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ICOM-M802 SSB

W

Wet-n-Wild Bill

Jan 1, 1970
0
I'm looking at SSB for my boat the ICOM-M802 has two RF conectors one to
the Autotuner and the other for DSC Receive.

If i opt to only use one antenna for thr Autotuner AT-140. Will i be able
to use the DSC function of my radio? if so with what linitations?

Bill
 
B

Bjarke Christensen

Jan 1, 1970
0
hmmm wrong track I guess.....

802 is an HF only device. The reason for the two RF connectors is because
it's a class E DSC where you have to be able to receive DSC sentences
*while* transmitting. Therefore it's has to have two antenna's.

Remeber that even if we "spare-time-sailors" most often use VHF ch 70 for
DSC, it's quite possible to run DSC on HF.

/Bjarke
 
L

Larry

Jan 1, 1970
0
If i opt to only use one antenna for thr Autotuner AT-140. Will i be
able to use the DSC function of my radio? if so with what linitations?

Nope. M802 requires one transmitting antenna through the autotuner and
another receiving antenna for its separately-scanning DSC receiver. Ours
on Lionheart is hooked up to the handrail bolt through the toerail. It was
cheap and dirty as there's no room for another antenna, like a whip, that
wouldn't be in the way of sailing it. I was going to change it, but it
works just fine, what little actual HF DSC traffic is ever transmitted for
it to receive.

If you don't hook up the 2nd receive antenna, you won't have HF DSC receive
scanner capability.

DO NOT TRY TO PUT A COAX T INTO THE TRANSMIT LINE AND BLOW THE HELL OUT OF
IT! I've seen two stupids, already, who did. It isn't pretty at 150 watts
into the DSC receiver...
 
L

Larry

Jan 1, 1970
0
You could get a diplexer to connect both antenna ports to one antenna

Sue him when you blow the hell out of it. These diplexers are for using
two radios on WIDELY SPACED-IN-FREQUENCY DIFFERENT BANDS! THEY DO NOT
DIPLEX WHEN BOTH RECEIVERS ARE ON THE SAME HF BANDS!

This nonsense will blow the DSC receiver's front end....I guarantee it.

DO NOT HOOK BOTH COAX CONNECTORS TOGETHER THROUGH ANYTHING!!

Geez....
 
Y

You

Jan 1, 1970
0
Ted said:


that could solve Purple_stars delema, but wouldn't solve the OP's
original problem, or answer his question......

The answer to the OP's question, is NO, you need the second antenna
for DSC to function.....
 
L

Larry

Jan 1, 1970
0
I was responding to a comment about the two antenna connectors being
designed for separate HF and VHF bands. That misconception about the
M802 has been corrected. The ports on the diplexers I listed are band
isolated so if you did connect it to the M802 it wouldn't work
properly but would not "blow the DSC receiver's front end". You
should stop and think before you fuss.

If we are helping the "average boater", who is not an electronics person,
any response to this thread about diplexers may lead him astray to putting
a diplexer in his antenna line, as this thread had nothing, whatsoever, to
do with VHF or AM/FM radio or diplexers.

I'd just hate to see him try a diplexer to such a nice radio as the M802,
in spite of the M802's shortcomings of the wide open cabinet with the
internal cooling fan sucking sea air into the circuits, a really stupid
design with its chinzy cable connectors, to boot.

He was looking for "the easy way out", some method of connecting those two
tempting connectors together to one cable....a path YOU were providing him
with I pray he ignores...

I don't even want him to put up a receiving antenna anywhere near the
transmitter's antenna for fear of taking out the DSC front end, which is
broad tuned for the whole HF band.
 
W

Wet-n-Wild Bill

Jan 1, 1970
0
Thanks guy for the info! Since the M802 is HF along with the DSC. What coud
i do for a receiving antenna?

My boat which is all aluminum makes a great ground plane. On the Xmit/Rec
side i'm planning on a 23' whip. As for the DSC REC antenna, can i use a
shorter antenna, what options do i have to run a long wire, can i lay it in
an insulated surface in a zigzag pattern. Or must it be pulled straight from
the balun?

Bill
 
T

ted

Jan 1, 1970
0
You said:
that could solve Purple_stars delema, but wouldn't solve the OP's
original problem, or answer his question......

The answer to the OP's question, is NO, you need the second antenna
for DSC to function.....

agreed
 
L

Larry

Jan 1, 1970
0
My boat which is all aluminum makes a great ground plane. On the
Xmit/Rec
side i'm planning on a 23' whip. As for the DSC REC antenna, can i use
a shorter antenna, what options do i have to run a long wire, can i
lay it in an insulated surface in a zigzag pattern. Or must it be
pulled straight from the balun?

You could use another 23' whip away from the transmitter's whip. The
receive antenna is not tuned. The 23' whip is naturally resonant around 10
Mhz, so that would be great for the whole HF band, better around 8-12 where
most of the receiving is done, anyway. Just ground the shield of the coax
to the hull and the center conductor to the whip, isolated from the hull.
 
S

Steve Thomas

Jan 1, 1970
0
If one didn't care about receiving DSC during transmit, wouldn't it be
possible to use an antenna relay, or a manual coaxial switch? I have never
seen the latter, but I am sure they must exist. There is little enough room
for hf antennas on a sailboat, but I really like your hand rail solution for
GRP boats.
 
B

Bjarke Christensen

Jan 1, 1970
0
Don't mess around with switches. To much risc. Check if it can be confugured
for a lower rate DSC (class D) where send/receive takes place on the same
(primary) antenna.

Bjarke
 
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