode

TWI SK70 DCU SQUELCH CIRCUIT PIGGYBACK BOARD INSTALLATION

CARD

TWI-SK~O-DCU

4(15/80

F

.

2

cN02

2

from pad marked " INn

Note

,

CUSTOMER:

board

mam

to pint22 (use pad formerly
occupied by zerohm jumper)

"SWn to R1 (use pad formerly

occupied by zerohm jumper)
to zerohm jumper)

board

5

6.

Adjust the trimpot on the squelch card fully counterclock-wise for

maximum sensitivity.

turn the
interface card.

from pad marked "-9" to CR3. anode

If nuisance triggering of the squelch occurs,

trimpot clock-wise as needed. No adjustments are needed on the

RTS

Systems

Burbank,

CA

91506

/

FSCM:

60572

Page

7-12

TM3600

/

Second

Edition,

July

1989

*

llGL'

lvesr

Cnesrnur

Srreer

Burbank

Cal,forn,a

91506

213

843-7022

Engineering

SUBJECT.

DATE:

CUSTOMER:

ENGINEERING NOTE
PAGE:

This squelch circuit solves the following field operation
problem of the SK 70
disconnected and moved, carrier
noise
circuit, noise from the camera
normal PL/Intercom operation to continue. Circuit operation
depends both on the differing amounts of energy in noise and speech,
and the distribution of this energy in the frequency spectrum.
Generally. speech
kilohertz while the
to twenty kilohertz. The squelch circuit utilizes this principle
by sensing high frequency high level noise then disconnecting the

DCU

the
enabled with a very short delay.
communication network

is

from the PL/Intercom system. When the camera

DCU,

WI-SK70-DCU SQUELCH

4/15/80

=

CN03

1

of

2

injected on the PL/Intercom line. With the squelch

will

DCU

the noise disappears and the PL/Intercom to the camera

is

Note

CARD,

DCU:

when the camera/process pack

is

not have any significant energy above five

will

unaffected.

generate uniform noise from

During this

CIRCUIT

is

lost at the

greatly attenuated, permitting

DESCRIPTION

DCU

and receiver

reconnected to

is

time,

the

100

rest

hertz

of the

is

is

An

input RF bypass capacitor reduces the possibility of
overload and false triggering of
contains an active second order bandpass filter
kilohertz) which removes speech energy below

RF

spurious

the signal that filters through. The input to the schmitt trigger

is

biased by the negative supply to ensure that the squelch
when no signal
means of a
and entire
compromising the sensitivity of the trigger. Notice that up to this
point, all the circuitry
currents and voltages are blocked and are not added to the signal.
This allows for
cumbersome nulling techniques. Also, the impedances used in the

circuit are chosen to minimize the effects of variations in

different integrated circuits so that all results are highly

repeatable.
voltage to a
occasional high frequency bursts from musical sources. Thus, only

noise above 100 kilohertz.

is

present. This negative bias can be adjusted by

10k

RTS

trimpot and

circuit

a

A

rectifier and

CMOS

Systems

Burbank,

without changing the filter hinge points or

highly sensitive circuit without expensive and

analog switch. The integrator filters out

CA

sets

is

a.c. coupled so that all offset and bias

91506

the threshold of the schmitt trigger

RC

/

FSCM:

Paac

the

integrator provide a

60572

7-l3

circuit.

A

schmitt

TM3600

/

Second

The next stage

(5

kilohertz to 100

5

kilohertz and

trigger squares up

Edition,

D.C.

July

control

1989

is

RF

off

Engineering

Note

SUBJECT

DATE:
CUSTOMER:
ENGINEERING NOTE

PAGE:

TWI-SK7O-DCU SQUELCH CARD, CIRCUIT DESCRIPTION

4/15/80

=

CNO3

2

of

2

DCU audio noise with a high statistical probability of high
frequency components will trigger this circuit. The CMOS switch

will normally pass the signal until the control voltage directs the

switch to open the signal path and shunt the input of the op-amp
going to the PL/Intercom lines to ground. This scheme provides as

much attenuation as possible.

It is hoped that this note has given the reader an

understanding of both the basics of this circuit as well as some of

the major details of the design.

RTS

Systems

Burbank,

CA

91506

/

FSCM:

Page

60572

7-14

TM3fjOO

/

S~econd

Edition,

July

1989

el

-

==

INTEGPATOR

4

RECTIFIEP

1/50

-

-

-

I

8

WITHOUT

-DCU.

MEASURED

TKiL-SKlO

D.C.,

FOP MOUNTIN$ TO

.

MClA053BE.

oR

WATT,*^%

I/&

FILM,

SHOWN: MICEOFARADf /VOLTS.

ARE

CAPEON

LF353 ;UZ=CO4053hE

APE

oa

VALUES

lWISK70-DCU

ACTIVE BANDPASS PlLTEP

DWQ#le(oq

SEE

(r

S0\16I. FOP CONNECTION TO TWI-5+10-DCU.

iNESS3Z

ALL PEFERENCE VOLTAGES APE

5.

Ul

INPUT, UNLESS NOTEO.

3

4,SEE

CAPACITANCE

I. ALL RESISrDffi

NOTES: UNLESS OTUEPWISE SPECIFIED

2.

Z.5V(S.OV

For

Mod

Schematic Diagram, Squdch

ON

TO 'IN'

ON

'SW'
TO

Model

TWI224

TECHNICAL MANUAL

/

TWU22

Interface

Units

Assembly

RTS

Systems

Dim,

Burbank,

CA

P.m.

91506

Squelch

/

FSCM:

Modification

60572

Page

7-16

For

TM3600

IWI-Sg70-DCU

/

Second

Edition,

Layout

July

1989