R.V.R. Elettronica HC4, User Manual

Page: 38 / 72

HC4
34 / 34 User Manual Rev. 1.0L - 01/04/02
Trimmer TR7 adjustment
• The trimmer TR7 must be turned completely counter-clockwise, to protect the
input channel to the CPU.
FOLBACK intervention adjustment
• Be sure that the exciter is not operative.
• Measure the voltage on the PIN1 of JP7 on the power supply card with a
multimeter, than rotate the trimmer TR9 to obtain a voltage of 0V.
Forward power reading adjustment
• Increase to 4000W at 98MHz, using as a reference the reading on the wattmeter
that possibly has been connected at the end of the attenuation chain at the RF
output.
• Rotate TR1 to read on the display the same value measured with the wattmeter.
Reflected power adjustment
• Apply an unbalanced load in series with a 50 Ohm load and apply in series a
by-pass wattmeter BIRD.
• Increase slowly the exciter power to obtain a reflected power of 400W at 98MHz.
• Adjust TR2 to read on the display the same value measured with the wattmeter.
VPA reading adjustment
• For the hybrid combiner this reading is disabled.
IPA measurement adjustment
• For the hybrid combiner this reading is disabled.
Input power reading adjustment
• Connect to the RF input a by-pass wattmeter BIRD with a full-scale of 10 W.
• Connect a 50Ohm load to the exit and increase slowly the exciter power to
obtain 5W on the instrument in series to the input.
• Rotate TR3 on the CPU assembly to read on the display the correct value
measured with the wattmeter.