Icom IC-746 [61/88] Internal antenna tuner

Icom IC-746 [61/88] Internal antenna tuner
59
9
INTERNAL ANTENNA TUNER
9-1
Before operating
9-2
Tuner operation
Make sure that output power on the HF bands is
higher than 8 W; on the 50 MHz band, higher than
15 W.
Push [TUNER] to turn the internal antenna tuner
ON. (See p. 3!5RF POWER CONTROL.)
The antenna is tuned automatically when the SWR is
higher than 1.5:1.
When the tuner is ON, TUNER appears in the display.
[TUNER]
The internal automatic antenna tuner matches the
transceiver to the connected antenna automatically.
Once the tuner matches an antenna, the variable ca-
pacitor angles are memorized as a preset point for
each frequency range (100 kHz steps). Therefore,
when you change the frequency range, the variable ca-
pacitors are automatically preset to the memorized
point. (See p. 6219 Auto tune.)
MANUAL TUNING
During SSB operation at low voice levels, the internal
tuner may not be tuned correctly. In such cases, man-
ual tuning is helpful.
Push [TUNER] for 2 sec. to start manual tuning.
During manual tuning, TUNE”flashes.
If the tuner cannot reduce the SWR to less than 1.5:1
after 20 sec. of tuning, [TUNE] disappears and through
is selected.
IF THE TUNER CANNOT TUNE THE
ANTENNA
Check the unaltered antenna SWR (less than 3:1 for
HF bands; less than 2.5:1 for 50 MHz band).
Repeat manual tuning several times.
Tune with a 50 dummy load and re-tune the an-
tenna.
Turn power OFF and ON.
Adjust the antenna cable length (this is effective for
higher frequencies in some cases).
Some antennas, especially for low bands, have a nar-
row band width.These antennas may not be tuned at
the edge of their bandwidth, therefore, tune such an
antenna as follows:
[EXAMPLE]: Suppose you have an antenna which has
an SWR of 1.5:1 at 3.55 MHz and an SWR of 3:1 at
3.8 MHz.
Push [TUNER] to turn the antenna tuner ON.
Select CW mode.
Turn OFF the break-in function (p. 44).
Push [TRANSMIT] to set the transmit condition.
Set 3.55 MHz and key down.
Set 3.8 MHz and key up.
Push [TRANSMIT] to return to the receive condition.
NOTES
The internal antenna tuner can only tune the HF and
50 MHz bandsthe 144 MHz band cannot be tuned.
DO NOT transmit if no antenna is connected to
[ANT1] or [ANT2].
When 2 antennas are connected, select the antenna
to be used with [ANT].
If the SWR is higher than about 1.5:1 when tuning
above 100 kHz on an antennas preset point, push
[TUNER] for 2 sec. to start manual tuning.
The internal tuner may not be able to tune in AM
mode. In such cases, push [TUNER] for 2 sec. to
manually tune.

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