Acom 500S, User Manual

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User's Manual | ACOM 500S | 160-4 m Linear Power Amplifier
Page 32 of 66 | S e c t i o n FIRST POWER-ON, CONTROL SYSTEM, AND INITIAL CHECK March 2023
•
RX mode must change to TX;
•
The reflected power must read below 20 W;
•
The forward power must read between 20 and 150 W with minimum drive power from the
transceiver (between 1 and 5 W).
If the above test goes normally, push briefly the PTT once again, this time watching the transceiver's SWR
reading (i.e., the input SWR of the amplifier) - this must be below 1.5.
If the SWR to the transceiver is higher than 1.5, check the coaxial cable between transceiver's output and
amplifier's input socket (see Section
2.4.d) RF INPUT connector
).
e) Setting of drive level and typical operation
After successfully passing of the above tests push PTT or CW key for several seconds, watching the forward
and reflected power. Increase the drive power until the forward power bar graph and digital readout reach
500 W.
Upon reaching 500 W forward power check the following parameters (continuous carrier operation):
•
The reflected power must not exceed ~55 W (for SWR 2:1) or better still to be below 20 W (for
SWR 1.5:1);
•
PA DC CURRENT must be between 12 and 18 A; it is normal that the current varies within these
limits when changing operating frequency and antenna impedance;
•
PA DC VOLTAGE must be within 60-63 V;
•
The transceiver's SWR reading must be below 1.5.
Enter the MEASURE menu (see
Figure 5-2 | Menu AMP MEASURE
) and check:
•
Т he drive power from the transceiver must be between 15 W and 25 W;
•
PA BIAS, which must be between 2.1 and 2.9 V;
•
PA TEMPERATURE, which must be between the ambient and 95
o
C (203
o
F), depending on the
power level and the duration of transmission.
f) Elimination of electromagnetic compatibility (EMC) problems
If you use an amplifier for the first time in your shack, you may need to make some improvements in the
setup. It is possible you might experience tingling from metallic objects due to the stronger radiated RF field.
It could affect the operation of your station or systems outside, if they are too sensitive - typical examples
are the microphone, CW keyer, computer keyboard or mouse, as well as TV receivers, Hi-Fi devices, intercom
or telephone setups and others.
For instance, induction of RF currents into the microphone, CW keyer or computer keyboard, may lead to
distortion in the peaks or relaxation oscillation in SSB mode, "sticking" or breaking off the dots or dashes
from a Morse keyer, or garbling computer screen images. For the elimination of such problems, we
recommend that you take the following general measures:
•
Minimize the radiation from the feed lines by reducing the common mode currents in them,
improve the balance of antennas and feedlines;