User's Manual

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P25XXFF1

Power Amplifier User’s

Manual

1. General Information

Power Amplifier (PA) is a AB/C-class unit. It is intended for amplification of single carrier phase (frequency)

modulated (manipulated) narrowband signals.

VHF range is divided by 4 working subranges:

- 136 – 144 MHz (subrange

“DA”);

- 144 – 152 MHz (subrange

“DB”);

- 152 – 162 MHz (subrange

“EA”);

- 162 – 174 MHz (subrange

“EB”).

Subrange code is reflected in the place “FF” of PA coding: P25-XXFF1-C6-001.

Code “XX” shows the input power range:

Code: R1 R2 R5 1 2 5 10 20

Range, W: 0.1-0.2 0.2-0.5 0.5-1.0 1.0-2.0 2.0-5.0 5.0-10 10-20 20-50

In the normal operating mode the minimum output power is 250 W.

Input VSWR is not greater than 1.6:1.

PA meets all FCC requirements to harmonic and spurious levels.

The nominal power supply voltage is 13.8 VDC.

DC current consumption does not exceed 50 A in the normal operation at 13.8V.

Working ambient temperature range lies from -30ºC to +60ºC.

Input and output power levels are set up in the factory. Customer has an opportunity to reduce the output power,

adjusting the special trimmer resistor in the unit, or picking up the value of outer resistor, connected to PA control pin.

PA has automatic power control loop that provides the stability of output power during the normal operation and all

necessary changes of power in the case of load mismatch or unit overheating.

PA is intended for rack mounting in the standard 19” cabinet. The front panel is 10” high. The

deepth of unit does not exceed 5”.

Four LEDs on the front panel indicate the status of unit operation.

The hole in the side wall gives an access to the trimmer resistor, which allows reducing the output power against the

set value.

There are two N connectors on the back of chassis.

There is power filtering DC connector at the back of chassis with four # 6-32 screws: 2 for “+” pole and 2 for “-“ pole.

There are 3 filter feedthroughs on the back of chassis that bring out the alarm signal, as well signals for the outside

power control.

Two fans on the back side of unit perform the forced air cooling.

2. Installation Guide

2.1. Unit installation shall provide proper air access to the unit; no obstacle for air is allowed

closer than 3” from fans.

2.2. Copper wires # 10 AWG shall be use in DC power line. Wires shall be crimped to ring terminals. Two parallel

wires shall be use for the positive voltage and two parallel wires shall be used for the ground side.

Put terminal under PI-shape shunts on DC connector. Do not remove shunts!

3. Operation Guide

3.1. Power supply voltage shall be in the range 13.8 V + 0.8 V.

3.2. The input power within the working frequency range shall be within the listed above limits.

It is prohibited to apply any RF signal out of the working frequency range with a power, greater

than 10% of the minimum rated one.

3.3. Green LED “DC ON” is on, when DC voltage is applied to the unit.

Summary of content (5 pages)

PAGE 1
P25XXFF1 Power Amplifier User’s Manual 1. General Information Power Amplifier (PA) is a AB/C-class unit. It is intended for amplification of single carrier phase (frequency) modulated (manipulated) narrowband signals. VHF range is divided by 4 working subranges: - 136 – 144 MHz (subrange “DA”); 144 – 152 MHz (subrange “DB”); 152 – 162 MHz (subrange “EA”); 162 – 174 MHz (subrange “EB”). Subrange code is reflected in the place “FF” of PA coding: P25-XXFF1-C6-001.
PAGE 2
3.4. Red LED “LOW POWER” is on when the output power drops below 80% - 85% of set level. In the majority of cases, it warns about an internal problem. However, the output power may fail due to high load VSWR (in this case, the LOW POWER LED tells that the power decrease is stronger than is needed for VSWR protection). 3.5. Red LED “HIGH VSWR” is on when the load VSWR exceeds 2.4 – 3.0. The output power is reduced. 3.6. Red LED “HIGH TEMP” is on when the heatsink temperature is over +85˚C.
PAGE 3
Experts in science, engineering, medicine, health, and industry work with organizations to develop standards for safe exposure to RF energy. These standards provide recommended acceptable levels for personnel who may be exposed to RF energy. The RF exposure levels described therein include substantial margins of protection. When properly installed and used, Crescend power amplifier products meet all government-established RF exposure levels.
PAGE 4
In instances where the effective antenna gain (antenna gain – feedline loss) differs from the example above, the MPE radius must be calculated by the licensee. The table below presents the results of calculations of the MPE radius for a 50 Watt UHF transmitter having various effective antenna gain values. Effective Antenna Gain (dBi) 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 • Minimum Safe Distance (meters) 4.45 5.00 5.61 6.29 7.06 7.92 8.89 9.97 Minimum Safe Distance (feet) 14.6 16.4 18.4 20.6 23.2 26.0 29.2 32.
PAGE 5
Under Industry Canada regulations, this radio transmitter may only operate using an antenna of a type and maximum (or lesser) gain approved for the transmitter by Industry Canada. To reduce potential radio interference to other users, the antenna type and its gain should be so chosen that the equivalent isotropically radiated power (e.i.r.p.) is not more than that necessary for successful communication.