do I really need 13.8 volts for Icom M802 SSB radio ?

[ohgary]

There are "battery Boosters" For example https://www.dxengineering.com/parts/mfj-4416c and they will make the radio happy. YOu will use a bit more batter of your battery up to do it but it can be done.

[ericoh88]

Originally Posted by Cpt Pat

I also found my Tiller Pilot A/P stopped misbehaving after I switched it to the lithium for power. I'd been blaming the HF transceiver, when in fact the problem was caused by voltage sag while transmitting.

This is a good one . Thanks

[svlamorocha]

Originally Posted by roverhi

Thought one of the design features of the 802 over ham radios is that they worked on low voltages where Ham radios might notl. The ham radios are supposed to output fewer watts as the battery voltage drops. Can't say that I ever noticed it as I've always been able to get through even with voltage at 12 + or - with my ICOM 718 ham radio. So no, you should be fine on the radio at 12.7v or whatever resting voltage is on your battery and even get out with voltages at 12v or below though mabe with not as strong a signal.

I don't know about your 718, but my 718 is very sensitive to voltage. I ran a controlled test with an adjustable power supply and found that when voltage drops below 13.5V or so volts power output declines more or less linearly with voltage. Granted, it is difficult to tell the difference when you are transmitting voice, but when use digimodes that transmut flat out the impact is clearly measurable.

[svlamorocha]

Originally Posted by svlamorocha

I don't know about your 718, but my 718 is very sensitive to voltage. I ran a controlled test with an adjustable power supply and found that when voltage drops below 13.5V or so volts power output declines more or less linearly with voltage. Granted, it is difficult to tell the difference when you are transmitting voice, but when use digimodes that transmut flat out the impact is clearly measurable.

I should add that I ran a similar test with an 802 and did not find a measurable impact of voltage on output power using digimodes.

[ka4wja]

cge,
1) Well, of course, the short answer is: No
No...you do not "really need 13.8 volts for Icom M802 SSB radio"...
And, that has already been posted...

Originally Posted by cgebluewater

I was reading the installation instructions for the Icom M802 SSB radio. It says to connect DC power wires to a "stable 13.8 volt supply".

2) The most accurate answer is:
The M-802 needs to have 13.6V +/- 15% (as ronstory wrote in post #4)....this is roughly from 11.6vdc to 15.6vdc...
But..

But, understand that this is at the dc power connector at the back of the radio, while transmitting (at full power), not at your DC panel, nor under receive-only....and this is for the radio to meet its full FCC Part 80 (maritime) specs...
Also, please understand that most breaker panels / distribution panels / etc. are not designed to handle these current loads without significant voltage drop, and that the direct connection to the battery bank is not only important for this, but also to reduce/eliminate DC power system RFI pickup/radiation...

Of course on-board our boats, at "battery voltages", this necessitates using adequate DC power wiring size....and this means if you need to use a length longer than a few feet, you will need to use a larger wire than what Icom supplies...for most mid-sized cruising boat installs, this is typically 6ga wire, but sometimes larger....remember you should keep the voltage drop to less than 3%, at max current draw of the radio, which is 28 to 29 amps (measured), 30 amps (spec'd)...

(FYI, this is all well described in these stickies which are above, right at the top of the Marine Electronics page...)
http://www.cruisersforum.com/forums/...tc-198305.html

http://www.cruisersforum.com/forums/...tc-133496.html


Further, you will find the M-802, and most marine HF radios (as opposed to ham HF radios) will perform as spec'd down to these lower voltages, and even operate (at reduced performance) at lower voltages....where as most ham HF radios will perform poorly at voltages below 13.0vdc, and most will perform very bad at voltages below 12.6vdc, and most will shut-down or be totally useless on transmit at voltages below 12.3 to 12.5vdc...where as actual marine HF radios will still perform up-to spec, all the way down to 11.5vdc....




3) You do not need a DC-DC voltage booster for a marine HF transceiver (M-802, etc.)....
And, assuming you have this connected directly to your battery bank (with adequate sized wiring), you should have no problems...

Originally Posted by cgebluewater

Ours has a pretty clean connection isolated from the rest of the DC power distribution panel. It is properly fused and circuit breaker/switched. But I assume like ours, most SSB radios installed on boats do not have a DC to DC voltage buster to increase the voltage from the typical 12.50 to 13.0 volts from the batteries up to the stable 13.8 that Icom recommends. So any thoughts as to how important it is to try and increase the voltage and if so what is on the market to achieve that ?

If you read the stickies posted right at the top of the Marine Electronics page, you see all the details...
http://www.cruisersforum.com/forums/...tc-133496.html

http://www.cruisersforum.com/forums/...tc-198305.html



FYI...like many Icom and other manufacturers' manuals, much is poorly translated....and some is just copied-n'pasted from some other manuals....not anywhere close to be easy-to-understand, and in some areas, even totally inaccurate!! (ex. their "defaults" in HF-DSC comms are as I show in the videos, not what is written in the manual!)


4) cgebluewater, Toys_with-time, et al,
The answers in how-to install and operate your M-802 are right here for you...and it's all free!!

Originally Posted by Toys_with_time

While we are on the topic of the M802, I finally finished the installation of my 802 and Pactor modem (only took me 7 years!) and then went to the ICOM manual to learn how to operate it and found the manual is next to useless. Anyone got any links or suggestions for a Dummies guide to operating the 802 and / or Pactor.

TwT

a) There are plenty of easy-to-understand videos that show step-by-step how-to use each button / feature of the M-802, as well as Maritime HF Comms in general, HF-DSC Comms, Offshore Weather reception, VHF-DSC, etc. etc...

Please have a look at these Youtube Playlists (and watch the videos in order in these playlists, as the videos are arranged in a logical order to best explain to laypersons how-to best use/operate the radio and all its features)....if you find some info to be repetitious, you can watch 'em in "double-speed" mode, or fast-forward...or skip to the next video, but please do try to watch the videos in the playlists, in order...

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


Maritime HF Comms (in general)
https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y


HF-DSC Comms
https://www.youtube.com/playlist?list=PLnN6ygtZ3h2n3z5nlv-ga2zYuPozhUXZX
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX


Offshore Weather
https://www.youtube.com/playlist?list=PLnN6ygtZ3h2mPZAx2vWzdjTJjHlChruyY


VHF-DSC Comms
https://www.youtube.com/playlist?lis...J6QugtO2epizxF


Please note that these videos are all produced LIVE, showing as-it-happens demonstrations / examples, of the M-802 (and all its features/buttons), and maritime HF communications, HF-DSC, offshore weather, etc...all LIVE on a real offshore cruising boat (while tied to a dock, in Florida)....I had no script nor director, it was just me / my camera / my radios, all extemporaneous....so...
So, there might be some repetition and abrupt edits, but they're free...so, please be kind...
{fyi, as long as it's just for your own private use, you can of course, download these and store 'em on your computer to watch 'em as needed, when away from good internet access....}




b) Also, as mentioned above, there are the stickies right at the top of the Marine Electronics page, and all the links in those stickies....
http://www.cruisersforum.com/forums/...tc-198305.html


http://www.cruisersforum.com/forums/...tc-133496.html



c) And, of course the Sailmail Primer has been the standard now for 15 - 20 years (and is of course linked to, in the above stickies, but here's the direct link here, as well...)
https://sailmail.com/wp-content/uplo...2/smprimer.htm




I feel confident that this will help??

fair winds..

John


P.S. Here are some "fun" videos, showing Offshore Sailing
https://www.youtube.com/playlist?lis...KgTCj15iyl6qoY


P.P.S. Just curious....Are the stickies above not showing up for everyone??
'Cuz, these questions keep coming up...and all this info has been right there now for 4 years...and some of my videos have been here for 5 years...

[NirvanaBob]

RE: Operating the M802 SSB radio. Totally agree re Operating Manual. It’s all there, but only becomes obvious AFTER mastering the various functions.
The good news is that a very competent radio chap who is a cruiser (Terry Parks, CDR, USN Ret.) got fed up with the manual and has wriiten “ICOM IC-M802 Made Simple For Cruisers”, which is very much better and will answer all of your question re operation and use of the radio, including how to unlock so if you are a Ham you can use the full spectrum of both marine HF and Ham bands.
Google Terry Sparks (resides in Oak Harbor, WA) and you should find a link for purchasing this and other of his books on Communications

[svmobert]

Originally Posted by Toys_with_time

While we are on the topic of the M802, I finally finished the installation of my 802 and Pactor modem (only took me 7 years!) and then went to the ICOM manual to learn how to operate it and found the manual is next to useless. Anyone got any links or suggestions for a Dummies guide to operating the 802 and / or Pactor.

TwT

Here is a good book for learning how to install AND use an M802 SSB. Terry Sparks ICOM IC-M802: Starting From Scratch - https://www.sea-tech.com/product/ico...-from-scratch/

[svmobert]

At a high level, it's not so much the battery bank voltage, but the voltage drop during transmission that is the issue. This is why we always recommend wiring the SSB power directly to the battery bank, not through an electrical panel, and using the included wiring harness from Icom is fine as long as you stay within the provided length. As soon as you have to go longer, you need to upsize the wiring harness based on the length of the run.

Most of the SSB installs I know of do NOT have the voltage boosters and work just fine, as long as they are installed properly.. (ie: proper wire size, length, and directly to the battery bank).

[ka4wja]

Not to beat a dead horse....
--- But, the Sailmail Primer (regularly updated) has been the defacto standard guide for marine HF radio installs now for almost 20 years....and it is free...
--- There are also many postings here and on the SSCA and OCC boards, from myself, Scott, Bill, Ross, Eric, etc., over the past 15 - 20 years, highlighting proper install procedures / techniques...
--- Every reputable Icom HF marine dealer selling the M-802, etc. also provides guidelines / procedures for installing the radio/tuner/etc...(they had to, 'cuz the Icom M-802 manual is so bad!)
--- Over the past 5 years, there have been free Youtube videos that take even untrained laypersons, step-by-step thru how best to use their radios...

So, if you've exhausted all of those....then have a look at Terry's book....it is a good guide, but in my opinion (based on my ~ 45 yrs of marine and ham HF experience, in installation and operation), the Sailmail Primer (written by Jim Corenman, who founded and developed Sailmail and wrote the Airmail program) is still the basis for everything else....

And, then there are the many postings (including the stickies right here and on the SSCA boards)...and for those that want to watch rather than read, there are the videos!!


~~~~~~~

Sorry to be contrary....but..
Richard, I have to politely disagree with you here on one point...

Originally Posted by svmobert

<snip>.. using the included wiring harness from Icom is fine as long as you stay within the provided length. As soon as you have to go longer, you need to upsize the wiring harness based on the length of the run.

For a 12vdc circuit, at 30 amps....a 10' (one-way) run of wire, the voltage drop from just the wire is:

12ga = .979 volts
10ga = .616 volts
8ga = .387 volts
6ga = .244 volts

Of course, double the length and you double the voltage drop...

So, if you use too small of a wire, and if your batteries are already at 12.2 to 12.4 volts....then you add in the voltage drop of the fuse / breaker inline between your radio and the house bank, and then the voltage drop in the wiring....and you're left with a fairly marginal voltage...

{I think Icom supplies 10ga or 12ga wire??? It looks big, because of the extra thick insulation, but think it's 12ga??}

Of course the M-802 and other marine HF radios will work up to the full spec's at voltages as low as 11.5vdc, and still work at reduced spec / reduced performance at even lower voltages....other than cost of the wire (and the labor of the guy doing the install) there is no good reason not to use adequate sized wire for the job!

Yes, the supplied wires will "work"....but this is not optimal, and not recommended to be used by any experienced marine radio installer, if the radio will be mostly operated at "battery voltages"...

Voltage Drop Calculator

https://www.westmarine.com/WestAdvis...e-And-Ampacity

https://www.bluesea.com/support/arti...r_a_DC_Circuit


I'm not saying that Richard is wrong....just that I disagree with him here....I don't believe in using too small of wire, just 'cuz it "works", rather I strive to recommend what is "best" for the most reliable operation...


{fyi, in full disclosure....everyone here knows I'm a radio nut....so, it won't come as a surprise to some that I use a 4' - 5' length of 2/0 wire from my house bank to a terminal, then a 4' length of 2ga wire to the terminal next to the radio, and a 1' length of the Icom supplied power wire....yes, I understand that these terminals do introduce some possible failure points, but if done correctly will out-live me....and no issues in > 14 years in my current set-up...and have a measured voltage drop of about 0.12vdc at full 150 watts out in FSK carrier!!}


fair winds...

John