Crescend P2-RTK-450 User Manual

Crescend P2-RTK-450

Power Amplifier User Manual

1. General Information

The P2-RTK-450 is a AB class power amplifier (PA), intended to work with UHF RTK positioning syst ems,
amplifying phase modulated signals.

PA has the automatic gain control (AGC) l oop. The gain value is set up in the factory.
PA is protected against the load mismatch and ov erheating. It is also protected against exces sive DC power

supply voltage and DC voltage reversed polarity (for short time). PA has a current limiter, which threshold goes
down in the case of overheating.

PA provides LED indication of normal and alarm modes, as well as the combined alarm signal.
PA contains an externally controlled by-pass line, activated either when the power supply voltage is removed, or

when the special pin “SH/D” is pulled to the ground.
There is a forced air cooling system, working when the unit is in the amplifying mode.
The general parameters of RTK-450 in the normal operation mode are listed below:

Frequency range of operation (f), MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450 - 470;

Input power (Pin), W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.4 – 2.0;

Input return loss, dB, not less than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10;

Gain in the normal operation (G), dB, nominal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11;

Bypass insertion loss, dB, not greater than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0;

DC power supply voltage (Vsup), V

- nominal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.8;

- working range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.0 – 17.0;

DC current (Io), A, not greater than

- in amplifying mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5;

- in quiescent mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8;

- in by-pass mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.002;

Working ambient temperature range, ºC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -30 to +60;

Threshold of overheat protection activation: heat sink temperature, ºC . . . . . .. + (85 + 5);

RF connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Ohm, N (F);

DC connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . screws # 6-32 AWG.

2. Construction
The unit is intended for installation in a standard 19” cabinet rack, where it takes 4U (7.0”) in the vertical

direction. Its depth does not exceed 5”.
There are four LED at the front panel that indicat e the status of unit operation.
There are two N connectors, DC block, four pins (f i l ters) and two ground poles at the rear of chassis. A l so, the fan

is placed over the heatsink at the rear.

2

3. Installation
Unit installation shall provide proper air access to the unit; no obstacle for air is allowed closer than 3” from fan.

Unit shall be protected against the direct solar li ght and precipitation. The air inlets and outlet s sh oul d be checked
every 30 days and cleaned if necessary. If the equipment is operated in a severe dust environment, i t should be
checked and cleaned more often. If dust and dirt are allowed to accumulate, the cooling efficiency will be
diminished. Using either compressed air or a brush with soft bristles, loosen and remove accu m ul ated dust and
dirt from the air inlet panels.

Check that the fans are running smoothly. A slow ru nni ng or noisy fan may indicate an imminent fan f ai l ure. Heat
is one of the biggest factors in reducing the reliabi li ty of the amplifier. Ensure the fan has access to cool and
clean airflow within the rack.

Copper wires # 12 AWG shall be use in DC power lin e. Wires shall be crimped to ring terminals.
Pre-tinning of crimps is recommended.

Use # 18 or # 20 AWG wire for unit status monitori ng circuit. Connect this wire to the pin “AL A RM ”.
Use # 18 or # 20 AWG wire for forced switching to by-pass mode ci rcuit. Con nect this wire to the pin “SH/D”.
Make sure all connections are constructed and implemented properly with best practices.
Make sure that DC power supply voltage and RF sou rce f requency and power are in the

mentioned above limits and that the DC polarity is correct before applying DC power to the amplifier.

Notes: - The reversed DC polarity protection circuit may not operate longer than 0.3 sec;

- Input power shall not exceed 3 W in the working frequency rang e and shall not exceed

0.3 W out of the specified frequency range of operation.

4. Operation

Green LED “DC ON” is on and fan is running when DC power supply voltage i s appli ed to the unit, its value

does not exceed 17 V and pin “Sh/D” is not connect ed to the ground.
Red LED “LOW OUTPUT” is on if gain is less than 6 dB or input power is less than 0.1 W.
Red LED “HIGH VSWR” is on when the load VSWR ex ceeds 2:1.
Red LED “HIGH TEMP” is on when the heat sink temperature reache s +(85 + 5)ºC.

The voltage at filter “ALARM” is about 0.5 V less than power supply voltage during normal operation a nd
drops to 0.3V or less when any of mentioned above red LEDs turn on. If a 2 kOhm resistor is connected
between this filter and the ground, a TTL compati ble output is created.

When switching the PA to the by-pass mode, the resistance between pin “SH/D” and ground shall be less
than 100 Ohm, or, if a transistor key is used, the voltage drop on the key shall not exceed 0.2 V . The
current, coming out from pin “SH/D” does not exceed 1.7 mA.

5. FCC RF Exposure Requirements

CAUTION: This transmitter must be rest rict ed to work related operations in a Controlled RF exposure
environment. All qualified end-users of this dev i ce must have the knowledge to control their expos ure
conditions and/or duration, and the exposur e conditions and/or duration of their passengers a nd bystanders,
to comply with the General Population / Uncontrolled MPE limit and requirements.

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