Telex BTR-200 User Manual

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Table

of

Contents

Page

Chapter

General Description
Specifications BTR-200
Controls and Connections 1-2

Front Panel 1-2
Rear Panel 1-5

1

1-1
1-1

()

Chapter

Audio Boards ......•.................................................................................................................................... 2-1

Receive Board 2-2

Transmit Board 2-3

Chapter

BTR-200 InstrumentDisassembly 3-1
Transmit Board 3-2

Circuit Descdption 3-2
Alignment Procedure
Voltage Tables - TransmitBoard (878521) 3-3
PCB Transmit Assembly (878521-*)(palts List) ; 3-7

Receive Board 3-9

Circuit Descdption (PCB 70714000) 3-9
Circuit Descdption (PCB 750309)) 3-9
Alignment Procedure 3-10

Voltage Tables - Receive Board (70714000) 3-14
Voltage Tables - Receive Board (750309) 3-15
PCB Receive Assembly 878522* (Parts List) 3-21
PCB Receive Assembly 878662* (Parts List) 3-24

Audio Board

Audio Board Circuit Description 3-27

Alignment Procedure 3-29

2 - IdentificationofCircuit

Board

Revision

and

Version

3 - Transmit, Receive & Audio Circuit Boards

: 3-2

Receive Board (70714000) 3-10
Equipment Required 3-10
Receive Board (750309) 3-11
Equipment Required 3-11

,

Receive Expanders 3-27
MicrophoneAmplifier 3-27
Auxiliary Input Amplifier 3-27
Intercom Driver 3-27
Intercom Input. 3-28
Headset and Speaker Amplifiers 3-28
Transmit'Mixer and Filter 3-28
Auxiliary Output· 3-28
Remote Transmit Circuit 3-28
Power

Equipment Required 3-29

Supply 3-28

::

3-27

-i-

Page

Chapter3·Transmit, Receive & Audio Circuit Boards (Continued)

Audio Board Continued

PCB Audio Assembly (878520) Versions 1 thru 6 (Parts List) 3-45

Display Board 3-48

PCB Display 878519 (Parts Lists) 3-48

Figure

1

2

3

4

5

6

7

8

9

10

II

12
13
14

15
16

17A

17B

18

19
20
21

22

23
24
25
26
27

28
29
30
31
32
33
34

List

of

Illustrations

Description Page

Headset XLR Connector Wiring 1-2
Front Panel-BTR200
Rear Panel - BTR-200 1-4

of

Location
LocationofRev Level for Versions 3
LocationofRev Level for Versions I and 2 (Receive Board) 2-2
Location
Exploded View - BTR-200 2-4
Transmit Board Component Layout (Foil Side) 3-4
Transmit Board Component Layout (Component Side) 3-4
Schematic Diagram Transmit Board - Version 1 3-5
Schematic Diagram Transmit Board - Version 2 3-6
Schematic Diagram Receive Board 3-16
Receive Board Component Layout (Component Side)

Versions
Schematic Diagram Receive Board Version 2 (750309) 3-18
Receive Board Component Layout (Component Side) Version
Receive Board Component Layout (Foil Side) 3-19
Receive Board Component Layout (Component Side) Version 2 (750309) 3-19
Schematic Diagram Receive Board Version
Block Diagram Versions 1 and 2 3-31
Block Diagram Versions 3
Audio Board Component Layout (Component Side) Versions land 2 3-33
Audio Board Component Layout (Foil Sde) 3-34
Schematic Diagram Audio Board Version
Schematic Diagram Audio Board Version 2 3-36
Details
Details
Audio Board Component Layout (Component Side) Version 6

with Detailed Areas Showing Differences ofVersions
Audio Board Component Layout (Foil Side) Version 6 3-40
Schematic Diagram Audio Board Version 3 3-41
Schematic Diagram Audio Board Version 4 3-42
Schematic Diagram Audio Board Version 5 3-43
Schematic Diagram Audio Board Version 6 3-44
Display Board Component Layout (Foil Side) 3-48
Display Board Component Layout (Component Side) 3-48

Rev Level for Versions 1and 2 (Audio Board)

thlU

6 (Audio Board)

of

Rev Level for Versions I and 2 (Transmit Board) 2-3

I and 2 (70714000) 3-17

1..

I (750309) 3-20

thlU

6 : 3-32

I 3-35

of

Board Differences Between Versions I and 2 3-37

of

Board DifferenceinVersions 3, 4,5,and 6 3-38

3,4,5,

and 6 3-39

1-3

2-1
2-1

3-19

-11-

: -

')

GENERAL

The BTR-200 is a base station which communi-

cates with up to four portable units simultaneously,
in

full duplex.Itmay be used alone with a headset

or

interfaced

hardwired intercom system.

DESCRIPTION

to

other

equipment

CHAPTER 1

such

as a

n

1-1

CONTROLS

and

CONNECTIONS

Power

ON/OFF

FRONT

Switch: Push this switch once

PANEL (Refer to Figure 2)

to
turn power ON; push it againtoturn the power
OFF.

Power
illuminated when the Power
pushed in the

ON

Indicator:

The Power ON Indicator is

ON/OFF Switch is

ON

Position. It remains illuminated

while the Transceiver is on.

Local

Headset

Connector: 4 Pin XLR Connector
for InputJOutput. The headset jack will accept 6
different Telex Model Headsets. Compatible with
otherintercom headsets with four pin XLR connec­tors that are wired as shown in Figure

MICROPHONE
GROUND

1.

Local Headset Volume: Adjusts volume

to

Local
Headset. DOES NOT AFFECT MICROPHONE
GAIN.

Mic

On-Push-to-Talk/Lock-to-Talk

Switch:
Enables the local headset microphone audio func­tion. NOTE: DOES NOT control base station RF
transmit.

Local

Push-to-Talk

Indicator:

Will

be

il-

luminated whenever the talk function is on.

Local Microphone

Gain

Control

and

Over­modulation Indicator: A screwddver adjustable
control is provided
local headset mic. This input is protected

to

control the input level ofthe

from
overloads by means of a gain compressor whose
operation

is

signaled by the gain LED indicator.

MICROPHONE
AUDIO

Headset

Figure 1

XLR

ConnectorWiring

BALANCED
AUDIO
OUT

Portable
in the
user of the conesponding portable unit
by others connected

EnableSwitches

"IN"

position, the Enable switches allow the

and

Indicators: When

to

the system. Wheninthe

to

"OUT" position, the respective portable will
muted, but this portable will still be abletohear
other selected remotes and interfaces. The in­dicators normally show the presence
transceiver in use

on

the channel corresponding

of

a portable

that indicator.

1-2

be heard

be
all

to

INTERCOM INDICATOR

27160-8-00I-A

Headset

POWER

ON

INDICATOR

AUXILIARY

PORTABLE CARRIER INDICATORS

I.-.--~

Portabte

Station

Connect--

ENABLE SWITCHES
PORTABLE

TRANSMITTERS

ENABLE

TO

RECEIVE

INDICATOR

I

I

I

~OCAL

I

i

HEADSET VOLUME

8TR-200

1I

. LOCAL HEADSET CONNECTOR

1-3

INTERCOM LEVEL CONTROL

INTERCOM

AUXILIARY

ENABLE

AUXILIARY

ENABLE

SWITCH

LEVEL

Front

CONTROL

SWITCH

Figure 2
Panel-BTR200

LOCAL MIC GAIN CONTROL

MIC

LOCAL

ON

PUSIH-lO-TALKI

PUSH-TO-TALK

LOCK-TO-TALK SWITCH

LOCAL MIC
OVE

RMODULATION

INDICATOR

INDICATOR

27160-B-002-A

Transmit

Anteflna

TRANSM
CONNECTOR

AUXILI

o

IT

ANTENNA

ARY

OUTPUT

AUXILJARY INPUT CONNECTOR

CONNECTOR

Headset

r"=-h

Oyn

Mic

fit

r~l

Cant

1

TRANSMITTER

HEADSET MIC

SELECT

Transmit

Off

Remote

SWITCH

SWITCH

o

Intercom

Input

INTERCOM CONNECTORS

TELEX

Fex

Jack

CO

LSpeaker-l

SPEAKER/LOCAL

COMMUNICA

1.0.

850BTR-200

G~

MONITOR

RECEIVE ANTENNA CONNECTOR

TtONS.

INC.

MADEINU.S.A.

Power

300

rnA

A~'~

o

-------

POWER JACK

SPEAKER GAIN CONTROL

(8

n

MIN.)

Figure 3

Rear

Panel BTR-200

1-4

Ext

Intercom Switch, Level Control,
dicator: This switch enables the wired intercom
interface when "IN", and disables it when "OUT".

RTS

For
and the "OUT" positionischannelB. Ascrewdriver
adjustable control is provided to control the input
level

intercoms, the "IN" position is channel A

of

the wired intercom.

and

In-

Auxiliary Audio
and

Indicator:
Auxiliary intelface when "IN" and "OUT", respec­tively. The functionofthe level control here is the
same as that described for the intercom.

Enable

Theswitchenablesand disables the

Switch, Level Control,

(j

REAR

Transmit
antenna(supplied)
should match connector dot

Receive
antenna (supplied)
should match connector dot

Transmit
operator

the "OFF" position, the transmitter is always off.
This mode may be used
solely
transmitter is always on. This continuous mode is
recommended over the "REMOTE" mode. In the

"REMOTE" position, the transmitter is enabled
only when one or more portables are active.

Headset Microphone Select Switch: This switch
allows the user to select either
Dynamic microphone. This switchi~factory preset
to

DYN Position.

NOTE: All Telex headsets that are used with this
intercom are dynamic type microphones.

Antenna

Antenna

Switch: Slide switch that allows the

to

select oneofthree transmit modes.

as

a monitor. In the "CONT" position, the

Connector: Connect5/8-wave

to

this connector. Antenna color

on

BTR-200.

Connector: Connect 5/S-wave
to

this connector. Antennacolor

on

BTR-200.

if

the base is functioning

PANEL (Refer to Figure 3)

In

an

Electret

or

Intercom
the BTR-200 with a wired intercom system.

Auxiliary
used for 2-way (four wire) input and output to the
BTR-200 or as a simplex input or output. Typical
usesare 4 wire low level intercoms, taperecorders,
public address inputs or outputs, orwhen operating
two BTR-200 units simultaneously.

Power
(supplied) or any filtered 12 to 14
source, or 13.0

Speaker
ternal speaker

Speaker
Adjust the gain control clockwise to increase
speaker gain
speaker gain.

NOTE: Leave setting counterclockwise
speaker is attached.

Connectors: Connections to interface

Output/Input

Jack:

Forexternal AC wall supply adaptor

Connectors:

VDC/300 rnA

VAC

RMS/300 rnA source.

Jack:

Allows the user to connect an ex-

(8

ohms minimum)tothe unit.

Gain

Control: Screwdriver adjustable.

or

counterclockwise

to

decrease

Can

if

be

no

1-511-6

Blank

CHAPTER 2

IDENTIFICATION

REVISION AND VERSION

AUDIO BOARDS

Version 1 and 2 use Rev A circuit boards. The
location for the Rev letteris shown below. Version
2 contains a small circuit board with a switch. See
Figure 4.

AUDIO BOARD

RECEIVE BOARD

....

__

..

~---~_.:

LOCATION
SWITCHBOARD

OF

OF

CIRCUIT BOARD

This board is installed in the holes for C124 and
C125 (see below). Version 1 does not have this
switchboard. For Rev C and higher, the location
for the Rev letteris shown in Figure 5.

o

r--------.

Location

AUDIO BOARD

70723-000 REV A COMP

"'-.

Figure 4

of

Rev Level for Versions 1

••• _

:I.

•

.2"!!2";!!.'!!!.I!.E!..~~_:

and

2

c . .

I U I

a:

I

if

«

I 0 I

0

I 3 I

!Xl

I & I

l-

L_

'"

:E

en

z

«

a:

I-

REV LEVEL LOCATED

.--

UNDER TRANSMIT
BOARD

I

70723-000 REV C

U

I

I

Figure 5

LocationofRev Level for Versions 3

2-1

thru

6

Rev C boards can be either Verion 3 or 4. The
differences are all parts values:

Rev D boards are all version 5.

E boards are all version

Rev
Rev B was not produced.

6.

Version

3
4

The

BTR-200

RIOI

82K 82K

200K

RI03

200K

uses oneoftwo receive boards.

Rl25

6.2K 1.5K

4.7K

Rl30

4.7K

Rl31

1.5K 1.5K

4.7K 4.7K 4.7 8.2K 3.9K 15K 10K

RECEIVE

Rl32

Rl33

1.5K 5.6K

BOARD

750309 COMP REV A

Rl54

Rl62 Rl68

9.lK

68K

Rl70

68K

Cl33

lO~F

22~F

LocationofRev Level

Early production units came with 70714000, and
750309 was installed in later units. 70714000
came in two versions that differed slightly (See

table below):

Version 2 was built only with Rev C boards.

Version 1 was built with Rev A, B, or C boards.
Thedifferentrevisionson this board weremanufac-

turing changes that did not change the schematic.

70714000

Version

1

2

R327

4.7K 4.7K 4.7K 4.7K 10K 10K 10K 10K
10K 10K 10K 10K 20K 20K 20K

R345 R363

Figure

R381 VR302

6

for

Versions 1

750309 Rev

750309 Rev

Some early version 1 boards did not have a shield
over the oscillator section

and

2

Aboards are version

Band

C boards are version

..

VR304 VR306 VR308

1.

2.

20K

2-2

All

Rev

be

version 1or

Aboards

70724-000 REV A COMP

LocationofRev Level for Versions 1

are

version1.Rev Bboards

2:

TRANSMIT BOARD

,.--

--------

I '70"12'

....

-000

rEVAOONP

7--------

Figure 7

may

I

and

2

o

Version R503 R521

1 4.7K 10K

2 15K

68K .001 uF

CS31

.0033uF

2-3

30

(TYPICAL\~e.

BOTH SIDES)

(TYPICAL
4 PLACES)

~.

":

th

31

31

/(TYPICAL

,fj

3 PLACES)

32

DETAILB

10

10-9-12~

"*--/t-'12

(TYPICAL

4 PLACES)

DETAIL A

13

10

--===--

(TYPICA~

4 PLACES)

25

~//

2~/'>

1

J/~

TfJ

_._

",...

...

/ ;b

:.:

/'

/"

..

'

",

..

""/""

13

19'2124//~

18

(TYPICAL 6 PLACES)

17

11

Figure 8

Exploded View· BTR-200

10-9-12

(TYPICAL

4 PLACES)

(SEE DETAIL A)

3

34

(TYPICAL

8 PLACES)

8

26

DETAILC

Mechanical

Item No.

I 878519

2 54460001
3 878520
4 51847011
5
6 52264005 Connector Housing, 5 Pin I
7
8 970011-1
9

10

II

12
13
14
15
16
17
18

Part

No.

878560 Wireset

0086300 Copper strip, .343 x .005

50049003 Lockwasher
51845038 Screw, #4-40 x
51847003
450520 Standoff
51856001
270229
57722000
450464-1 Sprocket
450463-1
53431002

Description

PCB, Display
Receptacle, crimp
PCB, Audio
Screw, #4-40 x 1/4", flathead

Fish Paper 1

114",

Screw, #2-56 x 1/8" flathead

Screw, plastite, #2-28
Lug 2
Connector, antenna

Volume Control Knob
Switch Button, rectangular

pan head

Qty

AIR

16
18

7

Parts

Item No.

I

5

I

8

I

1
8
7

2

I

1
6

19

20&

22 878517 Connector bracket
23
24 150624-3 Telex label
25
26
27
28
29
30
31
32 878431 Covel'
33 (Not Used)
34 51845074 Screw, #6-32 x 1/4", pan head 8
35 557000 Nut, #6-32, hex
36
37

Part

No. Descrilltion

53431005 Switch Button, round 2

21

59908001 Connector, B4MB Switchcraft I

878439-3
878430
878521 Transmit Board 1
51845091
878662
51845093
51845055

500322

760386

(Not Used)

Front Panel
Chassis 1

Screw, #6-32 x 3/16"
Receive Board
Screw, #6-32 x 3/8" 6
#4-40 x 3/16", pan head

Screw, #6-32 x 3/8",
Insulator, Pre-impreg.

hex

head

Qty

I

1

I

10

1

7

I

I
I
I

2-4

CHAPTER 3

TRANSMIT, RECEIVE & AUDIO CIRCUIT,BOARDS

BTR-200 INSTRUMENT

DISASSEMBLY

1.

Remove 6 each #6 pan head phillips and 7 each
#14 head phillips screws and remove cover.
Refer

to

Figure

2.

Unsoldercoaxcablesfrom transmitandreceive
boards.

3. Unsolder3 copperstraps from receive board (if
present)

4.

Remove transmit and receive boards. Early
versions are equipped with snap-on nylon stan­doffs and later versions are held with #4 pan
head phillips screws.

8.

9.

Unplug the cable harness at
ribbon cables at P102 and P103.

10.

Remove 10 each #6 pan head phillips screws
holding the circuit board

11.

Slide the circuit board forward and lift up and
outfrom the rear.

12. Remove 8 each #6 pan head phillips screws
holding front panel

13. Remove 2 each #4 pan head phillips screws
holding headset connector bracket to chassis
and remove front panel.

to

chassis.

P1l4

to

the chassis.

and the two

o

5.

Remove ring nutsfrom the two RFconnectors.

6. Remove the hex head nylon screw and nut
holding

7. Remove 8 each #4 flat head phillips screws

holding the fourXLRconnectorhousings
chassis. On some early versions, the upper
PEM nuts will be replaced with nuts and lock­washers.

8.

Using an
screwdriver, unlock the XLRhousings by turn­ing the locking screw counterclockwise. Then
remove the
the rear.

Q1

08

XLR

XLR

to the chassis.

tool

or

small

housings by pulling them to

flat

to

the

bladed

14. Remove
circuit board to front panel and remove circuit
board. NOTE: When refitting this circuit
board the volume control on the front panel
must be positioned so that the pins and slots
mate properly.

15. Reassembly is the reverse

7 each phillips sorews holding front

of

these procedures.

3-1

TRANSMIT BOARD

CIRCUIT DESCRIPTION

U50IC is an amplifier whose gain is controlled by

of

the level
As the level here increases, the gain is decreased
and this results in a 2:1 compression characteristic.

Pre-emphasis is added by U501B. R504, R505,

and C508 set this at 115uS. C531 rolls the response
off above
call signal (see Audio Board Circuit Description).
Q501 is a Colpitts oscillator with the collector
tuned
VVC502 are added in
allow frequency modulationofthe oscillator. The
oscillator is operated
resonant point
linearity at the expense

trip1er and Q503 is a straight through amplifier.
The catTier frequency is thus nine times the crystal.
C529, C530 and L503 function as a low pass filter

and matching network.

audio entering the rectifier at pin 16.

10KHztofurther attenuate the 20 KHz

to

the third harmonic. T501, VVC501 and

selies with the crystal

10KHz

of

the crystal. This improves

of

some stability. Q502 is a

below the series

to

ALIGNMENT PROCEDURE

EQUIPMENT

REQUIRED:

o RF POWER METER
o FREQUENCY COUNTER
o DC VOLTMETER

1.

Connect the RF power meter and frequency

to

counter
sure the Transmit switch
the the Cont position.

2.

Adjust T502, T503, T504, VC501, and VC502

for maximum power. Note:

severly outofalignment and no output can

obtained, it may be necessmy
T502and T503 for maximum DC voltage at the
emitter

mum

adjust VC501and VC502 for maximum power.

the Transmit Antenna jack. Make

on

the

reat·

panel is set

If

adjustments are

to

first adjust

of

Q502. Then adjust T504 for maxi-

DC

voltage at the emitterofQ503. Now

be

3. Adjust T501 for the

Y501 Marking Frequency

154T570

177T800
183T730

4.

Repeat Steps 2 and 3 as necessmy.

5. Deviation
alignment.

will

COlTeCt

be adjustedinthe audio board

frequency:

154.570

177.800

183.730

3-2

Voltage Tables - Transmit Board (878521)

o

DEVICE

U501

DEVICE E B C

Q50l
Q502
Q503

1====-r===r===r====jPI=N=N=U=rM=B=E"F'R==~===r==~==l1

18

20

19

5 2.5 2.5 2.5 2.5 1 2.5 2.5 2.5

1

2

1.88

0.78

1.21

17 16

53 4

PIN

NUMBER

2.44

0.66 9.7

0.26

10

9.5

15

6

14

13 12

2.5 0

87

11

2.5

9

10

Q501, Q502

E

.---

U501

Q503

C

B

---,

C

E

B

)

3-3

Transmit

Board

Figure 9

Component

Layout (Foil Side)

C501

o

~nc5°bc50~

",y

R501 -e::>- D

O

+

0

I

R502

-e::>- V a

USO

1

+~04

9'

f1

-f

1505

Y

-e:::>-

C5<t9,.-t @ Wc501 r

CS08

c:::>

R504 C507

U -e::>-

~'3

G

VRS01

Transmit

Q~

~

0

u:;

o

Y

~

')

~

101

0 0501 a C517

WC502

\J

R508

Board

C503 PS12

...

0+

l'lN

ylQ

n I

U

OC506 U502 CS11 C522

I()C512QQ

lQ

nS005&'

00

I0 I

Q

l'l

00C516

+ R517 OS03 0 N

::!

05'3-/\10

~~

I0 Iy

0,

C518?t

Y R510 0 R 5

SILK

Al

~

YSOl

~

Component

SCREEN

Figure 10

Layout

REV.S

l'l

R51

6 Y Y

a

~

I Q §

C~:00Al~

~~N(]

o~

Q~~

(Component Side)

u:;l'l(")ol'l~~

o::y~~ylO

~~

~Ol

~

C525 a

~~~6

l'l

RS20

0 0

~@C501

~O

~

.....

~

C529 U

L502

t"03

"

0

O~

OC5:m~

0

3-4

P512

(
(

G50J

1UF

I

R502

JoK

C506

loopf

T

20

13

12

10K

R521

10K

..

14

R501

30K

R504-

10K

C507

1UF

,

R503

4.7K

o

G509 +

4.7UF

VR501

5K

C510

4-.7UF

t-+-'-~\I\1~-'

C513

N

T

100pf

G511

10UF

R507

T

I

47K

..

+

1

R508

47K

WC501

MV21

I

08

T

10

8

G501

+

lOoU~

I T

15

..

C504-

1UF

I

+

C505

4-.7UF

L501

C527
J.3PF

VC502

C530

Q503~502

MPs9011

T

L.

T

I

T

3-5

T501

FREQUENCY

FREQUENCY

154.570

177.800

183.730

Schematic Diagram Transmit Board - Version 1

C516

MHZ

27PF 39PF 100PF

MHZ

22PF 30PF 75PF 12PF 27PF

MHZ

22PF

DEPENDENT

C519

30PF 75PF

Figure

C520

11

COMPONENTS

C523 C524 C529 C530

18PF 33PF 68PF 20PF

12PF 24PF 47PF 15PF

TABLE

47PF 15PF

T501

-000

-002

-002

P512

(
(

1

j'"

U502

78L05

C506

100P~

"'f

10

20

12

C501

100U1

R502

30K

3.9K

8

+

j"

15

..

C504

I

1UF

j'"

R501

30K

16--l +

C505

4.7UF

C507

1

UF"

+

R503

15K

C511i

10U~

j'"

I

C530

T

T501

FREQUENCY

154.570

177.800

183.730

MHZ
MHZ
MHZ

FREQUENCY

C516 C519
27PF
22PF
22PF

DE:PENDENT

39PF
30PF
30PF

C520

100PF

75PF
75PF

COMPONENTS

C523

18PF
12PF
12PF

C524
33PF
27PF
24PF

TABLE
C529

68PF

47PF
47PF

C5JO
20PF

15PF
15PF

T501

-000

-002

-002

C529

I

7'

Figure 12

Schematic Diagram Transmit Board - Version 2