Icom IC-7700 - Manual (Page 149)

10-7
10
ANTENNA TUNER OPERATION
■
Antenna tuner operation (continued)
• PTT TUNER START
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
” operation and activates for the first
transmission on a new frequency.
This function is turned ON in set mode. (p. 12-13).
• 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 antenna
tuner for their respective operations.
D 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 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 to turn the antenna tuner ON.
w Select CW mode.
e Turn OFF the break-in function. (p. 6-3)
r Push to set to the transmit condition.
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
TRANSMIT
TUNER
TUNER