Icom IC-M802 Installing page 17

button is pressed, but not indication that tune operation succeeded, check coax connections between
radio and tuner and antenna and ground connections on tuner.
Tune succeeds on some frequencies and not others. Very ground is good (see counterpoise info in other
doc's), antenna connections are good, and antenna length including wire from tuner to antenna is not
near ½ wave length (about 502/frequencyInMegaHertz). If you suspect it is the near ½ wave problem
then add few feet of wire to antenna. Then verify other frequencies tune ok.
4. Antenna connections and tuner operation seem OK, but signal output is still low, verify radio is
drawing expect amperage while transmitting loud audio (or CW if you know how to do that). A 100 watt
radio should draw more than 15amps (20a for 150w radio). Verify radio is set to highest power and
whistle in the mic while transmitting and note the amperage draw. If amperage is too low, the cause
could be poor antenna match, voltage at radio too low while transmitting, not enough audio drive (bad
mic or mic gain set too low) or bad component in radio. If amperage is as expected, it is unlikely issue is
with radio or tuner, check antenna connection, GTO wire and tuner ground.
Difficulty Receiving
1. Verify receive (RF) gain is set to maximum, squelch if off, audio frequency based filtering is off (DSP
filtering found on some ham rigs).
2. Electrical RF noise (interference) is the most usual cause of issues with receiving. RF noise is
commonly generated by electronic stuff you have on board, onboard neighboring vessel or on land.
Refrigerators, solar panel charge controllers, AC charges and inverters are among the worst offenders,
but can be most anything from LED or CF lights, to watermaker controls. Most radios have signal
strength indicators that are useful for measuring RF noise level. On the IC-M802 for example there is a
bar graph in the lower left of the display. Under good noise conditions there should be only 1 or 2 bars
illuminated when no one is transmitting. While sometimes naturally occurring noise can be higher, if 3 or
more bars are illuminated that is an indication of local electrical noise.
RF interference can sound like static or it can sound like some man made signal. Also the interfering
noise can come as conditions change in the device that is generation the noise. The controller for DC
refrigeration is one example of a device that sometimes interferes on frequencies we commonly use. The
noise from this device can sound like data or Morse code signals and will drift in and out of frequency
you are monitoring.
To locate a noise source on your vessel wait for the frequency to be clear (no one transmitting) , observe
the signal level indicator while listening to the noise. Remove power from (NOT JUST TURN OFF) all
electrical devices while observing change in noise. Then power each on one by one again observing
change in noise. If there is no way to disconnect solar panels from controller you can try placing heave
cloth over the panel to shade the sun.
3. A good transmitting antenna is also good for receive. You can verify your antenna using your
transmitter, see steps above in Low Transmit Power
4. While usually not necessary tuning your antenna will improve reception. You might find that once
tuned and a band such as 4mHz then switching to the 8mHz band for example, receive signals are very