Active Capt / Defender SSB special

[ka4wja]

z,
Just noticed that I forgot to specifically point out another video, where I specifically describe / show the proper use of the RF Gain control...(and headphones, etc.)
Have a look at this video...
(specifically from 10m 54secs to 14m 20secs, for details of the RF Gain control, etc.)

https://www.youtube.com/watch?v=_OaHBpAfmbE

Fair winds..

John

[a64pilot]

Does this thing really work?
http://www.defender.com/product3.jsp...9059&id=332511
Gam split back stay antenna

If so I think it would be the way I go, but I'm a suspicious type, while I can see how you could make a perfectly tuned antenna, laying it right alongside of significant metal mass has to have a huge effect, maybe making it directional or blocking a lot of signal?
Seems if it worked it would be the most popular, or is it new?

Why copper strip for connecting to the thruhulls? Why isn't good wire as effective? Is copper mesh type of wire good, like old fashioned battery ground cables?

Is there a good book on installs?

Sent from my iPad Pro using Cruisers Sailing Forum

[ka4wja]

A64,
Waste of money...

Don't have the time right now...
More later...
Do a search here, you'll get the details...

John

[a64pilot]

Waste of money was all I needed, thanks


Sent from my iPad Pro using Cruisers Sailing Forum

[SV THIRD DAY]

Originally Posted by a64pilot

Is this a good package? What is is missing except the antenna of course

I would rather buy from www.sea-tech.com
He will match/beat any internet price BUT and here is the BIG But...he will be there to answer your service calls and questions. I love Defender but will the defender Tech walk you through your radio and how to install and use it? We both know the answer to that question in No, you will be directed to the Icom customer service center...good luck with that.

Steve over at SeaTech also knows what other things you want and NEED, like the mounting hardware and cabling that doesn't come with the "great deal kit". I don't have any relationship with Steve other than seeing him helping cruisers at the boat shows for years.

[SV THIRD DAY]

Originally Posted by a64pilot

Does this thing really work?
Gam Split Lead SSB Backstay Antenna
Gam split back stay antennam

While net controller and manager for the Southbound Net in Pacific Mexico for 4 years I have spoken to quite a few cruisers with the GAM antena, KISS ground, and M-802/AT-140 tuner combo and there radios were just as clear to me as the guys that insisted on a Dynoplate along with miles of copper in the bilge for a proper counterpoise.

Of course even saying such a thing is like saying your support ISIS and the attacks on my family heritage are sure to follow, but I'm just telling you what I've seen and more importantly heard first hand....time to duck and cover....

[ka4wja]

A64,
(most of this has been covered over and over again...have a look at the "stickies" and do a search...and you'll see that most of this info is there...)

1) I've posted about the GAM Split-lead antenna before, it is not new (and the basic premise of slant-fed, shunt-fed, "coupled antennas", date back to the 1920's / 1930's)...and while it does work, it doesn't work as well as other antennas (such as insulated backstay or "alternative backstay antenna") for our applications, and costs a LOT more than some other options...
And, understand that it is not a "tuned" antenna at all....it requires the same tuner and ground that any other end-fed / random-length antenna does...

Originally Posted by a64pilot

Does this thing really work?
Gam split back stay antenna

If so I think it would be the way I go, but I'm a suspicious type, while I can see how you could make a perfectly tuned antenna, laying it right alongside of significant metal mass has to have a huge effect, maybe making it directional or blocking a lot of signal?
Seems if it worked it would be the most popular, or is it new?

Here is more than you probably wish to know about the GAM Split-led antenna and slant-fed/shunt-fed/coupled antennas....

Here is what I wrote a while back....

Originally Posted by ka4wja

Finally, regarding the GAM Split-Lead antenna....
This is NOT a new idea, and is not snake oil...
But, that also does NOT mean that it is a good choice....

I don't have the time to write a treatise on this, but in brief...
"Coupled antennas", "shunt-fed antennas", "slant-fed antennas" (which is what the GAM on a backstay IS...), have been around for almost 100 years....and much commercial experience has been amassed from the 1930's thru 1960's, and much ham experience has been more recent (1950's thru recent years)....
And, the bottom line is, they are very difficult antennas for multiband/wideband operation (which is masked by our modern remote antenna tuners/couplers)....AND they can also induce transmit RFI into the structure and wiring attached (and into some systems on-board) that would not be the case with a direct, non-coupled, antenna....

So, while the GAM Split-lead antenna is not a "bad" antenna, it can be a less efficient antenna, and can be one that causes problems...
There are so many variables that it is impossible to determine ahead of time, whether one will work well for someone, versus another one not...
(if you look at the reports from users, they're almost all, either 100% positive or 100% negative....which is completely understandable, as this backs up the long-established science behind it....)

As for me and my recommendations go....I have always recommended against it....NOT because it doesn't work, but because we cannot know how well it will work up front (as we do with either the ubiquitous insulated backstay, or the very inexpensive "alternative backstay antenna", or even with a whip...), nor can we be certain about any potential RFI issues....
So, with an "alt backstay antenna" being so inexpensive, and a proven/known performer, anyone who wishes for a wideband HF antenna without using their backstay, should consider it before spending the $$$ on the GAM...
{BTW, I suppose you can guess that I have no issue cutting a stay and adding an insulator as desired....
But, for those that worry about rigging insulators breaking and causing a dismasting....in all my years of sailing, I've seen some dismastings and quite a few broken/damaged masts and rigging....but NEVER seen a broken rigging insulator, ever!! They are designed to be stronger than the wire size they are attached to....
But, for a "belt-'n-suspenders" approach, you can use Hydn Hi-Mod "fail safe" rigging insulators....if for some weird reason the insulator fails, the stay does NOT...
FYI, most rigging failures I've seen were almost always from lack of maintenance!!}



I hope this helps..

Fair winds...

John

And, here are some other discussions where the GAM is discussed...
http://www.cruisersforum.com/forums/...ml#post1777236

http://www.cruisersforum.com/forums/...ml#post1777138

http://www.cruisersforum.com/forums/...ml#post1844325

http://www.cruisersforum.com/forums/...ml#post1961303

http://www.cruisersforum.com/forums/...th-133336.html

http://www.cruisersforum.com/forums/...b-63811-3.html

http://www.cruisersforum.com/forums/...nna-10386.html




2) As for use of copper strapping to connect to the sea water ground....if you are using the sea water as your antenna ground / rf ground....you want a direct, low-inductance connection to the sea water....(note that this if completely different than using "radials" / artificial counterpoise, where the wire itself is your antenna ground / rf ground, and here simple round wire works perfectly....)
If you're using the sea water as your antenna ground / rf ground, then you need to connect to the sea water as best you can....if you have an underwater ground plate directly under the tuner, and can connect to it with a short (~1' or less) piece of wire, then wire will be fine (I'd recommend 8ga or larger).....but, once this length grows to what most sailboats allow (6' - 10'), the amount of inductance in round wire increases the RF losses in the ground system significantly....(we discussed this a few years ago on the SSCA boards, and I did the math there for everyone, and once you see the numbers you understand why copper strapping is recommended....and fyi, even 0000ga wire has much higher inductance than 3" wide copper strapping....and is a LOT more expensive....25' of THICK 3" wide copper strapping sells for about $50 retail, and less than that from roofing suppliers....so a few feet of strapping is a relatively cheap part of the installation!!!)

And, please do not try to use copper braid on-board!!!
This might work well for DC grounds (and even AC ground), but is a very bad choice for RF grounds....
The tiny wires making/breaking contact, as the uncovered braid moves/flexes can cause significant RFI issues on-board, as well as cause intermittents...and when the copper starts to corrode, things get even worse....yes, "tinned copper braid" won't corrode, but still has the other issues...

Sometimes I wonder why there is such a negative response from some when they read "copper strapping"....yes, it's a pain to install, but it's usually just a few feet...and if you use strapping that's at least 0.012" thick and/or paint it or epoxy it, it will last decades!!!
(what else on board costs about $50 and lasts decades?)

Further, in addition to the advice given here and on the SSCA boards, the Sailmail Primer details how-to effectively and efficiently install your Marine SSB radio....
Read it...Print it...Use it...

Originally Posted by a64pilot

Why copper strip for connecting to the thruhulls? Why isn't good wire as effective? Is copper mesh type of wire good, like old fashioned battery ground cables?

Is there a good book on installs?

If you look at the "sticky", right at the top of the Marine Electronics page, ALL of the links needed to find ALL of this information are right there!!! Have a look....
http://www.cruisersforum.com/forums/...tc-133496.html

As I said earlier, there is a LOT more to all of this....and this is why I put ALL of this down in a reference for you all...it is all right there in the "sticky"...



I hope this helps...

Fair winds..

John

[colemj]

Originally Posted by SV THIRD DAY

While net controller and manager for the Southbound Net in Pacific Mexico for 4 years I have spoken to quite a few cruisers with the GAM antena, KISS ground, and M-802/AT-140 tuner combo and there radios were just as clear to me as the guys that insisted on a Dynoplate along with miles of copper in the bilge for a proper counterpoise.

I don't have any experience with the GAM or KISS and can't pass any judgement.

However, pretty much all of the numerous nets I have experience with are mostly line-of-sight or ground wave at most (and could probably be done with VHF if more people could manage a decent install of those). And everyone is usually at high power.

The net traffic hits our attenuation circuit so hard that the radio is deaf for the first few seconds after trying to come back from it.

I'm always amazed at all the people requesting signal reports on 8MHz using 150W, and being happy to hear their radio is "loud and clear", when they are located 15nm away from the net controller.

So I wouldn't use local net traffic as a guide to system performance unless you are on something like the MMSN that you can get replies from much further away and in different places. I wouldn't even consider the MX/CA coastline as a good measure.

Mark

[a64pilot]

I've done some reading and now understand why strapping is preferred or at least I think I do. Never thought of a roofing supplier though.
I think if I understand that tieing into a seacock and apparently my engine block with strapping is the way to go, but what about my lifelines and my Solar panel mount? All the ones aft are now SS steel tubing, and I'm thinking that the big, flat area I have above my davits that contains three 250 W panels, would make a very fine ground plane? Has to be about 60 sq ft or so of perfectly flat metal frame.

Any chance of electrolysis tieing to a thru hull?

Assuming I go with a whip as I think I will and may go with a backstay too when I get the rigging changed. I have a very busy stern area now, what with Solar panels, davits and Radar pole etc., and don't think a whip would make that much difference, and like the idea of God forbid I lost the rigging, I may still have an SSB antenna.

I will continue to read, one thing I have read continuously is there is no "perfect" install, it varies too much from one boat to another, and darn near anything will work antenna and ground plane / counterpoise wise, just some things work much better than others, so even if you get it working, it may not be working very well at all, GAM antenna I believe may be an example of that.

So assuming a whip, which one performs best as an antenna? There is a wide variation in price even within the Shakespeare brand.

Now a whip radiates from it's tip? So if I mounted one right beside my Solar panels and they are at 5 ' above the base of the antenna, they won't hurt performance? I was thinking using the panels to support the antenna, I assume there are no free standing 23' whips?

[a64pilot]

Rich,
I understand your point, and I wasn't going to buy an SSB until just before we go, as I don't need one now, like a watermaker for instance, but this "deal" sort of just popped up and I thought what the heck, this year or next, what difference is there in one year?
A lot of cruising "infrastructure" exists, that I am not aware of, and if I eventually nug this thing out myself, I will be I think in a better position to fix it when I have to. So far I have done all the equipment installs on the boat myself, some I am sure would have been done better by a professional, but I do know where every wire etc runs, if I can remember anyway

This site has been a wealth of knowledge and assistance, you do have to be a little careful sometimes of who's opinion you consider, but usually you can tell who knows what they are talking about and who doesn't.

[colemj]

Shakespeare makes free standing 23' and 28' whips. We have a 28' on our arch that is 6" away from the solar panels - no problem.

A whip does not radiate from the tip (well, I suppose it could under specific frequencies and counterpoise). All a whip is is a supported random wire - just like a backstay.

If you install a whip, you should make sure that it is above your counterpoise (no mounting the whip on deck and using your arch as a counterpoise, as well as keep as much as possible away from grounded metal above it (I have seen them mounted right against a grounded arch that extends 6-10' up the whip).

Mark

[btrayfors]

a64Pilot,

Cudos for your reading and investigating and asking, but IMHO you're making this much too complicated. And, obsessing over RF grounds is really unnecessary.

If you really do have an IP38 as your signature says, the solution for an RF ground is already there and is very simple: use the s/s rubrails. I've done this with several IPs, and they work just fine. Just run a short length of copper (flat strip or large cable) from the tuner ground to a bolt passing thru the rubrail. Then, make sure there's a good electrical connection between the sections of rubrail on whichever side of the boat you're using.

For an antenna, I'd probably use an "alternate backstay" solution: a random length of insulated 3/16" s/s lifeline. Make a loop at each end, using Nicopress sleeves. Hoist the upper end with a spare or dedicated halyard, tie the lower end to the pushpit on whichever side you choose. Make sure the main will clear OK (not too much roach). Use GTO-15 transmission line from the tuner up thru a deck fitting to the lower end of the antenna. No need for insulators; a 1-2' length of 3/8" Dacron or poly line will work fine.

Simple. Inexpensive. As permanent as you want it to be. Very robust (mine stood up to five -- yes, five -- hurricanes in the BVI over an 11-year period. And, it works. Very well.

73,

Bill
WA6CCA

[a64pilot]

Well Bill, I can assure you I do really have an IP 38, hull #41. I haven't looked but assume the hold down screws do penetrate through the hull and have nuts on them as opposed to being just wood type of screws that I assumed them to be.
That's it, that is all the ground plane you need, you don't benefit from having more or a much larger surface area? Just use one, no need to connect them both?
Do you run this "alternate backstay" between the existing ones I assume or otherwise it will run right alongside one or the other?
Why vinyl coated line? I have a whole spool of SS aircraft control cable that I was going to replace my vinyl coated lifelines, surely it would make a good antenna, just cover the bottom part where it could be touched to prevent being burned?

On edit, what is the ideal length? I know that changes of course with frequency, but as an average, what length is best?

[btrayfors]

Ah, yes...the IP38 has two backstays. My bad. And, I believe, they are two full backstays, not one with a split. That makes it easy: just insulate ONE of the backstays.

I'd probably install a single insulator (preferably a Haydn fail-safe one) near the top, and feed the backstay belowdecks at the chainplate.

For the rubrails, it doesn't matter how they're installed now. Just remove one of the fasteners and install a bolt long enough to pass thru the rub rail, the hull, etc. Then, a short length of GTO-15 wire from the tuner ground lug to the bolt.

Yes, a single rubrail is enough. While in theory this could be improved by adding additional radials, tying in belowdecks metal, etc., in practice it won't make much difference. Try it with just one rub rail first and see how it goes.

There's a lot of garbage and misleading half-truths in the wonderful world of RF. The famous "100sq feet of metal" is perhaps the most glaring of these, but there are lots of others. "Don't use wire...you have to use flat ribbon because RF travels on the outside, not the inside". Garbage. A half half-truth. Wire works just fine in most cases. Think about it: one of the simplest and most effective antennas....against which all other antennas are compared, by the way....is the dipole antenna, usually consisting of two equal lengths of wire capable of carrying and radiating thousands of watts of RF, and requiring no external RF ground.

Insulate one backstay. Tie the ground to one rub rail. You'll be happy.

Bill

[ka4wja]

A64,
Bill's succinct advice here is good!!
And, his comment about "obsessing over RF grounds" is spot-on....(and of course, parallels my comments from yesterday of, "much to do about nothing much")

Originally Posted by btrayfors

a64Pilot,

Cudos for your reading and investigating and asking, but IMHO you're making this much too complicated. And, obsessing over RF grounds is really unnecessary.

If you really do have an IP38 as your signature says, the solution for an RF ground is already there and is very simple: use the s/s rubrails. I've done this with several IPs, and they work just fine. Just run a short length of copper (flat strip or large cable) from the tuner ground to a bolt passing thru the rubrail. Then, make sure there's a good electrical connection between the sections of rubrail on whichever side of the boat you're using.

For an antenna, I'd probably use an "alternate backstay" solution: a random length of insulated 3/16" s/s lifeline. Make a loop at each end, using Nicopress sleeves. Hoist the upper end with a spare or dedicated halyard, tie the lower end to the pushpit on whichever side you choose. Make sure the main will clear OK (not too much roach). Use GTO-15 transmission line from the tuner up thru a deck fitting to the lower end of the antenna. No need for insulators; a 1-2' length of 3/8" Dacron or poly line will work fine.

Simple. Inexpensive. As permanent as you want it to be. Very robust (mine stood up to five -- yes, five -- hurricanes in the BVI over an 11-year period. And, it works. Very well.

73,

Bill
WA6CCA

Here's what I wrote yesterday...

Originally Posted by ka4wja

With all the talk here about antennas, grounds, etc...most of which is "much to do about nothing much"
We shouldn't forget that after the antenna, the single most important part of the system for effective HF Voice radio operation...and that is the operator!!!
<snip>
I'm just using a bit of sarcasm to make the point that we tech-savvy sailors (myself included) have failed to emphasize the basic radio education of our fellow sailors....and instead get involved in the minutia of things which, as I wrote above, is mostly "much to do about nothing much"!!


I hope this helps...

Fair winds...

John

And finally, although I've never been on an IP38, with those rig dimensions and depending on exactly where you install the tuner (lazarette / stern locker), as well as how many feet away from the masthead you place the upper end of the antenna (3' - 5'), I suspect that your "alternative backstay antenna" length will be right at the "standard" recommendation of 40' - 45' overall (including the length of GTO-15 wire...

So, along with SS rub rails (and if you're a fanatic like me....pushpit, lifelines, alum toerails, etc. and even possibly a close-by bronze thru hull), you can have a darn good set-up....all with low-cost AND longevity!







EDIT: (Upon seeing Bill's most recent post)
I appreciate the reinforcement of debunking the 100 sq ft of copper myth!!! (now if we could just get Guest, etc. to stop marketing Dynaplates spec'd with their "comparable to xx number of sq ft of copper!!!)
And, yes....copper wire works!!


A64, I do agree that doing what Bill recommends will work fine, and you should be quite happy with it....
But, if you've got the time and are doing a fit-out anyway, I also think getting a direct sea water RF ground connection is good...not a necessity, but a good idea nonetheless...
No arguments here....just a slightly different opinion....(and I don't either of us is "right" or "wrong"....just different...)








Fair winds..

John