User Manual

Page 19 of 34
When you rely on an automatic change with the built-in frequency counter, it is a good practice (although not
compulsory), that selecting a new band the operator makes one quite short “preliminary” transmission (100ms
is enough) and leave a pause (also short) before the main transmission. During this pause the amplifier will
change the band according to the new frequency without RF power, after which the operator can continue his
operation as usual.
If the new frequency is within the range admissible for the amplifier but outside the currently selected band, the
amplifier control unit temporarily blocks transmission while the change of the harmonics filter for the respective
new band lasts, after which the transmission continues on the new frequency as usual.
If the new frequency is out of the range admissible for the amplifier (S. 8-1(a)), the transmission request is
denied and the following fault message appears on the screen:
“FREQUENCY OUT OF RANGE”
The standard frequency bands within which all amplifier parameters are guaranteed are listed in S. 8-1(a)).
Extension or changes of the bands could be negotiated with the manufacturer.
4-3. Change of antennas and operation with an external antenna tuner
At a band change or moving frequency from one to the other end of the band it may be necessary that you
change the antenna and eventually retune the antenna tuner (unless your antenna is a multibander and / or is
broadband enough).
At antenna SWR over 1.5:1, it is preferable that you use an external tuner. Usually the procedure for retuning
the tuner requires a continuous carrier signal and small power. In such a case, go to the STBY mode of the
amplifier and feed the power necessary for tuning from the transceiver only. After you have retuned the
antenna tuner on the new operating frequency or with the new antenna, return to the Operate mode and adjust
again the drive power according to the operating mode used – S. 3-6(f)).
4-4. Cooling and fans operation; modes with increased heat loading
During operation in modes with increased heat loading (continuous carrier, RTTY, SSTV, some digital modes,
and others), the amplifier itself will monitor its temperature regime, automatically increasing or decreasing fans
velocity depending on the loading and ambient conditions (temperature, humidity, atmospheric pressure etc.).
4-5. Monitoring the amplifier operating regime
Because of the availability of a continuously operating protection system in the amplifier (S. 4-6), the operator is
not required to monitor its regime regularly. However, whenever he wishes, he can digitally measure the 11
most important parameters connected with the amplifier operating regime. Besides this, the operator can select
two of them arbitrarily for indication also in the basic screen (Fig. 3-2, S. 5-1).
4-6. Automatic protection system
The control unit (S. 7-3(b)) keeps track with most amplifier analog and logic signals in all modes. Monitored are,
for example, the control signal receive / transmit, the output relay contact status and switching times, the RF
drive frequency and drive power (the input power), the DC current and the DC voltage on the drains of the final
transistors, the bias of their gates and the temperature of their heat sink, the temperature of the main
components in the power supply unit, the forward and reflected power at the RF output, and others. Besides
this, monitored and assessed are some derivative parameters, such as the power gain, the SWR, the heat
power dynamically dissipated by the final transistors etc.
If anything abnormal has been found out in an arbitrary moment, the amplifier will assess the risk of the
situation and can use three levels of protection according to the problem nature and seriousness, as described
in items (a) to (c) below. Every event is accompanied by a warning text on the screen (Fig. 4-1), which is
blinking to attract the operator’s attention. Besides this, a sound signal is produced, whose volume, can be
reduced by the operator if he so wishes – menu “USER PREFERENCES” – Fig. 5-4.