Icom IC-M802 Installing page 16

Troubleshooting marine SSB radio
R Medero March 2015 – Partially complete, still working on this doc
Low Transmit Power
1. Verify antenna connections are good – Check connections between tuner and antenna as any
connections exposed to elements will eventually fail.
Check coax connections between radio and tuner. Verify that they are snug and clean. Perform
continuity test by disconnecting both ends and verify no continuity between shield and center
conductors on one end (end A) then connect shield and center of other end (end B) together. Verify not
more than 10 ohms is measured on end A.
Whip antennas can fail and can be verified with SWR meter. Connected SWR meter between radio and
tuner, perform tune operation and verify SWR is low. Staring at top, remove one section of antenna at a
time including connection at base, and verify that SWR (without retuning) changes as each is removed.
2. Verify power to radio is good – Verify power at radio is good while transmitting. Set radio to high
power (if feature present) Measure voltage at as close to radio as practical while transmitting and
whistling into mic. Verify you have at least 12v. If large voltage change is observed it could be the
meter is sensitive to radio frequency interference, connections are resistive, wire is too small or too
long, or battery is weak. To help determine meter reading is true, connect 12v light bulb where meter is
connected and observe change in brilliance. Use different meter if you suspect reading is false.
3. Verify tuner is operating – Listen to tuner when tuner is turned on. On most rigs such as ICOM this is
when the transceiver is turned on. You should hear relays in the tuner make a click sound. This verifies
the tuner is powered up. If no sound is heard verify tuner control cable connections. On ICOM radios
verify there is near 12 volts between the red and black wires. NOTE: Take care to not connect the red
wire to any other wire as this can blow a fuse in or damage the transceiver or tuner. Another method to
verify tuner is powered, set radio a frequency where a weak signal is heard (can use static if weak
station not found). Disconnect tuner control cable while listing and verify signal level decreases.
Reconnect control cable and very signal level increases.
If radio has a tune button verify that radio momentarily indicates it is transmitting when button is
pressed. If it does not, verify tuner control cable connections. On ICOM radio: Momentarily connect
green(key) wire to black(GND) wire and verify radio indicates transmitting while connection is made. If
it does not then problem is in cable or radio. Momentarily connect white(start) wire to black(GND) wire
and verify radio indicates transmitting while connection is made. If it does not then problem is in cable
or tuner. When tune button is pressed you should hear relays in the tuner click.
On ICOM M802 the display will indicate when tuning is successful by indicating TUNE in upper area of
the display. If not successful it will indicate THRU. If radio is indicating it is transmitting when tune