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FLEX-3000 Transceiver
»
Antenna Tuning Unit (ATU)
»
FLEX-3000 ATU Operation with PowerSDR 1.x
FLEX-3000 ATU Operation with PowerSDR 1.x
FLEX-3000 ATU Operation with PowerSDR 1.x
FLEX-3000 ATU Operation with
PowerSDR
1.x
System Dependencies
Minimum
PowerSDR
Version:
1.18.0
Applicable Hardware:
FLEX-3000
Content provided by:
FlexRadio Systems Engineering
The FLEX-3000 has an integrated Antenna Tuning Unit (ATU) is a standard feature. The ATU will tune a variety of unbalanced antenna systems (
coax
) that facilitates its use with multi-band antennas where the
SWR
is less than 3.0:1. When used with an appropriate balun, balanced antenna systems can be utilized also. The ATU, when tuned and enabled, is also in the
RX
signal path further enhancing reception acting as a preselector. An ATU bypass function will completely remove the ATU from both the
TX
and
RX
signal paths. All ATU functions are automatically controlled using FlexRadio
PowerSDR
as well as having manual control of the ATU.
FLEX-3000 ATU Specifications
Network Type: Switched "L"
Impedance
Range: 17 to 150 ohms
Power Rating: 100 watts 160-6m
Maximum
SWR
3.0:1
There are two
PowerSDR
1.x front panel controls used with the FLEX-3000 ATU. The are the Bypass control (
BYP
) and the ATU enable control (
ATU
).
To initiate the tuning processes, click on the
ATU
button. The
ATU
,
TUN
(tune) and
MOX
(
PTT
) buttons will all turn yellow indicating that the ATU tuning process has started.
The first step in the ATU tuning is to measure the actual
impedance
of the antenna system to determine the baseline
SWR
.
If
the baseline
SWR
is greater than 1.1:1 and less than 3.0:1, then the ATU begins the tuning process. You will hear a series of relay clicks and the
transmitter
will send a low power signal to the antenna as the ATU switches in different values of
inductance
and capacitance trying to compensate for a complex
impedance
that varies from 50 ohms resistive. This activity should only take several seconds to complete.
If
a better
impedance
match was found within the operational range of the ATU (1:1 to 3:1), the
ATU
button will turn from
YELLOW
to
GREEN
, indicating that the ATU is operational and in the
RF
signal path (both
TX
and
RX
).
If
the ATU could
*not*
find a better match than the baseline
SWR
and
it is within the operational range of the ATU
(1:1 to 3:1), the
ATU
button will turn from
YELLOW
to off and the
BYP
button will turn
YELLOW
, indicating that the ATU has been bypassed and is
*not*
in the
RF
signal path (both
TX
and
RX
).
If
the ATU determines that the baseline
SWR
is greater than 3.0:1
, the ATU button will immediately turn
RED
indicating an error condition. The error condition is that a
SWR
greater than 3.0:1
exceeds the operational parameters of the power amplified (
PA
)
The ATU is
*not*
engaged and is
*not*
in the
RF
signal path. In essence, it is in
BYPASS mode
, but the ATU button remains
RED
to provide a visual cue that
you should not transmit using this antenna system until the
SWR
is less than 3.0:1.
NOTE: The TUN button is used for
manually
generating a low
RF
signal used for external ATUs and is not utilized with the FLEX-3000 internal ATU.
To fully illustrate the FLEX-3000 ATU, a few examples are provided below.
ATU Tuning Examples:
#1: The baseline
impedance
of the antenna system is 1.4:1
You engage the ATU and it can not add
inductance
or capacitance to produce a better match than 1.4:1. Since the final
impedance
is less than 3:1
and
is within the normal operating range of the
PA
, the
BYPASS
button will be
yellow
, indicating that the ATU is in bypass mode.
#2: The baseline
impedance
of the antenna system is 1.7:1
You engage the ATU and it
*can*
add
inductance
or capacitance to produce a better match, say 1.1:1. The
ATU
button will be
green
indicating that the ATU found a match and is operation (in the
RF
signal path).
#3: The baseline
impedance
of the antenna system is 3.5:1
You engage the ATU and it
cannot
add
inductance
or capacitance to produce a better match. Since the baseline
impedance
is greater than 3:1 and is
*not*
within the normal operating range of the
PA
, the ATU button is RED, indicating the there is a high
SWR
error condition. The ATU is actually in bypass mode and is not in the
RF
signal path nor it the signal path "blocked" due to the excessive
SWR
that the ATU determined. You can still transmit, but the
SWR
exceeds what is acceptable for the
PA
.
This KB article may reference additional files that are available on the FlexRadio Systems web site Downloads page. Please use the URL(s) below to download the referenced materials.
An Adobe Acrobat Reader may be required to open the file. You can download Adobe Acrobat from here.
KB Source Document(s):
None Referenced
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Details
Last Modified:
Monday, April 27, 2009
Last Modified By:
Administrator
Type:
HOWTO
Rated 5 stars based on 1 vote
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