Visit our Popular Forums

greenschooner · 20-12-2020, 07:07

Hi folks,

i am about to install my used ICOM M802 on my wooden schooner.
Regarding the ground I decided to use the KISS SSB counterpoise.
I keep you updated on that one.
Looking thru the installation guideline from ICOM they say you should connect
the transceiver directly to the battery thru the supplied cable including the fuse.
On the other hand they say you should disconnect the the M802 from the battery when at anchor
so the transceiver can not drain the battery due to the “high-stability oven-heater type crystal oscillator”.
Thinking about that I plan to use a remote battery switch (or relais )which can be switched remotely from the switch panel at the nav station.
Anybody have any experience with that?
One of topmast shrouds will serve as a “backstay antenna” as we do have running backstays (45’ isolated).
On the plus side I think with the antenna more upright as a backstay it should transmit less energy into the water.

Merry Christmas and a happy new year, stay safe!

Dominic

Telesail · 20-12-2020, 07:14

We run our SSB through the main switch panel at the nav station for the reasons suggested. No problem with that for us.

svMarite · 20-12-2020, 10:38

Your comment on vertical antenna makes me scratch my head. I used a homemade 1/4 wavelength with ceramic balls connected via Kevlar line to the mast and push pit.
Your comment on the water is what I dont understand. You use the surface to bounce out your signal. Never had a problem talking from Gibraltar to Southbound II in Ontario.

ka4wja · 20-12-2020, 12:38

Dominic,
Welcome aboard Cruiser's Forum!

EDIT:
Please let us know where you are located, where you are planning on sailing, what your primary use of long-range comms are, and what other equipment / systems you have on-board, etc....
Oh, and what type / size / brand boat you sail!!
ALL of that is important for us to know, in order to better answer your questions...

Right up front, yes please connect your M-802 directly to your main (house) battery bank, using as short of a run of power wire as possible....Not thru your distribution panel / breaker panel!

If you need to use a length greater than about 4' - 5', please use a larger size wire (larger than Icom supplies) for that run, using only the last foot or so, of the Icom-supplied power cable, for connection to the M-802's main unit.
FYI, most find 6 ga to be adequate to maintain 3% or less voltage drop on the 30-amp load of the M-802....but that is going to depend on the length needed for your install on your boat...

{Icom supplies the same length of wire for all the radios, but remember that this is based on being supplied with a regulated 13.6vdc, not our typical "cruising boat battery voltages", where reducing the voltage drop is a bit more critical}

FYI, this is for multiple reasons.....to maintain as high of voltage to the radio as possible....to reduce "transmit RFI" (reduce the possibility of your M-802 causing interference to other systems/devices on-board)....and reduce receive RFI / keep as "clean" (RFI-free) DC power to the radio as possible....as well as reduce blinking/dimming of lights on-board, and/or glitches in dc power supplied to sensitive electronics on-board...

Further FYI, the "crystal oven" in the main unit draws about 90ma - 110ma (approx 1/10 of an amp...one-tenth of an amp), and in a 24 hour day, that is approx. 2.4 amp-hours....{I figure 2.5 A/H, per day, from the M-802, even when turned off}
If this is too much energy for you to supply, then you may find a disconnect switch to be something to consider?
Please understand that if doing this, you are defeating a feature of a nice commercial marine HF radio (its high-quality, perfect frequency stability), until the radio has been turn on for 10 - 20 minutes....so, I really don't recommend this...
Solar power supplies what I need....and solar does it for most cruisers...
{FYI, when leaving the boat for weeks at a time, I do unplug the DC power cable on the rear of my M-802 Main Unit.....but that is more for lightning paranoia than for saving 2.5 A/H's per day....when leaving over-night, etc., I don't bother....and I do not know of any other sailors that bother, either!}
Should you decide to add a DC power disconnect switch (not really needed) I do NOT recommend a "remote control" / relay for this....one more thing to possibly go wrong, as well as the relay coil (when the radio is being supplied with power) will be drawing as much or more power than the radio does (when turned off), so you gain maybe one A/H per day? Not to mention, you've now added more voltage loss to the system (the relay contacts), and is this a "sealed relay", or will there be salt air corroding the contacts? You see what I mean....this is just not a good idea...

Now that I answered your question, may I offer you some learned advice?

1) First off, if you take the time to learn a few things first (before you install the radio, antenna, etc.), you'll love the M-802 and HF comms...
And, fyi, just about all you'll need to know about installing and using the radio, antenna, antenna tuner, and antenna ground, etc. are right here in the stickies (at the top of the Cruiser's Forum Marine Electronics page) and the links therein....so..

So, in that vein...Stop...

Don't move forward until you've read over some important things (see links) and understand a few basics....
This WILL save you time, effort, frustration, and money!

HF-SSB Radio, Proper Installation Tips/Techniques, etc.
https://www.cruisersforum.com/forums...tc-198305.html

Marine SSB Stuff (how-to better use / properly-install SSB, & troubleshoot RFI, etc.)
https://www.cruisersforum.com/forums...tc-133496.html

No, you don't need to read ALL of this....but at least read the first few posts....

And, watch some videos too...

Icom M-802 Instruction Videos
https://www.youtube.com/playlist?lis...rC-8QKVyMb4tVr

Maritime HF comms
https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y

HF-DSC Comms
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX

Offshore Wearther
https://www.youtube.com/playlist?lis...zdjTJjHlChruyY

I know some of these videos might be confusing before you've got the radio installed and hooked-up....so, you can fast-forward through some of it...

2) Understand that much of the M-802 manual is....well, it is a pretty awful manual!

Ask any of my fellow experienced engineers / HF radio ops / installers.....they will probably say "that manual is crap!"

Please follow the detailed recommendations that I post above, in the stickies, etc....and that published by Sailmail in the Sailmail Primer (links in the stickies)....and, do NOT follow the installation recommendations in the M-802 manual....
I'm sorry if that sounds harsh (and maybe arrogant?)....not my intention....
But, please read those stickies, and you will see what we are talking about!

3) Please use some other counterpoise, rather than the KISS....
Anything will work better....see stickies and other discussions here and on the SSCA disc boards, for a LOT of factual (actual, real numbers, scientifically-measured....as well as real-world, on-air testing) info....

If you have a bronze underwater thru-hull within 8' - 10' (closer is better) of where you'll be installing the remote tuner (AT-140), simply run a 3" wide copper strap from tuner to thru-hull (follow details in stickies, etc.) and you'll be MUCH better off!!

Or, you can use some strapping to a keel bolt....your pushpit, lifelines, pullpit, rub rail, etc....and you're still better off than the KISS...

Or, in a pinch, use any metal tanks, etc....and, you'd still be better off than the KISS....

Or, FYI....you can make your own KISS for free!!! (or at most for $5)....
See stickies and other discussions here and at SSCA boards, for details....
But take 3 pieces of wire, of some random lengths between 15' and 35', crimp one end of these 3 wires to a ring terminal and attach that to your AT-140 ground terminal, and toss the wires into your lazarette / bilge / etc....and spread them out a little bit (or not), and you'll still be better off than the KISS!!! Absolutely true....have a look at the test results!

But, fyi....
Please understand that with "antenna grounds" (like the antenna itself), just about anything metallic will work to some extent, it's just all a matter of degree / how good vs. how bad....
Heck, even no "antenna ground" at all will work!

SO>>>

So, don't overthink it...
The KISS is snake oil....nothing new there!

Quote:

Originally Posted by greenschooner

Hi folks,
i am about to install my used ICOM M802 on my wooden schooner.
Regarding the ground I decided to use the KISS SSB counterpoise.
I keep you updated on that one.
Looking thru the installation guideline from ICOM they say you should connect
the transceiver directly to the battery thru the supplied cable including the fuse.
On the other hand they say you should disconnect the the M802 from the battery when at anchor
so the transceiver can not drain the battery due to the “high-stability oven-heater type crystal oscillator”.
Thinking about that I plan to use a remote battery switch (or relais )which can be switched remotely from the switch panel at the nav station.
Anybody have any experience with that?
One of topmast shrouds will serve as a “backstay antenna” as we do have running backstays (45’ isolated).
On the plus side I think with the antenna more upright as a backstay it should transmit less energy into the water.

Merry Christmas and a happy new year, stay safe!

Dominic

4) As for "One of topmast shrouds will serve as a 'backstay antenna' ", that sounds fine....but...
But, can you describe this a bit more....I'm assuming this is just one of the main mast shrouds? (and, I'm not familiar with the term "topmast"?)
If so....that's fine...

But, fyi....there is no need to worry about the antenna being "more vertical", nor less vertical!

(a "Marconi-type" HF "vertical", is nothing like the VHF antenna....and it does not radiate the same....lots of intricacies / technical details here, that I won't overload you with....LOL)

Actually, having our "verticals" angled 15 to 20 degrees from vertical IS very advantageous for us "cruising sailors"!!
Here again, lots of intricacies / technical details here...but, suffice to say that moving the vertical just 15-20 degrees off of vertical, reduces the overhead null significantly (improving "regional" comms of 100 - 500 miles), but does NOT really effect the low angles of radiation for long distance comms (2000 - 10,000 miles) !

So, no worries there...

5) Also, in the stickies are the Clipping Issues and Speech Compressor discussion....be sure to read them!!!

Please read over the M-802 Clipping Issue posts / discussion here, and verify your M-802's serial number, of you may find yourself being frustrated by poor performance / intermittents that are easily solved by a free Icom Service mod/upgrade!

Also, be sure to verify your M-802's internal DSP-based Speech Compressor is turned ON (and leave it ON), otherwise you'll be frustrated by medicore transmit performance....please read over the M-802's Speech Compressor posts / discussions here, as well...

Dominic, there is a lot to learn here....and please don't think you need to know it all, nor that you need to learn it all at once! (I've been doing this for about 50 years....assisted in my first marine HF-SSB install in 1973, as an adolescent....and have been studying HF radiowave propagation and antenna system design since 1971....and teaching it since 1975, or so....)

So, just go one step at a time....
Read over some things here (and on SSCA and OCC boards), and watch the videos, etc....
And, please remember that just like navigation, sail trim, anchoring, head repair, line handling, etc. etc....HF radio communications / radiowave propagation / HF radio system installation / etc. are all somethings we learn, as we are not born with this knowledge!

So, take your time and learn this stuff, and you'll be good-to-go!!

Fair winds.

John

caffel · 21-12-2020, 12:47

This model is so popular that two books have been written for users like yourself:

https://www.amazon.com/Icom-IC-M802-...s=books&sr=1-1

https://www.amazon.com/ICOM-M802-Rad.../dp/0971564043

These are inexpensive compared to the many choices that you face in both installation and operation.
Cheers,
KC3LZR