Wayne.B wrote in
:

I've had an Icom 802 SSB with AT140 tuner installed on the boat for
over 4 years now. It uses the more or less standard 23 ft whip
antenna and has the same ground system that the old SSB had which is
alleged to be a copper strap running down to the bonding system. It
has worked fairly well up until recently but now seems to be
transmitting weakly and the control panel is indicating a high SWR.
Nothing has changed as far as I can determine and all connections seem
to be tight and corrosion free. I'm suspecting that the tuner is not
working properly but other than buying and installing a new AT140, I
can't think of any way to trouble shoot this issue.

Any suggestions?


A 23' whip is resonant on:

234/Mhz = feet for a 1/4 wave antenna.

234/23' = 10.17 Mhz or something close to that.

As you approach this frequency, no tuner is really required so press the
button to bypass the tuner, taking it out of the circuit.

You can make the M802 transmit on any frequency between 2 and 30 Mhz.
Hee hee....I found my post from 3/2008 when I looked for the commands:

To open up the transmitter so it will transmit on ANY frequency from 2-
30
Mhz, simply hold down the MODE and TX buttons with the M800 powered off,
then, while holding these buttons down, turn it on and it will toggle
into
full width transmit mode. To put it back into marine channels ONLY just
repeat the procedure.

After opening up the transmitter so you can transmit anywhere, tune the
radio in the Mhz mode to 10.17 Mhz and see if it tells you the SWR is
very high when you key the mic and whistle into it so you produce RF
output on the SSB radio. Can you hear static and WWV on 10.000 Mhz
well? If not, the antenna isn't connected to the radio, somewhere.

If reception is not good around 10 Mhz, with the tuner bypassed, the
tuner isn't the trouble, probably. Bypass the coax cable laying in the
bilgewater with a new piece between the tuner and radio just laying on
the deck. Did that fix it?...bad coax.

If you still suspect the tuner, you can make up a coax cable with the
PL-259 connector for the radio on one end and just wires on the other.
Disconnect the tuner from the whip and connect the coax center conductor
directly to the 23' whip's feed point. Connect the shield to what you
think is the tuner ground strap, which, I assume, you've already
inspected for corrosion, good connections, open circuits. The whip
should work directly connected to the radio at some point around 10.17
Mhz, give or take half a megahertz. There should be a broad (in
frequency) drop in SWR near the antenna's natural resonant point around
10 Mhz. If there's not, hooked directly up with new coax bypassing the
whole normal feed system....the little conductor inside the 23' whip has
parted and is open.....or the ground system isn't there. Drop an anchor
over the side and let it almost touch the bottom on CHAIN rode. Use a
vice grip to clamp the shield of your coax to the chain at the base of
the 23' whip, making a SUPERGROUND in seawater for it. Test it again.
If you find the broad low SWR around 10 Mhz, the antenna is fine, the
boat's ground is crap. Anchor chain is nearly the perfect radio ground,
even all rusty like that, because it's so massive soaked in seawater.

Store that info away for emergencies, too. When you're using SSB and
they can't hear you, drop the anchor and hook it to the tuner ground and
your signal will double, almost every time. You'll have to RETUNE the
tuner to get a new tuning solution, though.

Hope this helps you find it. M802 is a nice radio but stupidly packaged
with its case left open so the sea air can get inside sucked in by the
fan to cool it and corrode the hell out of everything
inside...eventually. Icom knows better because the M602 is SEALED with
an external heat sink....\

================================================== =================

Oh, one more touch.....Icom made the stupidest decision putting a
pigtail with an open, unsealed cheap connector OUTSIDE the sealed tuner
to plug the control cable into. This is just WRONG! It'll corrode,
idiots! If this has happened to your installation, the tuner isn't
working and the SWR will stay high all over the place.

To correct this problem, unscrew the cover on the AT tuner and carefully
remove it without ripping the seal. Notice where this stupid pigtail
nonsense is soldered to the main tuner PC board on little solder loops
sticking up from the board. UNsolder the pigtail and cut the stupid
open plug/socket off the control cable. Throw the pigtail and
connectors overboard, just to show Icom you mean business. (We had a
ceremony, complete with Davy Jones, who was drunk as usual.) Now, feed
the control wire cable through the watertight connector after loosening
up the compression nut and tighten it down to seal it back up against
water intrusion. Skin back the insulation and solder the wires NOTING
THE SAME COLOR CODE CONNECTIONS AS THE PIGTAIL, directly to the solder
loops on the PC board inside the tuner. Problem solved. AT-140 will
last until the lightning hits it, now. Unsolder the wires to replace
it...not rocket science.
--
Larry

If that doesn't work, bring the boat to Charleston and I'll perform
magic on it. They all stood in awe around the speaker when the 3rd ham
station I contacted from right inside the crowded marina was in New
Zealand from the insulated backstay hooked up to the insulated triattic
between the masts on Lionheart...(c; We were on 20 meter ham band.

73 DE W4CSC/MM2