Turning an Icom 718 into a marine SSB

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jim99

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I was today offered an Icom IC-718 for pretty cheap.

A friend bought the ham radio from another friend, but decided not to install it.

I'm told it had a diode or something clipped to open it to marine bands.

So my friend, who might not really be the most knowledgeable about hams or marine SSBs though believes he is, figures if I install a crystal stability thingie and a DC to DC power converter to maintain a 13.8-volt power supply, I will have a rig that is performance-wise indistinguishable from a marine SSB.

Is he right?
 
Google says that Icom did make an SSB version of the 718, so it is not impossible that a simple mod, not dissimilar to the MARS CAP mod, would allow it to be used as an SSB, but you can be sure that it would not be compliant with SSB licensing & certification requirements.
 
I modified mine years ago it was a simple diode removal job, I can't remember which but there is bound to be information on the net, just not the HAM forums. I doubt that it would be CE compliant. No one will ever check though unless you start transmitting in the marina and are causing problems when you just might get a visit from whoever does the tracking and enforcement nowadays.
 
A ham radio is already SSB, but I think you meant Marine SSB.
This Icom radio could easily be used for Marine bands if it's been "opened up" (normally has transmitter disabled for non-Ham frequencies.) But there will still be a number of differences between it and one designed for marine use.
Marine bands are normally channelized, whereas ham radios are not. This means you'd need to tune exactly onto the channel frequencies. Easily done and more a part of your operating technique that some special procedure.
Marine radios are normally better protected for the sea air environment. Corrosion could be an issue.
Marine radios are 125W output max, whereas most Ham sets are 100W.

Of these, only the corrosion might be an issue. I've operated a Yaesu FT857 (ham) on my boat for 6 years. I take it out in winter. It hasn't corroded yet, and I have a look each year.
 
Yes the 718 can be modified to operate on marine bands but you need a little bit of knowledge to do it and not cause problems for others. Also beware of using it on Winlink or Pactor at anything over 30% power or you will say goodbye to the output.

Three diodes to remove.....I think it is D 53....54....And 55.

Your set will Not be channelised!

See here for manual☺
http://www.icomamerica.com/en/downloads/default.aspx?Category=40
 
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jim99 said:
So my friend, who might not really be the most knowledgeable about hams or marine SSBs though believes he is, figures if I install a crystal stability thingie and a DC to DC power converter to maintain a 13.8-volt power supply, I will have a rig that is performance-wise indistinguishable from a marine SSB.

Is he right?
Click to expand...

Probably wrong if tested on the bench against marine ssb spec, quite possibly right in the real world with someone who knows what they're doing operating it.

But would you want to? If in Europe then marine ssb traffic must be minimal, plus the LRC license ain't cheap, your cheap deal might not be quite as good with that thrown in. And hams won't talk to you if you don't have a call sign, you'll be sussed in a moment.

Why not go HAM - you'll need an advanced license to transmit from a boat, a local ham club would get you through that and you'll learn lots, enough to not make a mess in the airways transmitting on either bands.

Onboard i (very occasionally in Europe) use a IC7000 straight onto the batteries, works fine and occasionally useful to get gribs away from web acccess with winlink and once in a while have a chat with some hams or play on the digital modes like PSK31.
 
Thanks for the replies. Lots of information to consider and things to educate myself about.

Always thought I would get my ham license, just figured it would be nice to be able to access marine bands. Another friend is sending me links to ICOM M710's for sale and figures this is the best, cheapest way to get into ham and marine ssb.

The 718 is already opened up apparently, but I have been told that ham rigs can get messy in the marine bands, due to not having tolerance for low battery voltage (best used with a voltage booster or your engine running) and lacking channel stability. And, no, I don't know what I am talking about.

Maybe I should just buy the radio and get a ham license and figure things out from there.
 
Operating on low battery voltage:
This is usually more an issue of volt "sag" when transmitting on higher power (100W ham, 125W marine radios), where on peaks of voice cause peaks of output power which in turn draws peaks of current off the battery. If that battery is relatively small (say 40-60Ah), the output voltage will sag, and low voltage causes distorted transmit audio. The answer is to either reduce output power, or get a bigger supply. The easiest way to get a temporary bigger supply is to idle the engine provided your alternator has a good output at those revs.

Channel stability
Channelised radio is a bit like modern car radios where you select the station by selecting a preset frequency listed by station name rather than frequency. In marine radio this helps to ensure that there's enough space between adjacent stations, as the channels are automatically set far enough apart. It also means that each station doesn't need to "tune" the other in. In Ham radio is free for all. No channelization, so you select a clear frequency and go ahead. But that frequency you select might be a pre-agreed one, and that's almost the same as channelization. Using a ha radio on marine bands, you just look up the frequency of the channel desired and dial it up. Not really so different to looking up say Radio 4 at 198kHz, and setting a receiver to that. You just set the set to a desired frequency. That others got there by selecting a channel is of no consequence.
Stability in this context is about the sets possible drift in frequency. Modern ham and marine transceivers don't have much of this problem. It's rare. And its doubtful that there's a difference between the generic types "ham" and "Marine" in this area.

But to see the worth of marine SSB in the vicinity of the UK, get a hold of any SSB capable receiver and have a tune around. You'll hear very little. If you know where to look, you'll hear a few marine forecasts by some European coastguard (or equivalent) organisations, but little if any actual traffic. The only real exception is fishing trawlers, easily identifiable by their lack of identification and the quality of their language. Some know only a few words, a high percentage of which start with F. All of that spoken with very strong regional accents, often completely unintelligible by others.
 
A few points I would suggest considering:

1) Don't only look at "HF"—there is a (relatively) popular amateur band at 160m or about 1800kHz, so this set will probably be able to go that far at least. I have only done the SRC, but I recall a distress frequency at 2182kHz being mentioned—you would probably be able to access this but maybe worth looking at the set's specifications, as it is possible you may be in the "roll-off" of the low-pass filters for 1.8MHz. Probably not, as there is another amateur band at 3500kHz, and filters are usually designed to cut out the "third harmonic"—i.e. 3x the transmit frequency, which for various reasons is often generated by transmitters, but worth checking—otherwise your filters could be damaged and the output power won't be as much as it ought to be. Sub ~3000kHz is technically classed as "MF".

2) Think about antennas: radio amateurs usually use resonant antennas, often a vertical wire 1/4 of the wavelength long. This is not usually practical for amateurs on land above 80m, and on a yacht I don't think one could reasonably go much beyond 40m wavelength--i.e. a 10m antenna. On land, a fibreglass fishing pole or similar is commonly used; I have been giving some thought as to how this might be adapted to yachts, and I suspect it would be awkward but could probably be guyed to the mast using the topping lift and an intermediate set of guys to the taffrail—but would be a tremendous faff to set up and obviously not feasible if the reason for your distress is bad weather...
Alternatively could hoist the top of the antenna wire on the topping lift, but then issues arise with getting too close to a (metal) mast—the antenna will no longer be tuned and the radiation pattern will become somewhat directional—but not in an easy to predict way...may have to run some simulations!
The most common approach by MF/HF users on a yacht seems to be an isolated backstay—this is then driven via an "antenna tuning unit". The need for this arises due to the length of the antenna not matching the frequency appropriately—some of the power is reflected back from the end of the antenna instead of being radiated as a radio wave. If you let this come back into your transmitter directly, and it is more than the rating of the transmitter, one of two things will happen: if you're lucky (highly likely on a modern set) it will reduce power and then refuse to transmit entirely until you've improved the antenna; if you're unlucky it will blow up the transistors in the output stage, requiring replacement. The antenna tuning unit effectively absorbs this reflected power—it doesn't make your antenna more efficient, as it won't ever be anything like as good as a resonant antenna—but it protects your transmitter. Food for thought... a manual ATU for 1-200W is probably cheap to come by but will require some adjustment each time you change frequency.

3) Just for clarity, SSB is "single sideband"—properly, "single sideband suppressed carrier", and is only one of the potential ways of transmitting voice over this radio set. You may have noticed the other buttons/settings on the fascia of the radio, which will probably include AM, FM, and maybe "RTTY" (radio teletype) or something along those lines—a popular way of sending data via amateur HF radio. It's really an HF/MF transceiver rather than an SSB set, though please excuse my pedantry...

4) Definitely worth doing amateur radio exams; the first two involve only sub-A level physics and some specifically radio related stuff (all in the textbooks for the course, available from radio clubs or the RSGB direct) and the last one is not too bad if you read up on it diligently—if you have a maths/science related background it will probably not pose too much of a difficulty. The pass mark for the latter exam is only 60%, too... They will give you an increasing appreciation for the complexity of radio systems and also a vague idea of how these sets work.

Sorry for such a long answer! Happy to answer questions if I can...
 
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weustace said:
4) Definitely worth doing amateur radio exams; the first two involve only sub-A level physics and some specifically radio related stuff (all in the textbooks for the course, available from radio clubs or the RSGB direct) and the last one is not too bad if you read up on it diligently—if you have a maths/science related background it will probably not pose too much of a difficulty. The pass mark for the latter exam is only 60%, too... They will give you an increasing appreciation for the complexity of radio systems and also a vague idea of how these sets work.
Click to expand...

I agree. The Foundation and Intermediate are no problem - the Intermediate does require a practical test, though.
Also, to operate from a boat you need to progress to a Full Licence.
 
While the backstay antenna systems (I use this) is often not the ideal length, and for the lower frequencies way too short, the performance is still adequate.
My Yaesu FT857 with auto ATU will tune most frequencies from the 1.8MHz band through to 50MHz band. It does well in all amateur bands, but there are a few marine frequencies (channels they call them) that it won't tune being just the wrong length.
Even though that a antenna is very short for the 1.8MHz (160m) band, the whole arrangement being over salt water gets out surprisingly well, with no problem being heard in near Europe from the west coast of Scotland. On 14MHz, no problem to USA most days. (poor propagation excepted). It can be fun speaking to boats in the Baltic or elsewhere like that on 7MHz band.
 
Interesting to hear that–I had always assumed the VSWR on those antennas would be too big for an internal tuner–if it isn't this simplifies the OP's problem!
 
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