User's Manual

DANIELS

ELECTRONICS LTD.

25W AM Power Amplifier Instruction Manual IM71-AMP3A130-25 3-1

3 INSTALLATION AND SITE OPERATION

The AMP-3 RF power amplifier is approved for operation with the VT-3A130 exciter. A complete

M3 subrack shipped directly from the factory is normally set to the appropriate options and output

power calibration as requested by the customer. These units require no tuning.

For AMP-3 amplifiers shipped separately from the MT-3 racks, install as outlined:

1. Connect the output of the exciter to the input of the AMP-3 Amplifier with the cable

provided.

2. Connect the PTT control signal from subrack to the PTT input of the power amplifier if the

PTT activation mode is selected.

3. Connect the antenna system, key the transmitter and check the LED status indicators.

The LED indicators will only illuminate when the power amplifier is keyed and are defined as

follows:

A. RF Power - indicates that a preset RF power level is present at the power amplifier

output. The threshold level is internally adjustable for various RF output levels

over the 10-25 watt range (factory set at 10 W.)

B. High VSWR – Alarm indicating that the load impedance mismatch is high. The

threshold level is internally adjustable from 2:1 to infinite:1 (factory set at 3:1.)

C. Overload – (VSWR Overload Alarm) indicates that the RF load impedance

mismatch is extremely high. Under this condition, the DC supply voltage

(nominally +28.0 Vdc) to the PA is interrupted and the status is locked until the RF

signal from the exciter is removed. The factory threshold level is set when the load

terminal is open.

D. Over Temp - (Over Temperature Alarm) a thermostat control switch interrupts the

DC supply voltage to the PA when the RF transistor body temperature exceeds

175

˚F (80

˚C). Utilizing circuit hysterisis, the thermostat will reset at 167 ˚F

(75

˚C).

The fan is activated automatically when the RF transistor body temperature reaches approximately

+40

C. The fan's operating temperature range is -20

C to +60

C. It will not operate when the

ambient temperature is below -20