D If The Tuner Cannot Tune The Antenna - Icom IC-7700 Instruction Manual

■ Antenna tuner operation (continued)
• PTT TUNER START
• Antenna tuner of the IC-PW1
D D If the tuner cannot tune the antenna
ANTENNA TUNER OPERATION
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 "push
and hold " operation and activates for the first
TUNER
transmission on a new frequency.
This function is controlled in set mode. (p. 12-13).
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 antenna
tuner for their respective operations.
Check the following and try again:
• the [ANT] connector selection.
• the antenna connection and feedline.
• the untuned antenna SWR.
than 2.5:1 for 50 MHz band)
• the transmit power.
• 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
to turn the antenna tuner ON.
TUNER
w Select CW mode.
e Turn OFF the break-in function. (p. 6-3)
r Push
to set to the transmit condition.
TRANSMIT
t Set 3.55 MHz and key down.
y Set 3.80 MHz and key down.
u Push
to return to the receive condition.
TRANSMIT
10-7
(Less than 3:1 for HF bands; Less
(8 W for HF bands; 15 W for 50 MHz band)
10