User manual
EXPERT 2K-FA
Pag. 23 of 23 Issue 2 – May 2011
8. TUNER (ATU)
The amplifier has an automatic tuner that handles load mismatches up to 3:1 VSWR
(2.5:1 for 6 m).
The amplifier contains a look-up table with all the permitted bands.
For tuner management, antenna data and other working data are stored.
Every band has a sub-band set, and for each of those, data related to the antenna and
auto-ATU tuning is stored.
The CAT and the frequency counter detect the operating frequency and the correct
sub-band. Thanks to the stored data, the tuner and the antenna are automatically set
correctly.
For every input there is a different table. If two exciters are connected at the same time,
each exciter can have different configurations.
It is possible to use the two different tables when the amplifier operates at two different
locations. In fact it is possible to use the INPUT 1 at one and INPUT 2 on the other.
In this way a repeated reprogramming is not needed.
Furthermore, table driven management is useful to inhibit operation of the amplifier, for
instance when an antenna for a particular band is not available.
All auto-tuner functions remain, on standby, while
using the transceiver only.
Setting of the match data to write to the tables is performed automatically by pressing
the [TUNE] key.
The system will then find the correct match for minimum SWR.
To achieve a better match than that achieved with the automatic tune routine (most
unlikely) it is possible to set the tuning manually by using the keys [
◄
C], [C
►
], [
◄
L],
[L
►
].
When manual tuning has been performed, it is possible to read the tuning value, the
working frequency and the associated sub-band on the appropriate screen page.
Both the types of tuning are always implemented
in “STANDBY“ state.
Before beginning the matching process, the tuner measures the SWR of the system
cable / antenna
.
if it is greater than 3.5:1, the procedure does not begin
and an alarm is
given.
It is possible to bypass the tuner with a specific command, in order to use an external
tuner.
NEVER USE THE INTERNAL TUNER WITH AN EXTERNAL ONE, it could seriously
damage the linear.
IF YOU WANT USE AN EXTERNAL TUNER, DISABLE THE INTERNAL ONE.
The internal tuner may be disabled:
- Totally.
- For single band.
- For single band only with a specific antenna.
It 's always automatically disabled:
- With the only receiving antenna set
- With tuneable antenna set.
Note: the tuner, like all analog circuits, introduces a loss (0.8 dB max.) that may vary with
tuning conditions. The power meter of the amplifier does not show this loss as the
power is measured at the tuner input where the load resistance is always constant
(50 ohm).