Section 1. GENERAL INFORMATION

TM 11-5820-918-13

SECTION 1

GENERAL

INFORMATION

INTRODUCTION

1-2. This manual provides operating and service instructions for the TCS-4B trans-

mitter. The information is presented in seven sections. Section 1 provides a brief

description of the equipment and operating specifications. Unpacking instructions,

site requirements, cabling data and installation instructions are included in Section

2. Section 3 provides information on operator controls and indicators and describes

operating procedures. In Section 4 are functional descriptions of transmitter circuits.

Section 5 describes preventive and corrective maintenance procedures for the trans-

mitter and gives a performance verification checkout. Section 6 contains the wire

lists for reference during maintenance. All oversize drawings, such as schematics,

are grouped in the back of this manual as a foldout (FO) section.

1-3. GENERAL DESCRIPTION

1-4. The TCS-4B transmitter (figure 1-1) is one part of an HF Radio Sounder Set

used for frequency management of HF circuits. It is used at one end of an HF radio

circuit and transmits a CW signal which is swept in an upward linear ramp between

2-16 or 2-30 MHz in 4 minutes and 40 seconds. The RCS-4B radio receiver is a com-

panion unit to the TCS-4B transmitter and is located at the other end of the circuit.

When properly synchronized with a TCS-4B , the RCS-4B receives all radio energy

emitted by the transmitter that ionospheric propagation permits. One RCS-4B can

be synchronized with up to three TCS-4B transmitters.

1-5. A third part of the set is the Model RSS-4 Spectrum Monitor. The RSS-4 per-

mits a frequency manager to know the occupancy of all 6 kHz channels in the 2-30

MHz band for the last 30 minutes. Thus, the TCS-4B/RCS-4B sounder system tells

the frequency manager what band of frequencies will propagate over a given path,

and the RSS-4 indicates which channels within the propagating band are free from

1-6. The TCS-4B has up to 100 watts RF output power for transmission directly

by a broadband antenna (required but not supplied). The TCS-4B signal can also

be diplexed onto the same antenna employed for the user's communication transmitter

(up to 2.5 kW PEP) using the diplexer assembly that is part of the TCS-4B . In the

diplexed mode, only 2 percent of the TCS-4B power (2 watts) is coupled onto the

user's antenna; the remaining power (along with about 2 percent of the communi-

cations transmitter power) goes to an internal dummy load. If the communications

transmitter is used on the same circuit being sounded by the TCS-4B, then the prop-

agation data obtained in the sounding accounts for all radiation characteristics of

the user's antenna.

1-7. The TCS-4B transmitter may be programmed to blank transmissions in up to

sixteen bands, up to 60 kHz wide. The center blanking frequency of each band is

programmed via front panel thumbwheel switches. Frequency blanking is usually

not an important consideration when operating in a diplexed configuration because

of the low radiated power. However, it is a useful feature to reduce potential inter-

ference effects on communications receivers co-located with the TCS-4B transmitter.