Questions on SSB installation

[Pizzazz]

I got my hands on an older SEA 235 radio and tuner and I am planning a new install on my Hunter 31. The 1984 Hunter 31 has an iron kill, stainless keel bolts, split backstay that attaches to chainplates molded in the fibregless. A couple of odd questions:

1) I would like to use the backstay and one of the lower split legs as my SSB antenna. The tuner connection will be from inside the locker directly to the throughdeck bolts. I will use an insulator at the top of the mast. The total length of the antenna is around 44 feet. Is this a good length or should I try to stay closer to the recommended 23 feet (meaning to put the insulator lower than the mast top)? Is there any issue with the insulator being so close to the top of the mast, i.e. is there some stand off distance that is recommended or it does not matter?

2) The backstay is split via a small triangular looking stainless steel plate. Would it make sense to replace that plate with a thick piece of starboard (or any other strong insulating material, suggestions please)? Then I can connect the upper backstay to one of the lower legs with a conducting plate but leave the other leg insulated. The alternative is to put an insulator in one of the backstay legs but it does not look pretty or symmetrical. Note that the backstay on the B&R rig is there for decoration only, it is not really load bearing or needed.

3) For the ground connection, everyone is recommending a copper stripe. I can't find one easily. Could I just use household aluminium foil, folded and strengthened with duct tape? I understand its conductivity is 60% that of copper but this should not be such a big issue if the foil is wide enough. Any issues with corrosion I should be aware of where the foil will connect to the ss keel bolts?

4) Should I also connect the radar RF ground to the keel or it would not matter? Do I connect just the SSB tuner to the RF ground or the transceiver as well?

5) The SEA 235 has a number of ports at the back to connect to a seabus controller, a serial port and a parallel port. I imagine that if it is connected to a laptop via the serial interface and the audio to the soundcard, with the right software, it will be able to do Winmor and all sorts of digital wonders without the need of the SEA specific controller. Any software recommendations? I understand that the easiest solution is to interface it with a Pactor II modem but I am looking more for a software based solution as I would not use it enough to justify the cost of a Pactor II modem.

Thank you,
Pizzazz

[ka4wja]

Pizzazz,
1) First off, there's no need to reinvent the wheel...this has all been done and discussed, a LOT!

Understand that it's not rocket science, and is all very predictable / reliable...



2) Secondly, please read over the "sticky" at the top of the Marine Electronics page....
http://www.cruisersforum.com/forums/...tc-133496.html

Be sure to follow all the tips/recommendations there, and in the Sailmail Primer...
SailMail Primer

And, also be sure to watch these videos....although they seem to be about "operating", they will also teach you a good deal about "installation"...

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

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

Offshore Weather, etc.
https://www.youtube.com/playlist?lis...zdjTJjHlChruyY



3) Third, are some specifics, in red...

Originally Posted by Pizzazz

I got my hands on an older SEA 235 radio and tuner and I am planning a new install on my Hunter 31. The 1984 Hunter 31 has an iron kill, stainless keel bolts, split backstay that attaches to chainplates molded in the fibregless. A couple of odd questions:

1) I would like to use the backstay and one of the lower split legs as my SSB antenna.
This is good.

The tuner connection will be from inside the locker directly to the throughdeck bolts.
I assume you're attaching the GTO-15 wire, from the tuner to the chainplate?
This is good.

I will use an insulator at the top of the mast. The total length of the antenna is around 44 feet. Is this a good length or should I try to stay closer to the recommended 23 feet (meaning to put the insulator lower than the mast top)?
Actually, 40' to 45' overall antenna length is considered "standard" and is recommended by most...(this includes the length of GTO-15 wire, as this IS part of your antenna)...
But, keeping the upper insulatort a few feet from the top of the mast is best...so, if you make it 40' - 45' overall, with the top insulator 2' to 3' from the top of the mast, you're good-to-go!!

Is there any issue with the insulator being so close to the top of the mast, i.e. is there some stand off distance that is recommended or it does not matter?
Although, you can place it right at the masthead, it is best if placed 2' to 3' from the masthead....



2) The backstay is split via a small triangular looking stainless steel plate. Would it make sense to replace that plate with a thick piece of starboard (or any other strong insulating material, suggestions please)?
Starboard is NOT a structural component and CANNOT be used as a rigging insulator!!!

Having said that, many who have split backstays over-think this...and as you described (fiberglass boat, with chainplates molded into the fiberglass), if you feed one chainplate and have only one upper insulator, you end up with the whole backstay (including the other leg of the split, going to the other chainplate) as your antenna....
Now, this is not really optimal, but it DOES work....although some have found RFI issues, this isn't necessarily a direct effect of having both legs of the split as part of the antenna..
This other leg being part of the antenna, also adds somewhat to the antenna length / effects its resonant freq....


Then I can connect the upper backstay to one of the lower legs with a conducting plate but leave the other leg insulated. The alternative is to put an insulator in one of the backstay legs but it does not look pretty or symmetrical.
Pretty??
Symetrical??
Not sure how to answer / comment on those things...
But, if you wish to eliminate the issue / anomaly, I describe above, you add the insulator to the upper end of the other split leg...(yes, this does add some cost, and you might not find it pretty....but is the optimal way of doing it...)


Note that the backstay on the B&R rig is there for decoration only, it is not really load bearing or needed.
Huh???
I spent all the time answering the above, and now I see that you don't have a backstay???
Then what is this wire that you are talking about???

If this wire is in fact, "decorative", then why not just run ONE SS wire from the "chainplate" to the masthead, with one insulator (a few feet of Sta-Set, is plenty of "insulator" for this set-up) at the top, feed this as an antenna, and you're good-to-go!???

BTW, this is what is called an "alternative backstay antenna", and has been discussed / recommended here (and elsewhere) for a couple decades....it works, it works well, and is pretty cheap!!



3) For the ground connection, everyone is recommending a copper stripe. I can't find one easily. Could I just use household aluminium foil, folded and strengthened with duct tape? I understand its conductivity is 60% that of copper but this should not be such a big issue if the foil is wide enough. Any issues with corrosion I should be aware of where the foil will connect to the ss keel bolts?
NO....
You cannot use aluminum foil!!

It appears you do not understand what the "copper strap ground connection" is for???
This is to give you a low-impedance RF ground connection to the sea water, and are using the sea water as your antenna ground / RF ground....
I (and others) have written about this for years / decades....it's all pretty straight forward, and is easly explained...

BTW, copper strapping is easily purchased just about anywhere in the 1st world / US / UK / EU, etc...
Sold as copper flashing in roofing supply companies, home depot, lowes, hardware stores....and in most RF parts houses and radio shops....and in many electrical supply houses as well...
BUT...
But, my favorite place is where it is not only cheap, but very high-quality, clean, smooth, nicely coiled and packaged....and this is Georgia Copper!
2' of 3" wide, 0.012" thick, is pretty cheap....about $59, and the 0.022" thick strap is $93 (but, the 0.022" thick strapping is pretty stiff to bend in tight places....the choice is yours)

Check out Georgia Copper...
GEORGIA COPPER - Copper ground strap
GEORGIA COPPER - Copper ground strap

GEORGIA COPPER - Comparison of Braid, Strap, Wire

Georgia Copper - Frequently Asked Questions

Except for the ends / where the connection is made, spray the strapping with some paint / epoxy / lacquer, and this will last decades!

{Also, use Penatrox-A, conductive grease, for any wet/moist grounding connections, etc...allowing them to stay clean, dry, and maintain excellent RF conductivity for years and years!!}




4) Should I also connect the radar RF ground to the keel or it would not matter?
NO....

Do I connect just the SSB tuner to the RF ground or the transceiver as well?
Just the tuner!!!



5) The SEA 235 has a number of ports at the back to connect to a seabus controller, a serial port and a parallel port. I imagine that if it is connected to a laptop via the serial interface and the audio to the soundcard, with the right software, it will be able to do Winmor and all sorts of digital wonders without the need of the SEA specific controller.
SEA made some nice radios, but you are going to spend a good deal of time and frustration trying to get this to do all of what you want it to do in a easy / efficient way...

First off, Winmor is only used on the ham radio bands, not marine freqs....so, you will need to not only program and tune the SEA 235 onto the ham bands (don't remember if the 235 will do this easily, like the SEA 222 does???), and you will also need to study up and get your ham license!!

Secondly, you will need some sort of connector, so why not just call SEA and get it from them, along with downloading the 235's manual, and asking them for their specific recommends??


Any software recommendations? I understand that the easiest solution is to interface it with a Pactor II modem but I am looking more for a software based solution as I would not use it enough to justify the cost of a Pactor II modem.
It seems you have decided that you require e-mail connectivity when at sea / on-passage, as this is the only thing that you'd need either Winmor or PACTOR for....
So, if this is the case, you have your answer....
There are two options for e-mail connectivity via HF radio:
--- WINLINK (via PACTOR II, or III, or Winmor)
--- Sailmail (via PACTOR II, III, or IV)

Now, please understand that having e-mail connectivity at sea / on-passage, is NOT necessary at all, for most offshore sailors / cruisers!!
The gold standard of offshore marine weather is available for free without any special modem, costly software, e-mail connectivity, etc.!!!
Offshore / Hi-Seas Weather data / forecasts

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


So, you must be looking at some business necessity here, and as such I need to remind you that you CANNOT use the ham radio bands / Winmor for any business use at all....and will recommend Sailmail (and unfortunately, a rather expensive PACTOR modem)

If this is not the case, in that you do not have a business-use / necessity for e-mail connectivity at sea / on-passage, please let us know what your e-mail at sea requirements are, and we can point you in the right direction...


Thank you,
Pizzazz

I hope the above helps....and remember that this has all been discussed many times over....and most of the answers to your questions are in the links / references in the "sticky" right up top!

Fair winds...

John

[ka4wja]

Pizzazz,


Typo correction to my post above!!
25' of 3" wide strapping is $59....(I left out the "5", so it looks like 2' is $59!)
Sorry about that!!!



Also, while typing the answers to your questions last night, I got a phone call and got distracted....and forgot to add some clarification about the "copper strap" and antenna grounds / RF grounds...

So, here it is...
When I wrote:

...the "copper strap ground connection" is....to give you a low-impedance RF ground connection to the sea water, and are using the sea water as your antenna ground / RF ground....
I (and others) have written about this for years / decades....it's all pretty straight forward, and is easily explained..

I failed to mention that this short run (< 8') of wide copper strapping is supposed to be connected to the sea water via an underwater grounding plate, or nearby bronze thru-hull...
Your mention of the iron keel and keel bolts, implies that you wish to use this as your underwater connection??

While this is do-able, making sure the length of copper strapping is as short as you can get it (location of the tuner may need to be considered as well), is what will allow this to work well...(usually we say < 8' in length...but lengths of 10' or so, still work fine....although shorter is always better!!)
And, with a 31' boat, it is likely that the aft keel bolt would be within 8' - 10' of your tuner location....so, this should be okay!



If you wish further info / clarification, please ask....and also be sure to read the above referenced links, and do a search here for more...


Fair winds..

John

[CSY Man]

I had a SEA 235 (R) on previous boat.
Had the split back stay. Top insulator close to the top of the mast.
Copper strip in a cockpit locker. Dyna plate under boat. The rig worked great.
Did several radio checks from Fort Lauderdale to Lima Radio (Peru)
Enjoyed listening to news from BBC while anchored in the Bahamas.
Great radio. If you are using a Pactor modem for email, you may want to instal a cooling fan.

[roverhi]

It is my understanding that the ground plane does not need to be connected to the water. It is not a ground as in the typical electrical terms.

[Reefmagnet]

Not to hijack the thread, but I'm replacing my 30 yo hf radio that had 60 watt max output with a newer model (icom 710, fwiw). The ground plane is a stud cast into the keel connected to the radio with what looks like welding cable. I was thinking of using some 1/2" diameter ductile copy plumbing pipe as a replacement, mainly because I have some on hand. Would this work, and if so could it be used as is or would it be better to flatten into a strap?

Sent from my SGP521 using Cruisers Sailing Forum mobile app

[ka4wja]

Roverhi,
I hope you don't mind a brief reply, 'cause I don't have the time to write a treatise on this again...
(and to my fellow RF engineers, my apologies for taking some short cuts in explanation)

Please remember that "everything" can work, to some extent....in antennas, antenna grounds, etc., it is all a matter of degree!
(heck, even no antenna ground / RF ground at all, works to some extent!)


The main purpose of an antenna ground / RF ground, is to allow the antenna currents (otherwise lost in / shunted to the ground) to be cycled-back to the feedpoint and radiated...

Originally Posted by roverhi

It is my understanding that the ground plane does not need to be connected to the water. It is not a ground as in the typical electrical terms.

Optimally, we'd like to have our antennas sitting over an infinite plane of silver-plated copper, that we use as our antenna ground / RF ground!
But, of course that's not possible....not at all!

So, what's the next best solution?
Other than a large 10-wavelength circle of copper, the sea water is our best solution!
Sea water has GREAT RF conductivity and works wonderfully as our HF antenna's ground!!
That is, IF you connect to it!

As has been proven in both countless real-world scientific tests and by the math, this direct sea water connection is best!



If you cannot do this, use of an artificial counterpoise, such as wire radial, lifelines, alum toerails, etc. is a good second choice...
And, they work well...



Other alternatives are: using large flat surfaces, such as metal tanks, ballast, etc. also have some use....but not as good as the ones above...
And, finally....use of these "alternatives" (such as metal tanks), and/or a copper strap, in close proximity to the water, to "capacitively couple" to the sea water....but, this is unfortunately the least effective of the alternatives (again, proven by real-world testing and the math), and whether these tanks, or strapping are close to the water or not, they work about the same (to some extent, but not so good)





Now, please do not confuse the extremely low pseudo-Brewster angle that HF signals have over sea water....as this effects the signals in the air, and does not effect the antenna system's efficiency!!


I hope this helps..

Fair winds.

John

[roverhi]

John, your short answer was about 50 times as long as my question. Hope you wife's not mad at me for you missing dinner. Just wanted people to know that they didn't have to have a bolt on keel or grounded to the water to get a good signal. With an encapsulated keel and nothing but through hulls in contact with the water, didn't have a good solid mass or square feet of copper mesh to hook to. Copper strips down each side of the hull below the deck works on current boat.