M51102-1

M51102-1 microwave module for radio altimeter equipment

The M51102-1 is a microwave transmitting module with electrical frequency tuning. It is designed to generate frequency-modulated microwave oscillations for airborne radio altimeter equipment. The module is not a complete radio altimeter and does not calculate altitude by itself. Its function is to generate the microwave signal used in the transmitting section of the radio altimeter system. In operation, this signal is later radiated through the antenna path and used by the system for true-height measurement above the surface.

Microwave signal generation in the M51102-1

The M51102-1 works as a microwave signal source in the transmitter chain. It generates SHF oscillations in the radio altimeter frequency area, with electrical frequency tuning controlled by an external tuning voltage. This tuning voltage is applied to the tuning diode, allowing the generated frequency to vary within the specified range. Such frequency modulation is needed for continuous-wave FM radio altimeters, where altitude measurement is based on the relationship between transmitted and reflected signals.

M51102-1 in the A-037 radio altimeter

The M51102-1 module is used in the A-037 radio altimeter system, including configurations with A-037-1 series transceiver units. In this system, the module belongs to the transmitter section and forms the microwave signal required for radio-height measurement. The complete radio altimeter then transmits the signal toward the surface, receives the reflected return and processes the result through the receiver and signal-processing circuits. The M51102-1 is therefore one element of the RF path, not a standalone measuring instrument.

Use of M51102-1 in PP-5M equipment

In addition to A-037 radio altimeter applications, the M51102-1 is also associated with the PP-5M receiver, where it operates as part of the microwave signal path of the equipment. In this role, the module supports the formation or conversion of SHF signals within the receiver-related circuitry, depending on the equipment configuration. For supply or repair, the exact installation should be confirmed by the applicable documentation, because the same module designation may be used in different radio-altimeter or receiver assemblies.

Construction of the M51102-1 module

Structurally, the M51102-1 is manufactured in a shielded metal housing. The module includes a microwave oscillator, electrical frequency tuning elements, modulation circuitry and output matching circuits. The shielded housing protects the microwave circuit from external interference and helps maintain stable operating parameters. Since the module works in the SHF range, connector condition, soldering quality, shielding integrity and correct electrical parameters are important for reliable operation.

Operation with M45110-1 receiver module

The M51102-1 transmitting module may work together with the M45110-1 receiving module in continuous-wave FM radio altimeter equipment such as A-037 or RV-5M, depending on configuration. Together, the transmitting and receiving microwave modules form the functional SHF path used for signal generation, radiation, reception and conversion in the 4.2–4.4 GHz range. If altitude indication becomes unstable or the radio altimeter loses signal, both transmitting and receiving parts of the microwave path should be checked.

Technical requirements and supply notes for M51102-1

Operation of the M51102-1 is allowed only according to the applicable technical specifications and operating instructions listed in the product passport. Reliability and service life parameters are defined by Technical Conditions BSh2.210.141TU. For procurement, the full designation M51102-1 should be used. Alternative designations such as M51102, M-51102-1, M51102-01 or M 51102-1 can help identify the item, but the final match should be made by part number, technical specification, condition and documentation.

Product Name: Microwave Transmitting Module
Part Number: M51102-1
Product Type: SHF microwave module with electrical frequency tuning
Function: Generation of frequency-modulated microwave oscillations
System Application: Airborne radio altimeter equipment
Main Application: A-037 radio altimeter, including A-037-1 series transceiver equipment
Additional Application: PP-5M receiver equipment
Related Receiving Module: M45110-1, depending on radio altimeter configuration
Frequency Electrical Tuning Range: 93 ±2 MHz
Average Frequency of Tuning Range: 4300 ±15 MHz
Tuning Diode Voltage: Up to 30 V
Pulse Duration at 50 Hz Modulation Frequency: 0.3 ms
Pulse Amplitude: Not less than 100 mV
Output Power: Not less than 0.08 W
Load VSWR: Not more than 1.5
Collector Voltage: 15 ±5% V
Emitter Voltage: −6 ±5% V
Power Consumption: Not more than 3.0 W
Collector Current: Not more than 90 mA
Emitter Current: Not more than 90 mA
Tuning Diode Current: Not more than 1.5 mA
Minimum Operating Life: 3000 hours
Construction: Shielded metal housing with microwave oscillator, tuning, modulation and output matching circuits
Technical Specification: BSh2.210.141TU
Condition: As applicable
Alternate Designations: M51102; M-51102-1; M51102-01; M 51102-1; M51102 1
Technical Documentation: Product passport and operating instructions

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