User Manual

DE
DANIELS
ELECTRONICS
3-4 VHF Amplifier Instruction Manual VT-3 132 - 174 MHz
4
4. Monitor the +9.5 Vdc and 13.8 Vdc supply current and adjust R7, the output power
adjustment, so that approximately 1 Amp is being drawn on the +9.5 Vdc line and
1.3 Amps or less is being drawn on the 13.8 Vdc line. This should produce
approximately 8 Watts.
5. If only a 6 or 7 watt output is obtained, adjust the low pass filter coil pairs L2/L3 and
L1/L4 to obtain 8 watts.
3.6.2.2 Output Power Alarm (Forward Power)
Open Collector Output
* note: the output power alarm output is factory configured as an open collector output
so a pull-up resistor may be required on transmitter pin B26 if one is not already
present.
1. Adjust R7, the output power adjustment, to the output power at which the Output
Power Alarm is to be activated.
2. Monitor transmitter pin B26, the Output Power Alarm line, and slowly turn R21, the
output power alarm adjustment, clockwise until pin B26 goes low. The alarm is now
set for the current output power of the transmitter.
Linear Output
1. Open the amplifier case to disable (open circuit) jumper JU2 and enable (short)
jumper JU1.
2. Monitor transmitter pin B26 with a voltmeter.
3. Adjust R7, the output power adjustment, for full transmitter output power.
4. Adjust R21, the output power alarm adjustment, so that the voltmeter indicates +7.5
Vdc for full transmitter output power.
5. Turn R7, the output power adjustment, fully counterclockwise. The voltmeter should
read approximately +3 Vdc.
6. Disconnect the voltmeter.