Instruction Manual

DE
DANIELS
ELECTRONICS
VT-3A130 Amplifier Instruction Manual 3-3
9. Apply a 1000 Hz signal with 0.200 Vrms level to the amplifier's
MODULATION INPUT and adjust AUDIO ADJUST pot R35 to obtain 90% of AM
modulation.
10. Adjust the DISTORTION ADJUST pot R14 to the lowest distortion (less than 5%)
11. Change the RF signal frequency to 128 MHz, 138 MHz and control the Modulation
Level and Output Power (with no modulation).
12. Re-adjust the AUDIO ADJUST pot R35 (if it necessarily) so that the modulation level
do not exceed 90% at 128 MHz and 138 MHz frequencies.
13. Re-adjust the POWER ADJUST pot R19 (if it necessarily) to achieve a minimum
tolerance of the output power (4 Watt +/- 1dB).
3.5.3 Changing Power Output
The power amplifier's carrier output level can be adjusted from 1.0 to 4.0 watts. To
change the RF output level, follow the procedures described below.
1. Apply power to the amplifier's +13.8 Vdc and +9.5Vdc pins. The +9.5 Vdc power
supply must be well regulated.
2. Connect the amplifier's antenna output connector to the type N input of the radio
communications test set through a short section of low loss 50 Ω coaxial cable.
3. The amplifier requires -5 dBm to 5 dBm of RF power
4. Turn on the amplifier by applying a ground to the AMPLIFIER ENABLE pin.
5. Adjust the POWER ADJUST pot R19 to achieve the desired RF carrier power output
between 1.0 Watt and 4.0 Watt.
6. Apply a 1000 Hz signal with 0.200Vrms level to the power amplifier's
MODULATION INPUT and adjust AUDIO ADJUST pot R35 to obtain 90% of modulation.