Maintenance Manual

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MAINTENANCE MANUAL

RT-1601 RECEIVER-TRANSMITTER

815 Broadhollow Road 631-755-7000

Farmingdale, N.Y. 11735 FAX 631- 755-7200

SECTION 1 DESCRIPTION AND OPERATION

1. General

This section provides a general description of the circuit functions and operation of the RT-1601 Receiver-Transmitter.

Subsequent information includes operation, equipment part numbers, block diagram discussion, and theory of operation.

NOTE: General information for the RDR-1600 Weather Radar System, such as system leading particulars, system

operation, and a system operational check is contained in the Radar System Installation Manual, TM106601 Maintenance

information for the DA-1203A Radar Antenna is contained in PART 1 of the Weather vision System Antennas

Maintenance Manual, I.B. 21000A.

2. Operation

The receiver-transmitter (R-T) operates by emitting very short, intense pulses of microwave energy, which are

reflected within the range of the radar system. A portion of the radiated energy, reflected by an object having

reflective characteristics, is returned along the same general path to the aircraft where it is received and

converted into digital data that is representative of the target size. The digital data is then routed to the radar

indicator where it is processed to give a visual presentation of the target.

The receiver-transmitter is housed in a short ½ ATR form factor case. Overall dimensions can be found on the

receiver–transmitter outline drawing. The mounting tray for the R-T unit, which is designed for front loading,

provides positive positioning and holding of the unit to the aircraft. The mounting tray is mounted to the aircraft,

and the R-T unit can easily be removed and replaced for servicing. Depending upon installation requirements,

different models of the mounting tray are available.

For ease of maintenance, all circuits are contained on plug-in boards. These PC boards are interconnected by

way of a ribbon cable, which makes all connections between PC boards. An interconnect PC board replaces

the conventional wiring harness arrangement.

The RT-1601 uses a frequency trimmable magnetron for reliable interrogation of beacon transponders; input

frequency in an accurate 9375 +5 MHz.

The RT-1601 functions as short-range pulse radar for high resolution ground mapping (search) and a long range

pulse for conventional weather. The reflected signal is received by the system’s sector scanning antenna,

amplified and digitized by the R-T unit, and then routed to the radar indicator. All system power requirements

are routed via the R-T unit to the radar indicator and the antenna.

3. Equipment Part Numbers

Table 1 lists the TELEPHONICS part number for the RT-1601 Receiver-Transmitter. A brief description

of the unit is also provided. Table 2 lists the major assemblies in the RT-1601

Summary of content (6 pages)

PAGE 1
MAINTENANCE MANUAL RT-1601 RECEIVER-TRANSMITTER SECTION 1 DESCRIPTION AND OPERATION 1. General This section provides a general description of the circuit functions and operation of the RT-1601 Receiver-Transmitter. Subsequent information includes operation, equipment part numbers, block diagram discussion, and theory of operation.
PAGE 2
MAINTENANCE MANUAL RT-1601 RECEIVER-TRANSMITTER TELEPHONICS PART NUMBER 379-2011-001 TYPE DESCRIPTION RT-1601 Provides X-band output to sector-scanning antenna. Reflected signal is amplified by receiver, digitized, and routed to the radar indicator. The magnetron is frequency trimmable and is designed to operate at 9375 +5 MHz to permit reliable triggering of the beacon transponder.
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MAINTENANCE MANUAL RT-1601 RECEIVER-TRANSMITTER where selection of either the modulator short pulse (0.2 usec) or the modulator long pulse (2.35 usec) is selected. Pulse width selection is made depending on the operation mode selected on the radar indicator. Modulator long pulse is selected for modes using a 200-Hz trigger; modulator short pulse is selected for modes using an 1536 Hz trigger. With either modulator pulse, a negative-going, 330volt, 110-ampere pulse is applied to the pulse transformer.
PAGE 4
MAINTENANCE MANUAL RT-1601 RECEIVER-TRANSMITTER the first local oscillator. If the first local oscillator is not very nearly 26.3 MHz above the magnetron frequency when the magnetron fires, the 10.3-MHz second AFC I-f will be outside the discriminator capture range. In this case the stop-sweep, or reset, circuit will initiate integrator reset and AFC sweep. To ensure that the first local oscillator does not lock on the difference frequency 26.
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MAINTENANCE MANUAL RT-1601 RECEIVER-TRANSMITTER used. The R-T unit first local oscillator operates at 9401.3-MHz to convert the standard 9375-MHz signal to a 26.3-MHz intermediate frequency. The same first local oscillator converts the 9310-MHz transponder signal to 91.3 MHz. The 91.3-MHz signal is amplified by the preamplifier and the 91.3MHz I-f amplifier, detected, and then applied to the video-detector buffer. 5. Detailed Theory of Operation A. Power Supply (1) General (See figure 1.
PAGE 6
MAINTENANCE MANUAL RT-1601 RECEIVER-TRANSMITTER BEACON RECEIVER Transmitter To Antenna STC MAGNETRON 9375Mhz +/- 5Mhz Pulse LONG PULSE MODULATOR 91.3Mhz Log AMP Vid-Detec Gain Adj STC Pulse 91.3Mhz 10.3Mhz 10.3Mhz T-R Limitter Pre AMP SHORT PULSE MODULATOR Log AMP BW Control Mixer Log AMP Vid-Detec Test Pulse STC WX Receiver FTC Switch BCN en 36.6Mhz 9375Mhz AFC Sweep 26.3Mhz MIXER 36.6Mhz 2nd L.O 9401.3Mhz AFC Discriminator Data Comparator BW Control VCO 1st L.