D If The Tuner Cannot Tune The Antenna - Icom IC-7800 Instruction Manual

10
ANTENNA TUNER OPERATION
I Antenna tuner operation (continued)
• PTT TUNER START
• Antenna tuner of the IC-PW1
D D If the tuner cannot tune the antenna
The tuner is always tuned when the PTT is pushed
after the frequency is changed (more than 1% from
last-tuned frequency). This function removes the "push
and hold [TUNER]" operation and activates for the first
transmission on a new frequency.
This function is turned ON in set mode. (p. 12-15).
When using an external antenna tuner such as the IC-
PW1's tuner, tune with the external antenna tuner, and
turn OFF the IC-7800'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 low bands, have a narrow
bandwidth. These antennas may not be tuned at the edge
of their bandwidth, therefore, tune such an antenna as fol-
lows:
[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.
10-6
(Less than 3:1 for HF bands; Less
(8 W for HF bands; 15 W for 50 MHz band)