The Telex Models TR-200 and TR-200P Belt-pack Transceivers one receive channel.
The TR-200 is a portable unit which communicates
in
full duplex with either the BTR-200 base station
or a mirror image TR-200.
Push-to-Talk with Lock-to-TaLk feature switch for the TR-200 and Push-to-Transmit Transmit feature for the TR-200P.
DESCRIPTION
are
designed with one transmit and
with
Lock-to-
The TR-200
transmit mode with the audio, to a switch. As many as four TR-200 belt-packtransceivers can operate in a fully duplex network
with
one Telex Model BTR-200 or BTR-200
Base Station.
The TR-200P Transceiver operates in the Push-to-transmit mode (the transmit and talk function activated together). Any number of TR-200Ptransceivers can be used with one BTR-200 or BTR-200 Operate only one transmitter at a time. Attemptingto use two transmitters simultaneously on the samechannel
Transceiver operates
will
cause interference.
in
the continuous
talk,
activated by
in
a half-duplex network
11
Base Station.
II
are
Page 5
SPECIFICATIONS
Power Requirements
Current Drain Temperature Range Dimensions
Weight Transmit Antenna Receive Antenna
RF RF
RF
Modulation
Modulation Limter Modulation Frequency Range Microphone Audio Input Microphone Input Sensluvlty Radiated Harmonics and Spurious Emissions
From the headset connector the microphone signal is first amplified by Q3 and Q4. This pair has a gain of 12 dB. Depending upon which type of
is
microphone is used, S1 or electret. The electret position provides an lldB
drop in gain to compensate for the extra output. is the user adjusted microphone gain control. UlD, Q1 and Q2 form responds to negative peaks exceeding about,.84 volt in amplitude. When such peaks are en- countered, Q2 conducts and charges C12, driving
Q1 toward pinchoff. This reduces the gain momen- tarily until the input signal is reduced. Visual in- dication of peak limiting is provided by LED 102 which is driven by U103 when the voltage at pin 3 exceeds the 1.3 volt reference. U103 is also used to sense the end of battery life and lights LED 102 continuously when this occurs.
D 1 (version 2 and later) isolates the time constant of the amplifier from that of the LED driver. The latter is much shorter than the former, and causes the LED to extinguish immediately upon removing the input signal.
!it for severalsconds.
U1C is an amplifier whose gain is controlled by the level of audio entering the rectifier at pin 16. level here increases, the gain is decreased and this results in emphasis is added by UlB. R23, R24, and C16 set this at 115 pS. Q5 is used to
anmd offand isdrivenby theqsh-to-talk latch
circuit. When SlOl driven on on the microphone audio. Releasing S 101 turns off the microphone. U104 does not change state under these conditions because C151 is discharged when the clock is pulsed. twice in quick succession, C151 will be charged for the second clock pulse and this will set the microphone is latched on via Dl04 and will
,
remain on until SlOl is depressed once again, resetting U 104.
a
viaD103. This lights LED 101 and gates
a
"O_n version 1
2:
1 compression characteristic. Pre-
set by the userto dynamic
peak limiting amplifier which
the^^^
turn
is
pressed in and held, Q106 is
If,
however, SlOl
will remain
As
the microphone
is
depressed
U104. Now
R9
the
Q7 is a Colpitts oscillator with the collector tunedto the third harmonic. added in series with the crystal to allow frequencymodulation of the oscillator. The oscillator isoperated 10 the crystal. This improves linearity at the expense
of some stability. through amplifier. The carrier frequency is thusnine times the crystal. C43, C44 and L7 function
as
a low pass filter and matching network.
KHz
L11, VVCl and VVC2 are
below the series resonant point of
Q8 is a tripler and Q9
is
a straight
ALIGNMENT PROCEDURE
Equipment
Deviation Meter
RF
Frequency Counter Audio Generator DC Power Supply
1. Solder one end of a 50 ohm coaxial cable from
the transmit antenna pad to ground. Connect the other end to the deviation meter, power meter, and frequency counter.
2. Connect the audio generator from pin 1 (hot) to pin 2 (ground) of the P.C. board connector. Set the output to 10
3. Set the power supply for 9 volts and connect it
from pin 11
connector.
4. Turn
5. Depress SlOl twice quickly to latch on the
6. Adjust L2, L3,
NOTE:
ment and no output can be obtained, it may be necessary to first adjust L2 and L3 for maximum
DC voltage at the emitter of for maximum DC voltage Now adjust C39 and C42 for maximum power.
R9
microphone. ground pin 8 of the P.C. board connector.
Dower.
If adjustmenu are severly out of align-
(+)
to maximum clockwise.
If
aligning with boards separated,
L4,
Required:
Power Meter
mV at 1
to pin 10
KHz.
(-)
of the P.C. board
C39 and C42 for maximum
Q8. Then adjust
at
the emitter of Q9.
LA
Page 12
7.
Adjust L11 for the correct frequency. This is
on
Y
1
printed
8.
Repeat steps 6 and
9.
Adjust
I228
and stamped into the rear case.
7
as
necessary.
for a deviation
off
3.
KHz.
VOLTAGE TABLES - TRANSMIT BOARD
Page 13
RECEIVE
BOARD
CIRCUIT DESCRIPTION
Signals from the receive antenna proceed through
3
tuned circuits, Q101, and 3 more tuned circuits to mixer Q103. Oscillator Q102 is a Colpitts with the collector tuned to the second harmonic. operates on the fifth overtone with C112 and L107 acting as mode suppressor. From the mixer the signal continues through FLlOl to second mixer
U~OIA.
KHz.
limited and detected by UlOlB. UlOlB contains a quadrature detector which is tuned by L109. UlOlC functions as a 16 operating the squelch. With no signal a large amount of noise is present at UlOl pin 11 and this is rectified by D101, lowering the voltage at pin 12 to less than .65 volt. This switches pin 14 to ground and mutes the audio. When a signal noise at UlOl pin 11 drops and causes the voltage at pin 12 to rise above .65 volt, releasing the clamp on the audio. R122 adiusts the bias current through
,
R121, R120, and ~i01 and is used to set tie squelch point. De-emphasis is provided by R117,
R125, and C128. U1A is an amplifier whose gain is controlled bq' the level of audio entering-the rectifier at pin 4. As the level here increases, the gain is increased and this results in a characteristic, which reverses the processing done in the transmitter. R159 is the user volume control and U105 drives the headset.
This downconverts the 10.7
After passing through FL102, the signal is
KHz
MHz
bandpass filter for
is
received, the
2:
1 expansion
ALIGNMENT PROCEDURE
E
uipment Required:
b
Signal Generator Audio Voltmeter SINAD Meter DC Power Supply
1. Solder one end of a 50 ohm coaxial cable from
the receive antenna pad to ground. Connect the other end to the signal generator.
Y
101
to 455
2. Connect the audio voltmeter and SINAD meter from pin 3 or 4 of the P.C. board connector to ground. Turn the volume control (R159) to its halfway point. separated, make the audio hookup from pin 6 to ground.
3.
Set the power supply for 9 volts and connect it from pin 11 connector.
4. Set the generator deviation to+3 Set the output level to 1 mV.
5.
Set the generator frequency to the receive fre-
quency. This is printed on
into the rear case.
.
6.
AdjustL109
7-
Adjust T101, L108, L109, L105, L104, L103, VC102 and VClOl in turn for best SINAD.
8.
set the generator output
9. Adjust R122 until the audio is squelched off.
10. Reduce the power supply voltage to
11. Adjust R135 until LED 102 just comes on.
NOTE:
(+)
to pin 10
for
maximum
K
aligning with boards
(-)
of the P.C. board
KHz
at 1
Y
101 and stamped
audio.
to
1
u~.
7
volts.
OPTIONS-CIRCUIT DESCRIPTION
may
~t
only the audio on and off with the push-to-talk button but also the transmitter itself. This would be the case transmitting on the same frequency were being used removed and
For the TR-200 units which do not communicate with with a mirror image TR-200, sidetone must be added. Unlike the base station the TR-200 does not retransmit the received signal. For C51 and R46 are installed.