Telex Radiocom BTR-200 Series Service Manual
-----------------------~--~--_._
_-
_.
-
ca
::J
c:
ca
><
.:2
W~
....I
-s;:
Wi..
....
~
Ci
c)
mm",,~~
:E
w
..J I-en
<t
enW
Z
>-
enD:
Q(/):Em
l~iDD
~
fa
80
a~~~
~
d
a:
~
lll~L
...
lOO~
it
3=
~
ttl
.-"\
j
€l
X
W
.J
W
I-
()
Table
of
Contents
Page
Chapter
1
General Description
1-1
Specifications BTR-200
1-1
Controls and Connections 1-2
Front Panel 1-2
Rear Panel 1-5
Chapter
2 - IdentificationofCircuit
Board
Revision
and
Version
Audio Boards ......•.................................................................................................................................... 2-1
Receive Board 2-2
Transmit Board 2-3
Chapter
3 - Transmit, Receive & Audio Circuit Boards
BTR-200 InstrumentDisassembly 3-1
Transmit Board 3-2
Circuit Descdption 3-2
Alignment Procedure
: 3-2
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
Receive Board (70714000) 3-10
Equipment Required 3-10
Receive Board (750309) 3-11
Equipment Required 3-11
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
,
::
3-27
Audio Board Circuit Description 3-27
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
Supply 3-28
Alignment Procedure 3-29
Equipment Required 3-29
-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
List
of
Illustrations
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
Description Page
Headset XLR Connector Wiring 1-2
Front Panel-BTR200
1-3
Rear Panel - BTR-200 1-4
Location
of
Rev Level for Versions 1and 2 (Audio Board)
2-1
LocationofRev Level for Versions 3
thlU
6 (Audio Board)
2-1
LocationofRev Level for Versions I and 2 (Receive Board) 2-2
Location
of
Rev Level for Versions I and 2 (Transmit Board) 2-3
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
I and 2 (70714000) 3-17
Schematic Diagram Receive Board Version 2 (750309) 3-18
Receive Board Component Layout (Component Side) Version
1..
3-19
Receive Board Component Layout (Foil Side) 3-19
Receive Board Component Layout (Component Side) Version 2 (750309) 3-19
Schematic Diagram Receive Board Version
I (750309) 3-20
Block Diagram Versions 1 and 2 3-31
Block Diagram Versions 3
thlU
6 : 3-32
Audio Board Component Layout (Component Side) Versions land 2 3-33
Audio Board Component Layout (Foil Sde) 3-34
Schematic Diagram Audio Board Version
I 3-35
Schematic Diagram Audio Board Version 2 3-36
Details
of
Board Differences Between Versions I and 2 3-37
Details
of
Board DifferenceinVersions 3, 4,5,and 6 3-38
Audio Board Component Layout (Component Side) Version 6
with Detailed Areas Showing Differences ofVersions
3,4,5,
and 6 3-39
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
-11-
CHAPTER 1
: -
')
GENERAL
DESCRIPTION
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
to
other
equipment
such
as a
hardwired intercom system.
n
1-1
CONTROLS
and
CONNECTIONS
FRONT
PANEL (Refer to Figure 2)
Power
ON/OFF
Switch: Push this switch once
to
turn power ON; push it againtoturn the power
OFF.
Power
ON
Indicator:
The Power ON Indicator is
illuminated when the Power
ON/OFF Switch is
pushed in the
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
1.
MICROPHONE
GROUND
BALANCED
AUDIO
OUT
MICROPHONE
AUDIO
Figure 1
Headset
XLR
ConnectorWiring
1-2
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
to
control the input level ofthe
local headset mic. This input is protected
from
overloads by means of a gain compressor whose
operation
is
signaled by the gain LED indicator.
Portable
EnableSwitches
and
Indicators: When
in the
"IN"
position, the Enable switches allow the
user of the conesponding portable unit
to
be heard
by others connected
to
the system. Wheninthe
"OUT" position, the respective portable will
be
muted, but this portable will still be abletohear
all
other selected remotes and interfaces. The indicators normally show the presence
of
a portable
transceiver in use
on
the channel corresponding
to
that indicator.
INTERCOM INDICATOR
27160-8-00I-A
LOCAL MIC
OVE
RMODULATION
INDICATOR
LOCAL MIC GAIN CONTROL
LOCAL
PUSH-TO-TALK
INDICATOR
MIC
ON
PUSIH-lO-TALKI
LOCK-TO-TALK SWITCH
PORTABLE CARRIER INDICATORS
I
I
I
~OCAL
HEADSET VOLUME
I
i
AUXILIARY
ENABLE
INDICATOR
ENABLE SWITCHES
TO
RECEIVE
PORTABLE
TRANSMITTERS
I.-.--~
Portabte
Station
Connect--
AUXILIARY
LEVEL
CONTROL
AUXILIARY
ENABLE
SWITCH
INTERCOM LEVEL CONTROL
INTERCOM
ENABLE
SWITCH
POWER
ON
INDICATOR
Headset
8TR-200
1I
. LOCAL HEADSET CONNECTOR
Figure 2
Front
Panel-BTR200
1-3
27160-B-002-A
AUXILI
ARY
OUTPUT
CONNECTOR
RECEIVE ANTENNA CONNECTOR
A~'~
300
rnA
-------
POWER JACK
o
Power
SPEAKER GAIN CONTROL
TELEX
COMMUNICA
TtONS.
INC.
Fex
1.0.
850BTR-200
MADEINU.S.A.
Jack
CO
G~
LSpeaker-l
INTERCOM CONNECTORS
o
Intercom
Input
Transmit
1
TRANSMITTER
SWITCH
Headset
Mic
r"=-h
r~l
Oyn
fit
Cant
Off
Remote
HEADSET MIC
SELECT
SWITCH
AUXILJARY INPUT CONNECTOR
o
TRANSMITANTENNA
CONNECTOR
Transmit
Anteflna
SPEAKER/LOCAL
MONITOR
(8nMIN.)
Figure 3
Rear
Panel BTR-200
1-4
Ext
Intercom Switch, Level Control,
and
In-
dicator: This switch enables the wired intercom
interface when "IN", and disables it when "OUT".
For
RTS
intercoms, the "IN" position is channel A
and the "OUT" position ischannelB. Ascrewdriver
adjustable control is provided to control the input
level
of
the wired intercom.
Auxiliary Audio
Enable
Switch, Level Control,
and
Indicator:
Theswitchenablesand disables the
Auxiliary intelface when "IN" and "OUT", respectively. The functionofthe level control here is the
same as that described for the intercom.
REAR
PANEL (Refer to Figure 3)
(j
Transmit
Antenna
Connector: Connect5/8-wave
antenna(supplied)
to
this connector. Antenna color
should match connector dot
on
BTR-200.
Receive
Antenna
Connector: Connect 5/S-wave
antenna (supplied)
to
this connector. Antennacolor
should match connector dot
on
BTR-200.
Transmit
Switch: Slide switch that allows the
operator
to
select oneofthree transmit modes.
In
the "OFF" position, the transmitter is always off.
This mode may be used
if
the base is functioning
solely
as
a monitor. In the "CONT" position, the
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
an
Electret
or
Dynamic microphone. This switchi~factory preset
to
DYN Position.
NOTE: All Telex headsets that are used with this
intercom are dynamic type microphones.
Intercom
Connectors: Connections to interface
the BTR-200 with a wired intercom system.
Auxiliary
Output/Input
Connectors:
Can
be
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
Jack:
Forexternal AC wall supply adaptor
(supplied) or any filtered 12 to 14
VDC/300 rnA
source, or 13.0
VAC
RMS/300 rnA source.
Speaker
Jack:
Allows the user to connect an ex-
ternal speaker
(8
ohms minimum)tothe unit.
Speaker
Gain
Control: Screwdriver adjustable.
Adjust the gain control clockwise to increase
speaker gain
or
counterclockwise
to
decrease
speaker gain.
NOTE: Leave setting counterclockwise
if
no
speaker is attached.
1-511-6
Blank
CHAPTER 2
IDENTIFICATION
OF
CIRCUIT BOARD
REVISION AND VERSION
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 BOARDS
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.
AUDIO BOARD
RECEIVE BOARD
LOCATION
OF
SWITCHBOARD
70723-000 REV A COMP
"'-.
••• _
r--------.
:I.
•
.2"!!2";!!.'!!!.I!.E!..~~_:
....
__
..
~---~_.:
o
Figure 4
Location
of
Rev Level for Versions 1
and
2
REV LEVEL LOCATED
.--
UNDER TRANSMIT
BOARD
70723-000 REV C
AUDIO BOARD
c . .
a:
I U I
«
I
if
0
I 0 I
I 3 I
!Xl
I & I
l-
'"
I
:E
L_
en
z
«
a:
I-
U
I
I
Figure 5
LocationofRev Level for Versions 3
thru
6
2-1
Rev C boards can be either Verion 3 or 4. The
differences are all parts values:
Rev D boards are all version 5.
Rev
E boards are all version
6.
Rev B was not produced.
750309 COMP REV A
Version
RIOI
RI03
Rl25
Rl30
Rl31
Rl32
Rl33
Rl54
Rl62 Rl68
Rl70
Cl33
3
82K 82K
6.2K 1.5K
1.5K 1.5K
1.5K 5.6K
9.lK
68K
68K
lO~F
4
200K
200K
4.7K
4.7K
4.7K 4.7K 4.7 8.2K 3.9K 15K 10K
22~F
RECEIVE
BOARD
The
BTR-200
uses oneoftwo receive boards.
Figure
6
LocationofRev Level
for
Versions 1
and
2
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 weremanufacturing changes that did not change the schematic.
750309 Rev
Aboards are version
1.
750309 Rev
Band
C boards are version
2.
Some early version 1 boards did not have a shield
over the oscillator section
..
70714000
R327
R345 R363
R381 VR302
VR304 VR306 VR308
Version
1
4.7K 4.7K 4.7K 4.7K 10K 10K 10K 10K
2
10K 10K 10K 10K 20K 20K 20K
20K
2-2
TRANSMIT BOARD
,.--
--------
I '70"12'
....
-000
rEVAOONP
I
70724-000 REV A COMP
7--------
o
Figure 7
LocationofRev Level for Versions 1
and
2
All
Rev
Aboards
are
version1.Rev B boards
may
be
version 1 or
2:
Version R503 R521
CS31
1 4.7K 10K
.0033uF
2 15K
68K .001 uF
2-3
DETAILB
7
Item No.
Part
No. Descrilltion
Qty
19
53431005 Switch Button, round 2
20&
21
(Not Used)
22 878517 Connector bracket
I
23
59908001 Connector, B4MB Switchcraft I
24 150624-3 Telex label
1
25
878439-3
Front Panel
I
26
878430
Chassis 1
27
878521 Transmit Board 1
28
51845091
Screw, #6-32 x 3/16"
10
29
878662
Receive Board
1
30
51845093
Screw, #6-32 x 3/8" 6
31
51845055
#4-40 x 3/16", pan head
7
32 878431 Covel'
I
33 (Not Used)
34 51845074 Screw, #6-32 x 1/4", pan head 8
35 557000 Nut, #6-32, hex
I
36
500322
Screw, #6-32 x 3/8",
hex
head
I
37
760386
Insulator, Pre-impreg.
I
Mechanical
Parts
DETAILC
8
26
Item No.
Part
No.
Description
Qty
I 878519
PCB, Display
I
2 54460001
Receptacle, crimp
5
3 878520
PCB, Audio
I
4 51847011
Screw, #4-40 x 1/4", flathead
8
5
878560 Wireset
I
6 52264005 Connector Housing, 5 Pin I
7
0086300 Copper strip, .343 x .005
AIR
8 970011-1
Fish Paper 1
9
50049003 Lockwasher
16
10
51845038 Screw, #4-40 x
114",
pan head
18
II
51847003
Screw, #2-56 x 1/8" flathead
1
12
450520 Standoff
8
13
51856001
Screw, plastite, #2-28
7
14
270229
Lug 2
15
57722000
Connector, antenna
2
16
450464-1 Sprocket
I
17
450463-1
Volume Control Knob
1
18
53431002
Switch Button, rectangular
6
32
3
10-9-12
(TYPICAL
4 PLACES)
(SEE DETAIL A)
34
(TYPICAL
8 PLACES)
31
/(TYPICAL
3 PLACES)
,fj
13
11
Figure 8
Exploded View· BTR-200
10-9-12~
(TYPICAL
4 PLACES)
31
(TYPICAL
4 PLACES)
17
30
(TYPICAL\~e.
BOTH SIDES)
":
~.
th
13
10
--===--
(TYPICA~
4 PLACES)
_._
:.:
/'
1
",...
...
/"
..
'
/ ;b
",
J/~
..
""/""
10
"*--/t-'12
DETAIL A
25
~//
TfJ
2~/'>
19'2124//~
18
(TYPICAL 6 PLACES)
2-4
CHAPTER 3
TRANSMIT, RECEIVE & AUDIO CIRCUIT,BOARDS
BTR-200 INSTRUMENT
DISASSEMBLY
o
1.
Remove 6 each #6 pan head phillips and 7 each
#14 head phillips screws and remove cover.
Refer
to
Figure
8.
2.
Unsoldercoaxcablesfrom transmitandreceive
boards.
3. Unsolder 3 copperstrapsfrom 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.
5.
Remove ring nutsfrom the two RF connectors.
6. Remove the hex head nylon screw and nut
holding
Q1
08
to the chassis.
7. Remove 8 each #4 flat head phillips screws
holding the fourXLRconnectorhousings
to
the
chassis. On some early versions, the upper
PEM nuts will be replaced with nuts and lock-
washers.
8.
Using an
XLR
tool
or
small
flat
bladed
screwdriver, unlock the XLR housings by turn-
ing the locking screw counterclockwise. Then
remove the
XLR
housings by pulling them to
the rear.
3-1
9.
Unplug the cable harness at
P1l4
and the two
ribbon cables at P102 and P103.
10.
Remove 10 each #6 pan head phillips screws
holding the circuit board
to
the chassis.
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
to
chassis.
13. Remove 2 each #4 pan head phillips screws
holding headset connector bracket to chassis
and remove front panel.
14. Remove
7 each phillips sorews holding front
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
of
these procedures.
CIRCUIT DESCRIPTION
TRANSMIT BOARD
ALIGNMENT PROCEDURE
U50IC is an amplifier whose gain is controlled by
the level
of
audio entering the rectifier at pin 16.
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 rollsthe response
off above
10KHztofurther attenuate the 20 KHz
call signal (see Audio Board Circuit Description).
Q501 is a Colpitts oscillator with the collector
tuned
to
the third harmonic. T501, VVC501 and
VVC502 are added in
selies with the crystal
to
allow frequency modulationofthe oscillator. The
oscillator is operated
10KHz
below the series
resonant point
of
the crystal. This improves
linearity at the expense
of
some stability. Q502 is a
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.
3-2
EQUIPMENT
REQUIRED:
o RF POWER METER
o FREQUENCY COUNTER
o DC VOLTMETER
1.
Connect the RF power meter and frequency
counter
to
the Transmit Antenna jack. Make
sure the Transmitswitch
on
the
reat·
panel is set
the the Cont position.
2.
Adjust T502, T503, T504, VC501, and VC502
for maximum power. Note:
If
adjustments are
severly outofalignment and no output can
be
obtained, it may be necessmytofirst adjust
T502and T503 for maximum DC voltage at the
emitter
of
Q502. Then adjust T504 for maxi-
mum
DC
voltage at the emitterofQ503. Now
adjust VC501and VC502 for maximum power.
3. Adjust T501 for the
COlTeCt
frequency:
Y501 Marking Frequency
154T570
154.570
177T800
177.800
183T730
183.730
4.
Repeat Steps 2 and 3 as necessmy.
5. Deviation
will
be adjustedinthe audio board
alignment.
Voltage Tables - Transmit Board (878521)
U501
11
20
19
DEVICE
1====-r===r===r====jPI=N=N=U=rM=B=E"F'R==~===r==~==l1
.---
---,
18
17 16
15
14
13 12
5 2.5 2.5 2.5 2.5 1 2.5 2.5 2.5
2.5
2.5 0
9
10
87
6
53 4
2
1
U501
PIN
NUMBER
o
DEVICE E B C
Q50l
1.88
2.44
10
Q502
0.78
0.66 9.7
Q503
1.21
0.26
9.5
Q501, Q502
C
B
E
Q503
C
E
B
)
3-3
Figure 9
Transmit
Board
Component
Layout (Foil Side)
C503 PS12
C501
0
+
...
0+
n I
l'l
C525 a
l'l
RS20
I
USO
1
~
l'lN
U
R51
6 Y Y
o
')
ylQ
OC506 U502 CS11 C522
~~~6
0 0
R502
+~04
I()C512QQ
a
~
~@C501
-e::>- V a
lQ
+ R517 OS03 0 N
~nc5°bc50~
9'
~
nS005&'
::!
05'3-/\10
I Q §
t"03
",y
f1
-f
1505
CS08
~'3
101
00
I0 I
~~
I0 Iy
C~:
00
Al~
~O
"
O~
Y
-e:::>-
c:::>
Q~
Q
0,
~~N(]
u:;l'l(")ol'l~~
~
0
OC5:m~
R501 -e::>- D
~
0 0501 a C517
o~
o::y~~ylO
.....
~
C529 U
R504 C507
u:;
0
Y
WC502
l'l
00C516
C518?t
Q~~
~~
~Ol
L502
O
G
o
\J
Y R510 0 R 5
~
0
C5<t9,.-t @ Wc501 r
SILK
SCREEN
REV.S
U -e::>-
Al
R508
~
YSOl
VRS01
~
Figure 10
Transmit
Board
Component
Layout
(Component Side)
3-4
R502
R501
JoK
30K
C506
loopf
T
G50J
20
12
,
R503
R521
R504-
C507
P512
1UF
10K
10K
1UF
4.7K
10K
(
I
..
13
14
(
1
10
I
+
C505
T
8
15
4-.7UF
G501
+
..
C504-
lOoU~
I
1UF
I T
C530
o
G511
I
+
10UF
..
G509 +
R508
N
47K
4.7UF
C510
4-.7UF
WC501
VR501
t-+-'-~\I\1~-'
MV21
08
T
5K
C513
R507
T
100pf
47K
T
T501
3-5
FREQUENCY
DEPENDENT
COMPONENTS
TABLE
FREQUENCY
C516
C519
C520
C523 C524 C529 C530
T501
154.570
MHZ
27PF 39PF 100PF
18PF 33PF 68PF 20PF
-000
177.800
MHZ
22PF 30PF 75PF 12PF 27PF
47PF 15PF
-002
183.730
MHZ
22PF
30PF 75PF
12PF 24PF 47PF 15PF
-002
Figure
11
Schematic Diagram Transmit Board - Version 1
L501
C527
J.3PF
VC502
Q503~502
MPs9011
L.
T
I
T
15
P512
(
(
1
j'"
C506
100P~
"'f
20
12
10
8
C501
+
100U1
j"
R502
R501
30K
30K
3.9K
16--l +
C505
4.7UF
..
C504
I
1UF
j'"
C507
1
UF"
+
R503
15K
C511i
10U~
j'"
U502
78L05
T501
FREQUENCY
DE:PENDENT
COMPONENTS
TABLE
FREQUENCY
C516 C519
C520
C523
C524
C529
C5JO
T501
154.570
MHZ
27PF
39PF
100PF
18PF
33PF
68PF
20PF
-000
177.800
MHZ
22PF
30PF
75PF
12PF
27PF
47PF
15PF
-002
183.730
MHZ
22PF
30PF
75PF
12PF
24PF
47PF
15PF
-002
Figure 12
Schematic Diagram TransmitBoard - Version 2
C530
I
C529
I
7'
T
Loading...