Icom IC-7800 - D if the Tuner Cannot Tune the Antenna

10-6
■ 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 “hold
down [TUNER]” operation and activates for the first
transmission on a new frequency.
This function is turned ON in set mode. (p. 12-16).
• 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-7800’s tuner. After tuning is com-
pleted, turn the internal tuner ON. Otherwise, both tun-
ers tune simultaneously and correct tuning may not be
obtained.
See the instruction manual included with each antenna
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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 Set 3.55 MHz and hold down [TUNER] for 1 second to
start manual tuning.
w Set 3.80 MHz and hold down [TUNER] for 1 second to
start manual tuning.
10
ANTENNA TUNER OPERATION