Telex SR-50, ST300, SR-400 User Manual

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Telex SR-50, ST300, SR-400 User Manual

Telex

Operating Instructions

ST300

Transmitter

SR-400

17 Channel Receiver

SR-50

Single Channel Receiver

INTRODUCTION

WHAT IS THE TELEX SOUND

ENHANCEMENT SYSTEM?

Transmitter: The transmitter generates and amplifies a RF (Radio Frequency) carrier signal, modulates this carrier with the microphone signal, and radiates the modulated RF carrier.

Receiver: The FM VHF receiver is tuned to the frequency of the transmitter. The receiver picks up the radiated RF signal from the transmitter through the antenna and converts the RF signal into audio voltages for use with an earphone, headphone, button receiver, neckloop, etc. The receiver frequency must be matched to the transmitter frequency.

WHAT FREQUENCY BAND DOES THE TELEX SYSTEM OPERATE IN?

The Telex Systems feature a synthesized transmitter and single channel or synthesized receivers operating in the VHF Band between 72-76 MHz. See Table 1 for standard frequencies available.

Each transmitter channel can be utilized by any number of receivers in any given area. Up to eight simultaneous systems can be used, and with proper placement of adjacent channels, up to ten systems can be used.

ANT. ANT.

 

 

RF CARRIER

 

 

 

SIGNAL

 

SOUND

TRANSMITTER

FM

EARPHONE

SOURCE

RECEIVER

 

 

Figure 1

Block Diagram of Typical Sound Enhancement System

-1-

OFTEN ASKED QUESTIONS

Question: Can more than one system be used simultaneously?

Answer: Yes but never on the same frequency. You will need to have different frequencies for every receiver/transmitter combination. All transmitters are factory set for specific frequencies.

Question: Is the system more sensitive in any one particular direction?

Answer: No, the transmitter’s antenna radiates equally in all directions, but the signal is attenuated by your body, walls or other surrounding objects. The receiving antenna is essentially sensitive in all directions as well.

Question: Can the receiver receive other transmissions when the transmitter is turned off?

Answer: Yes it can. Telex systems operate in the VHF Band between 72-76 MHz. However, it is not susceptible to radio wave skip, CB’ers or standard FM radio transmissions.

The frequency your system operates on is computer selected for least interference, but there is no such thing as a 100% clear channel all the time, anywhere in the U.S.A., forever!

If the system is going to be used in a permanent fixed location, it should operate interference free until such a time or date when someone else begins using the same frequency.

If the system is going to be moving among various locations, you may run into occasional frequency conflicts.

Whenever the system is in use, the transmitter should be left on to prevent the receiver from picking up outside interference.

AVAILABLE FREQUENCIES

 

CHANNEL

FREQ. in MHz

 

 

 

 

 

 

A

72.100

 

 

 

 

 

 

B

72.200

 

 

 

 

 

 

C

72.300

 

 

 

 

 

 

D

72.400

 

 

E

72.500

 

 

 

 

 

 

F

72.600

 

 

G

72.700

 

 

 

 

 

 

H

72.800

 

 

I

72.900

 

 

 

 

 

 

J

75.500

 

 

 

 

 

 

K

75.600

 

 

 

 

 

 

L

75.700

 

 

 

 

 

 

M

75.800

 

 

 

 

 

 

N

75.900

 

 

 

 

 

 

O

74.700

 

 

 

 

 

 

P

75.300

 

 

Q

75.400

 

 

 

 

 

Table 1

Frequencies Available

-2-

TECHNICAL INFORMATION

SR-50 RECEIVER

GENERAL DESCRIPTION SR-50

The Telex SR-50 Receiver is a component of a system which operates on 17 factory preset channels in the 72 to 76 MHz frequency band. The receivers are designed to be used with Telex ST-300 and PST-170 transmitters, but they can be used with other brands of transmitters in the 72 to 76 MHz band provided the frequencies match.

OPERATING FEATURES

Volume OFF/ON Control: The thumbwheel control serves as both an off/on switch and as a volume control.

HEADPHONE JACK

TelexR

A

CHANNEL

VOLUME OFF/ON CONTROL

BELT CLIP

The receiver is turned off when the control is in the extreme counterclockwise position, when viewed from the rear and the volume is loudest when the control is in the extreme clockwise position.

Headphone Jack: The receiver jack accepts a 0.140-inch (3.5 mm) diameter miniature phone plug. A variety of accessory units can be plugged into the jack for reception of the desired channels being transmitted.

Belt Clip: The belt clip supplied is detachable by spreading the wire apart at the tops and removing one side of the clip form the case and then the other.

BATTERY

ORIENTATION

BATTERY COMPARTMENT COVER

Figure 2

Operating Features SR-50

-3-

SPECIFICATIONS

 

SR-50 Single Channel Receiver

 

 

Temperature Range .....................................................................................................

 

0 to +50 degrees C

Supply Voltage ...............................................................................................

 

2-3 Volts, (2) AA Batteries

Battery Life ..............................................................................................................

 

20-30 Hrs - Alkaline

 

 

8-10 Hrs - Nicad

Sensitivity (12 dB SINAD @ 25 kHz deviation) ...................................

 

0.5µ V typical/1µ V maximum

Distortion ...............................................................................................................................

 

less than 2%

Frequency Response - 100 Hz-10 kHz .............................................................

 

Less than 3 dB Variation

Audio Output @ 10% Distortion

 

 

Battery Input

2.0V

3.0V

Voltage

 

 

8 ohm

15 mW

80 mW

32 ohm

10 mW

50 mW

Controls and Connections ................................................................................

 

Volume OFF/ON Switch,

 

 

Audio Output Jack

SR-400 SYNTHESIZED

RECEIVER

General Description SR-400

The Telex SR-400 Receiver is a component of a system which operates on seventeen user selectable channels in the 72 to 76 MHz frequency band. The receivers are designed to be used with the Telex ST-300 and PST-170 Transmitters.

Operating Features

Volume OFF/ON Control: This thumbwheel control serves as both an off/on switch and as a volume control. The receiver is turned off when the control is in the extreme counter-clockwise position, when viewed from the rear, and the volume is loudest when the control is in the extreme clockwise position.

NOTE: A headphone or other device must be plugged in the headphone jack in order to turn on the SR-400. This is to prevent draining the batteries if the switch is accidently left on.

Treble Control: A push button treble control is provided to enhance higher frequency audio when the button is engaged, indicated by .

Headphone Jack: The receiver jack accepts a 0.140-inch (3.5 mm) diameter miniature plug. A variety of accessory units can be plugged into this jack for listening.

Belt Clip: The belt clip supplied is detachable by spreading the wire apart at the tops and removing one side of the clip form the case and then the other.

-4-

SET

 

 

SWITCH

 

 

BUTTON

 

BELT CLIP

 

 

HEADPHONE JACK

TREBLE CONTROL

 

SET

 

Telex

 

SR-400

 

 

 

P/N:71166000

S/N:00001

 

FCC ID: B5DE405

E.D.R.

BATTERY COMPARTMENT

VOLUME OFF/ON CONTROL

Figure 3

 

Operating Features SR-400

 

SPECIFICATIONS

 

SR-400 17 Channel Synthesized Receiver

 

 

Temperature Range .....................................................................................................

 

0 to +50 degrees C

Supply Voltage ...............................................................................................

 

2-3 Volts, (2) AA Batteries

Battery Life ..............................................................................................................

 

16-20 Hrs - Alkaline

 

 

12-16 Hrs - Nickel Metal Hydride

 

 

8-10 Hrs - Nickel-cadmium

Frequency Response ....................................................................................................

 

100-10 kHz ±3 dB

Sensitivity (12 dB SINAD @ 74 MHz)...................................................................................

 

1µ V max.

Distortion ...............................................................................................................................

 

less than 2%

Audio Output @ 10% Distortion

8 ohm

32 ohm

Battery Input

Voltage

 

 

2.0 V

15 mW

10 mW

3.0 V

80 mW

50 mW

Controls and Connections.................................................................................

 

Volume OFF/ON Switch;

 

Treble Control Switch; Channel Selection Switch

 

 

Audio Output Jack

-5-

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