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User's Manual | ACOM 2020S | 1.8-54 MHz Linear Power Amplifier
Page 34 of 76 | S e c t i o n FIRST POWER-ON, CONTROL SYSTEM, AND INITIAL CHECK June 2022
3.6.
Test Transmission
To make sure that you have installed the amplifier correctly, make a test transmission as described below.
Repeat these tests for each band and antenna to be used, as well as after installing a new or repaired
antenna, antenna switch, tuner, and / or the connecting cables.
a) Check of RF bypass path of a non-driven amplifier
For this check the amplifier must be completely installed and connected according to Section
2 INSTALLATION
, but not powered by the mains, i.e., the main rocker switch on the rear panel (see
Figure 2-3
| Amplifier rear panel - Connections ,
Pos. 3) must be turned off. In any case the red LED on amplifier's front
panel (
Figure 3-1 | Amplifier and RCU Front panels - Controls and Readouts
, (Pos. (a)), as well as the red LAD on
RCU's front panel must be dark for this test.
First, check if the transceiver's reception is normal. If you observe a significant worsening of reception, first
check for a problem in the coaxial connections to the amplifier (see Sections
2.4.1.d) RF INPUT connector
and
2.4.1.e) RF OUTPUT connector
, and
Figure 2-3 | Amplifier rear panel - Connections
, Pos. (d) and (e)). Be sure to
connect to the amplifier output an antenna having good SWR in the band being tested.
Provided the reception is normal, prepare the transceiver as follows:
•
Select a continuous carrier mode (CW, RTTY, FM);
•
Switch the microphone off (decrease the mic gain), disable FSK;
•
Reduce the output power control to a minimum;
•
Select a suitable indication so that you can watch the RF power and SWR at the transceiver
output;
•
If the transceiver has a built-in antenna tuner - switch it off.
Now in RECEIVE mode select a frequency which is not occupied at the moment and press shortly the PTT or
TX key while watching the transceiver output power and the SWR readings. If either the power or SWR at
the transceiver output are too high (over 5 W or SWR over 2) release the key and check for the reason as
follows:
•
Check again whether the power control is set at minimum;
•
Check whether the frequency is within the operating range of the selected antenna;
•
Check the good working order of the coaxial cables, connectors, and feed lines from the
transceiver antenna jack through the amplifier bypass path (RF INPUT - RF OUTPUT), the
antenna switch or external tuner (if there is one) to the BALUN transformer, and the antenna
itself.
If the power and SWR are as expected, transmit again and while watching the power and the SWR readings,
increase transceiver power gradually from minimum to maximum (but not more than 200 W, in order to
not overload the RF by-pass circuit of the amplifier).
If SWR remains below 2 (preferably below 1.5) at the last test, decrease the power from the transceiver to
minimum again and continue with the next check-up.