10-7
10
ANTENNA TUNER OPERATION
■
Antenna tuner operation (continued)
• PTT TUNER START
The tuner is always re-tuned when the PTT is pushed
after the frequency is changed (more than 1% from
last-tuned frequency). This function replaces the “hold
down
TUNER
” operation and activates for the first
transmission on a new frequency.
This function is controlled in set mode. (p. 12-14).
• Antenna tuner of the IC-PW1
When using an external antenna tuner such as the
IC-PW1’s tuner, tune with the external antenna tuner,
and turn OFF the IC-7700’s tuner. After tuning is com-
pleted, turn the internal tuner ON. Otherwise, both
tuners tune simultaneously and correct tuning may
not be obtained.
See the instruction manual included with each an-
tenna tuner for their respective operations.
D
If the tuner cannot tune the antenna
Check the following and try again:
• the [ANT] connector selection.
• the antenna connection and feedline.
• the untuned antenna SWR.
(Less than 3:1 for HF bands; Less
than 2.5:1 for 50 MHz band)
• the transmit power.
(8 W for HF bands; 15 W for 50 MHz band)
• the power source voltage/capacity.
If the tuner cannot reduce the SWR to less than 1.5:1
after checking the above, perform the following:
• repeat manual tuning several times.
• tune with a 50
Ω
dummy load and re-tune the antenna.
• turn power OFF and ON.
• adjust the antenna feedline length.
(This is effective for higher frequencies in some cases.)
• Some antennas, especially for the low bands, have a nar
-
row bandwidth. These antennas may not be tuned beyond
the edge of their operating 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.
q
Push
TUNER
to turn the antenna tuner ON.
w
Select CW mode.
e
Turn OFF the break-in function. (p. 6-3)
r
Push
TRANSMIT
to set to the transmit condition.
t
Set 3.55 MHz and key down.
y
Set 3.80 MHz and key down.
u
Push
TRANSMIT
to return to the receive condition.
