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Still holding its own - HF Radio

22K views 25 replies 14 participants last post by  Capt Len 
#1 · (Edited)

Still holding its own - HF Radio
by Jeff Williams
A backstay makes an excellent antenna with an antenna tuner and insulators to keep it electrically isolated from the rest of the rig. If you're thinking about that first offshore passage, you have to face the need for long-range communications equipment on board. Life is easy along the U.S. coast: VHF radios can talk to other boats and hear National Oceanic and Atmospheric Administration (NOAA) weather broadcasts, cell phones and smartphones keep you in shoreside contact and allow you to surf the Web, and most marinas offer Wi-Fi. But once out of sight of land, everything changes.

Offshore communications equipment can be classed as satellite-based or terrestrial-based. A fundamental truth is that compared to most terrestrial systems, satellite communications systems are more expensive to operate. With satellite communications - whether voice or data - you will pay by the minute or by the byte, on the order of $1.00 per minute or more. Additionally, satellite communications systems operate like telephones - they are used for point-to-point communications only.

In contrast, high frequency single-sideband (HF SSB) radios cost nothing to operate and they can be used for both station-to-station operations and for broadcast transmissions and reception. That means you can listen to local or regional "nets" of boats and weather situations as well as broadcasts of weather forecasts and radiofax charts. They are essential for distress situations, allowing contact with nearby ships and regional rescue centers. HF radios can - with additional equipment - also be used for sending and receiving e-mail.

Satellite communications offer certain advantages with their telephone-like operation, but they cannot deliver the casual boat-to-boat communications that are pervasive in the cruising community. Nor can they provide weather information as cost-effectively as HF radio.

HF SSB units from Icom (top) and Furuno.
HF radio continues to enjoy a dominant position in offshore communications within the cruising community. Cruisers that I've spoken with that have satellite but not HF radio equipment on board have lamented that decision. A good quality HF receiver should be considered the bare minimum for offshore work. A transceiver and antenna tuner are the preferred equipment. Adding an e-mail modem completes the communications suite.

Choosing the right equipment

Choosing the right HF radio is important for ensuring reliability and ease of use. Generally, radios used by cruisers are either commercial marine radios or ham radios. Looking at ham radios, you'll find a broader range of manufacturers, features, cost, and capabilities, but unless you're a licensed ham operator and really love fiddling with knobs and pushing buttons, it's better to look at the commercial marine radios. Also, ham radios do not support digital selective calling (DSC), a growing requirement for marine applications. Hams, this doesn't mean you can't still operate on the ham bands. Most marine radios offer options that open the radios up to include the ham frequencies for licensed operators.

Within the recreational segment, the commercial marine radio market has been dominated by Icom and Furuno. Their radios have respected performance specifications and support e-mail operation. Lower quality radios may perform adequately for voice communications, but will not stand up to the higher demands of data communications.

You must also install a separate antenna tuner. Unlike VHF radios which operate over a narrow range of frequencies and thus can operate with an antenna permanently "tuned" to the VHF band, HF radios operate over wide frequencies and numerous bands requiring the antenna to be retuned with each frequency or channel change. The commercial marine radios mentioned above all have companion automatic antenna tuners available.



Radio installation

Most problems with HF radio operations can be traced to poor installation practices. With a good installation, however, HF radios will operate reliably and effectively; consistent, robust contacts at distances of 3,000 miles and more are routine for this equipment.

When installing the transceiver, it is important to have sufficiently sized power and return wires from your 12-volt distribution point. I emphasize return because many people forget that the negative side of the DC power connection carries just as much current as the positive side. And notice the use of the word return, not ground; do not use your ship's bonding ground for negative return.

To choose the right wire size, use charts like those found in the West Marine Advisor on Marine Wire or Marinco's technical information on Ancor wire. These are based on requirements set by the U.S. Coast Guard, ABYC, and associated national standards.

As an example, if you measure the distance from your power point to the transceiver as 10 feet, then you must use two times 10 feet (20 feet) as the length of the circuit (remember, power plus return). Refer to your owners manual and find the maximum current draw for the radio at full power. The Icom-802, for example, requires 30 amps. Using the West Marine table for 3 percent drop (not 10 percent drop), enter the table from the bottom on the 20-foot line. Go up the line until you read across to 30 amps. You will find you need AWG 6 wire size for this installation. Marinco provides the same information in a tabulated format.

Make sure that you have a sufficiently-sized circuit breaker for your transceiver as well. In this case, it must be at least 30 amps. Forty or 50 amps would be better to avoid unwanted trips when the radio is operating at its maximum output power. Keep in mind that circuit breakers are sized to the wire runs they are protecting based on the wires' ampacity. From the Marinco information, the ampacity of AWG 6 wire is 102 amps, thus a 40- or 50-amp breaker is safe.

Use a high-grade marine wire - pre-tinned copper stranded wire is best. The tinned conductors resist corrosion much better than bare copper. In general, only stranded wire should be used on boats to resist stress fatigue due to vibration. It is much easier to work with as well. (For more good tips on wiring, see Harry Hungate's Practical wiring in issue 200, March/April 2012.)

Terminals should be crimped and may be soldered as well. Crimping is preferred as it produces a solid mechanical bond. I prefer to both crimp and solder - the crimp provides the mechanical strength and the solder prevents moisture intrusion into the bond. Residue solder flux should be cleaned from the connector with alcohol. The crimp and insulation end should then be covered with a section of adhesive-lined heat shrink tubing. The heat shrink inhibits moisture, acts as a strain relief, and reduces flexing at the bonding point. It's expensive, I know, but the alternative is less reliable electrical connections that you'll have to diagnose at night in heavy seas during a gale.

While you're in the neighborhood, check to be sure that the wiring from your batteries to your power distribution point is adequate to the task as well. If you're working on a refit of an older boat, you may find that the wiring to the fuse or switch panel isn't big enough to support the addition of an HF radio. You may need to make your connection closer to the batteries themselves.

The transceiver will also require a ground bond. We'll come back to this later.

The use of short pieces of PVC tubing to hold the antenna feed wire off the lower part of the backstay (just above Jeff and Raine Wiliams' ship's cat Carib).
Antenna tuner installation
The antenna tuner is an essential part of your HF radio installation. Its function is to match the electrical properties of your antenna to the output of the radio at every frequency that you choose to operate on. Think of it like a camera lens - if it isn't in focus, it's not going to work. Without a tuner, you could easily damage your nice, new transceiver and other electronics on your boat. Regardless of its catalog descriptor, it is not an "option."

Your HF antenna actually starts at the antenna tuner. Remember this: the wire connected to the antenna terminal on the tuner is part of the antenna. For this reason, correct location of the tuner is very important. You want to minimize the length of the wire and any bends in the run from the top of the tuner to your antenna proper. The tuner should be out of the weather, but close to any overhead through which the antenna wire will run.

To complicate things a bit more, coming out of the opposite end of the tuner is the connection to the counterpoise or RF ground. The length of these connections into the RF ground system also need to be minimized. It's a balancing act to pick a good location, but give preference to optimizing the antenna lead run from the tuner to the antenna proper.

An antenna tuner basically has four connections: power and control from the transceiver, a coaxial connection carrying the radio signal to/from the transceiver, an antenna connection, and an RF ground (or counterpoise) connection.

The first two are relatively easy. The transceiver manufacturer will supply or sell a recommended cable for the power and control. They may also specify a maximum length for this.

The coaxial cable must be low loss, 50-ohm cable. Typically recommended cables are RG-8X and RG-8U, and these should be marine-grade with pre-tinned conductors. It's a little tricky soldering coaxial connectors, so you may just want to purchase a good marine-grade cable of the length you need with connectors already installed. Don't use multiple cables with additional connectors - each connector contributes to losses in both transmission and reception. Again, I would recommend adding adhesive-lined heat shrink or self-vulcanizing tape to the exposed end of the connector to reduce moisture intrusion.

Antenna
Your HF radio antenna will probably be either a long fiberglass whip or an insulated section of standing rigging. If you are using a whip, you may have some flexibility in placing the antenna. Try to keep it several feet away from all other antennae. Remember your HF radio can put out 150 watts of power.

If you are using an insulated stay, a backstay is best - shrouds tend to be complicated to insulate because of their connections to spreaders and their radiating properties are compromised by being parallel to other shrouds and the mast itself. The upper insulator for the backstay should be four or five feet from the top of the stay; the lower insulator should be at or above eye level for safety. In any event, the length of the insulated wire should be at least 20 feet.

Use a good quality high-voltage wire, such as GTO-15, to run from the antenna to the tuner. Keep in mind this wire is part of your antenna: keep it away from other wires and antennae, run it as straight as possible, and don't put any unnecessary kinks, bends, or loops in it.

Attach the wire to the upper wire terminal of the backstay insulator using a stainless steel hose clamp. Before you do this, strip back an inch of insulation from the GTO-15 and use a soldering iron to pre-tin the wire with additional solder. Clean the flux from the connection with alcohol, then use adhesive-lined heat shrink to seal the insulation end from water intrusion. This end is going to be out in the weather and pointing upward, so seal it well. Take a small piece of copper foil and fold it over the wire end to make a wire sandwich. Clamp this sandwich to the terminal and then wrap all with self-vulcanizing tape.

If you run the wire lead along the lower (uninsulated) section of the backstay, use short pieces of PVC pipe to make plastic standoffs about three inches long to hold the wire away from the stay. Loop cable ties through the PVC and around both wires to hold them in place.

Also, check your backstay's lower end for a connection to ship's ground. If there is such a connection, remove it. You do not want several feet of grounded wire running parallel to your antenna wire.
Attach the lower end of the GTO-15 wire to the antenna terminal on the tuner. Once again, it's a good idea to pre-tin that bare wire and seal the insulation.

RF ground
The RF ground serves several purposes in the antenna system. In one respect, it's a mirror to reflect signals radiated downward by the antenna. In another, it balances the antenna system, reducing power losses from the transmitter. Without it, the signals from the antenna will try to reflect off of everything metallic in the boat and unwanted power will be absorbed by equipment, causing all sorts of interference to instruments, radios, autopilots, etc.

Conceptually, imagine yourself on your antenna looking downward: you need to see as big a reflective plane as possible. Obviously, the seawater would make the perfect reflector. Unfortunately, filling your boat with water violates boating rule number one about keeping the water on the outside.

Some good examples of metal that can form a counterpoise are metal toe rails and stanchion bases (and lifelines). You can also use metallic tanks, an external ground plate (such as a Dynaplate), and a lead or iron keel. You create the ground plane by interconnecting these and tying them to the antenna tuner.

Radio frequency energy behaves a bit different from the DC that you're accustomed to from the ship's batteries. RF travels on the surface of conductors and not so much inside a wire; a phenomenon known as skin effect. Copper foil is an excellent conductor of radio frequencies; it should be used to tie your RF ground components together. You can fold over the corners of the foil to form a thick layer, drill a hole through the layers, and attach the foil to bolts in this manner.

An excellent ground plane can also be established in fiberglass boats by incorporating a square yard or so of copper screen in the layup of the hull below the waterline. The radio frequency energy actually couples from the screen to the seawater through the hull. You can add the screen onto the inside surface of the hull and cover it with epoxy to create the same effect. Solder a copper tab at some convenient place to make the foil connection.

In summary, run copper foil from your tuner to toe rail bolts on both sides if possible, to any nearby metal tanks, to copper screening laid up in the hull, to a keel bolt, and to the HF radio's metal case (the previously deferred transceiver ground). Your RF ground should be tied to ship's ground at just one point if possible.

On our J/40 Gryphon, our HF radio installation evolved during the first two years of cruising. We ended up with an Icom M-710, automatic antenna tuner, copper foil to toe rails and Dynaplate, and an insulated backstay antenna. Once these systems were in place, we consistently succeeded with 3,000-mile contacts for weather information and e-mail communications across the Indian and Atlantic Oceans. And we still do.

Jeff & Raine Williams sailed their J/40 Gryphon around the world from 1998 to 2004. They sailed Gryphon again to New Zealand in 2010 where they are now based.
 
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4
#2 ·
Excellent article by Jeff, and a good summary of the value of SSB and of installation basics.

I install SSB's professionally, and I have just two things to add.

1. Fusing/circuit breakers. Jeff's right that good clean power to the radio is essential, and the example he gives is right on: AWG6 marine cable for runs up to 20' round trip, AWG4 for longer runs. However, you need a fuse or circuit breaker in BOTH the positive and the negative wires, located close to the house batteries. And, most circuit breakers will not meet ABYC specs insofar as ampere interrupt capacity (AIC) is concerned. AIC must be in excess of 5,000 amps, and only the new high-AIC Blue Sea Systems breakers will meet this standard. Much easier to use fuses. Two common types are OK for this purpose: ANLs and MRBFs. The smallest ANL you can find is 40A. MRBF's come in 30A sizes and up.

2. RF Grounding. This is a little understood part of SSB installations. The implication in Jeff's article is that wire can't be used because RF travels on the outside of conductors, so only use wide copper, etc. This is WRONG, despite how often you see it repeated in manufacturer's instruction manuals and in texts on SSB. If that were true, how would a wire dipole work? And how come it's the STANDARD against which all antennas are measured?

The use of aluminum toerails, lifelines/pushpit/pulpit structures, metal rubrails (like on Island Packets), and other solutions can work fine, but sometimes are a lot of work to implement. Radials, both tuned and untuned, work very well. There's no need to physically couple to the seawater. In fact, the evidence is that elevated radials work better than buried radials. One of the simplest effective solutions is to use the KISS-SSB Radial Counterpoise System....very easy to install, and it works as advertised.

Again, thanks to Jeff for his excellent summary of the use and value of SSB to the cruising community.

Bill
WA6CCA
 
#8 ·
Bill, I fully agree with most of what you have said except for your miss-understanding of skin effect. This is truly an effect of wire. I remember way back when I first started learning electronics in 1965.

The short version was when you run DC, the current flows across the entire diameter of the wire. As you increase the frequency it moves to the skin which actually represents a slight increase in impedance for the same level of voltage. Then the kind of funny part was when it get s high enough it leaves the wire and hence wive guide was developed. Wave guide is you have not used it is really coax without the center conductor.

In saying that at HF frequency, some of the signal clearly goes down the wire, but to your point a wire dipole makes a great radiator/dipole antenna.

Twin lead is an interesting concept that works well, but that does not mean that there is no skin effect. :)

I found a boat where a "Professional Installer" had installed GTO 15 between the Transceiver and the AT140 tuner. It had a very poor radiation as a result of the maximum possible reflected wave. So wire in RF is more than just wire, skin effect, etc. It also requires impedance matching to work in many cases. The Kiss ground is great, but it is really the other half of your 1/2 wave antenna using custom cut radials. e.g. a 1/2 wave dipole with the modifications made by the tuner to match the kiss and the back stay.

Terry AD7XL
Made Simple for Cruisers
 
#3 ·
I would not be with out my HF but I will be getting a sat phone for some locations like the Kimberleys in Australia where Hf just does not always get in or out of the gorges. As for Ground plane using the 3" copper tape I have been told to place two strips 3" apart this gives you a 9" wide ground plane.
 
#4 ·
Hello All:

I installed an Icom 802 in my IP40. After much debate and concern over how to cut thru all the underfloor bulkheads with copper foil for a counterpoise I opted for the Kiss method radials. After an easy half hour installation of the half inch tubing from my tuner forward to the empty area over the galley I was ready.

I have easily contacted Hawaii over Pacific Seafarers net at a distance of 2500 miles and have on good days talked as far away as NZ and Aus. So far I do not regret this method at all-and it sure is easy compared to the alternative!

Wayne
SV Music
May the force be with you!:)
 
#5 ·
Hello All:

I installed an Icom 802 in my IP40. After much debate and concern over how to cut thru all the underfloor bulkheads with copper foil for a counterpoise I opted for the Kiss method radials. After an easy half hour installation of the half inch tubing from my tuner forward to the empty area over the galley I was ready.

I have easily contacted Hawaii over Pacific Seafarers net at a distance of 2500 miles and have on good days talked as far away as NZ and Aus. So far I do not regret this method at all-and it sure is easy compared to the alternative!

Wayne
SV Music
May the force be with you!:)
Could you please elaborate.
 
#6 ·
Hello Simon:
The Kiss-SSB method used is as simple a method as possible. One attaches the lead end of the 10 foot long 1/2 inch diameter tubing to the antenna tuner then strings the tubing out wherever it will fit. See kiss-ssb.com/ for their counterpoise. I was just reinforcing what Bill btrayfors said in his treatise above.
Putting all that 3 inch wide copper in is not very easy and nearly impossible in some boats whereas the Kiss-SSB counterpoise couldn't be simpler and is effective. The method(tuned radials) is eluded to in the ICOM manual as well. Cheers Wayne
 
#11 · (Edited)
I am looking to replace the copper foil as it has deteriorated in a couple of spots, I like the sound of the KISS-SSB counterpoise. But I am skeptical, it goes against all I have learned over the years. Convince me please, as I plan to replace the copper in December.
 
#21 ·
Can't you repair it? I would think copper strapping is superior to KISS.

While I haven't tested them against each other I'd bet dollars to donuts that the KISS counterpoise will work better on a narrow band of frequencies, while the copper strap, bonded to sea water will give better performance throughout the band, and a more evenly distributed antenna pattern.

Both the backstay and the counterpoise will work well on their natural frequencies. If you can choose those by selecting the appropriate lengths, you might have fantastic performance but not everywhere. I don't know what they use for the counterpoise, a larger diameter wire will a give broader bandwidth.

However, if you are like me, a HAM, and an electrical engineer that specialized in antennas, you will choose the copper strapping. Seawater is a great ground plane. I signed in to the century net on 80 meters one night at Block Island and being maritime mobile in a small state everyone on the net wanted to talk to me. I was talking to California, the Virgin Islands, Florida and every place in between. Copper strap works great.

By the way, I see no reason why bonding both of these together would not perform better than either.

I recently purchased a used M802 on eBay, and its antenna tuner, that was pulled from a Sport Fisher, and damaged in the process. I replaced a few damaged components and it is ready to go. I just need to put up an antenna for it.

From what I've seen so far, it won't replace my Ham rig. I do like the 150 watts of power. My Ham rig is 100 watts and the extra 50 watts makes a big difference. I am testing it out at home before moving it onto the boat.

I'd advise anyone who purchases a SSB radio to spend a lot of time using it, playing with it, and learning every function and capability of the radio so that it is second nature.

Using it on the Ham bands is a good way to do that. The 40 meter band is nice for daytime use, but at night the band goes long and these frequencies are European commercial broadcast stations that boom in at night. So everyone moves to 80 meters--the popular nighttime band for hams. Both are on Lower Side Band (LSB). These bands provide great regional coverage albeit they tend to be a bit noisy as lighting and other natural phenomena cause interference. By the way, convention is that LSB is used below 10 MHz and USB is used above 10 MHz.

If you don't have your Ham license, you should get it. Hams spend a lot of time on the radio talking about antennas and radio, so you can ask and get lots of free advice. Hams will track you as you travel on the ocean and can be used to alert authorities if you don't check in. Get your ticket! It only cost about $6.20 and is good for ten years! What a deal! And high seas email is free on the Ham bands.

FYI. Any Ham's that want to use the M802 on the Ham bands, I found this link. It looks pretty easy, and you don't have to cut any traces or remove any diodes inside the radio, it is all done with software.

Ham/Mars Mod:

http://www.docksideradio.com/PDF Files/M-802_Programming.pdf
 
#12 ·
I met the designer of the KISS system at the Seattle Boat Show. I'm no HAM myself but I can usually smell bull$h!t marketing and this guy seemed totally legit. Not a whiff of snake oil anywhere. He's done some impressive sailing as well and pioneered a new route from New Zeland back to the USA West Coast via Easter Island. It's apparently now a well-enough used route by cruisers. He has been a ham for something like 50 years as well. I think the KISS system has been around a while. You might ask over at CF if you go there and see what people say about it. I recall doing some research recently on it and the reviews of owners seem to be glowing.

I was able to handle the KISS thingy myself. It's as simple as could be and basically looks like a longish coiled vinyl coated wire. Apparently you connect it up, and toss it in a locker, or stretch it out (doesn't matter) and Robert's your mother's brother.

Simon, You mentioned going to the Kimberlies. That's an area I am really looking forward to sailing when we get back down under. What resources are you using for trip planning? Books, websites, blogs? Can you let me know by PM or post where to look for that info? Thanks!

Medsailor
 
#13 ·
Med-
" I think the KISS system has been around a while."
There's a saying among ham operators that you can use a lawn chair or a light bulb as an antenna and either one works fairly well. That doesn't mean they are GOOD antennas, it just means they can be made to work.
I think the KISS autopsies have proven beyond any doubt that if someone is afraid to use a tape measure and wire cutter, the KISS antenna is a very nicely made solution. Just connect it, and it will outperform the lawn chair or the light bulb.
Does that make it a good antenna? Depends on how you subjectively define "good". Does that make it a cost-effective antenna? Depends on how much you value your time, or fear of tape measures and wire cutters.

Some folks can't change a flat tire, they call the AAA. For that crowd, the KISS antenna is probably a very reasonable solution. For those who want substantially higher performance levels and don't mind doing a little work, there are other solutions. There's no debate, no mystery, involved here. What it is, and what it can do (on a relative or absolute scale) are all simple physics. Which of course is a mystery to many folks.
 
#14 ·
I have done the research the best I could, and given the best price I could find for copper foil to replacing my old green and brittle counterpoise (ground) is $155. The Kiss-ssb seems to win price wise, and given that no one has stated it wont/does not work, and a lot of folks who have and use it, say it works great for them. I have ordered it and it will be in Brisbane when I get there from my travels. How it works I still don't know, Hey the bumble bee shouldn't fly but it does. I will let you know how it goes.
 
#15 ·
I have all the parts and was about to re commission the Hf (Icom 802). BUT as the kiss-ssb is a sealed unit and is attached to the ground point on the auto tuner (icom AT-140) How or do I still need to ground the unit to a boats ground? Both the tuner ground and the transceiver ground are grounded to each other via a wire and would normally be grounded via copper foil fixed to The though hulls. As the kiss-ssb is not technically/physically grounded, should I run a grounding wire to say the rudder stock. Will this counter the KISS-SSB.
 
#16 ·
I think the whole point of the Kiss is that you don't have to ground it to anything. If you do, I'm not sure it would be better or worse.

Any way you can test it both ways? Transmit and see if the Martians respond with KISS and see if the beings from Jupiter respond when the KISS itself it grounded?

MedSailor
 
#17 ·
Simon, the whole purpose of a counterpoise device (the KISS) is to replace grounding and make it unnecessary. More is not necessarily better. If the instructions it came with were unclear, I would suggest contacting the company directly to ask them if they think it should be used alone, or with other grounding connections.
 
#18 ·
Hello Simon

As I understand it and as I've done with my boat, you only connect the KISS to the tuner ground and NOT to the ground plane you may have already. The KISS is stand alone here to form the counterpoise with no interconnection to anything else.

However, the transceiver chassis must be connected to a thru hull etc for a ground. I've cnnected the chassis via a 3" wide copper to a thru hull. The ground between my tuner and transceiver is not connected.

My system works great!

Cheers
Wayne
 
#20 ·
I chatted with the maker of the KISS, and found him to be very helpful. You can tell from the way he runs his company, that he really believes in his product and was very responsive to questions.

My question to him was similar to SimonV's question. The response I got back was you only have to hook up the KISS to the tuner, and don't need to run foil between the transceiver and tuner, or connect anything by foil to any ground. As the manufacturer of the KISS pointed out, on the ICOM M802 the tuner and the transceiver are already connected via the control cable and there is no reason to ground everything using foil. I was a skeptic, but gave it a try and it did work. And very well at that.
 
#22 ·
I have a friend who has become interested in helping me install HF on my boat. His goal is to use the existing rigging without modifying it except to add feed points. We ran a first experiment last weekend and had good success. We were able to transmit and receive at a preplanned distance of 200 to 300 miles.

His plan was to use the lifelines as a make-shift counterpoise. He fed the backstay in hopes of getting a loop antenna out through the backstay and forestay in the future. For this round, the loop was not complete as the antenna feed was at the base of the backstay with lifelines used as the counterpoise. All of this was set up with alligator clips and a bit of wire (very kludged up). On the first try we were talking with his friend about 220 miles away in Cedar Rapids, IA. While they were talking, a person from Minneapolis (320 miles from our location) joined in. Everybody was clearly heard. This was so much fun. Really cool stuff.

For those who care, we were using 40 meters (7.0 to 7.3 MHz). Also, the plan was to talk with Cedar Rapids (from Waukegan, IL). The band was chosen for this purpose. We didn't try longer distances....yet.

His goal is to be able to use as much of the HF band as possible by adding feed points....no added counterpoise, no copper sheeting on the hull, no modifying the rig, etc. I have a lot of confidence in his ability. We will see how it progresses from here.
 
#23 ·
Your friend sounds like he knows what he is doing, and I'm sure things will work out fine.

I have done some modeling of the radiation patterns of an insulated backstay versus no insulation and just letting the entire rig be the antenna. The difference is actually much less than you would expect, and in my opinion is pretty insignificant.

Of course, if you don't insulate a backstay, then you have to be very careful that the energized portion of the system and the counterpoise are never joined. For example, if you have a keel-stepped mast, and there is a metal-to-metal connection there between the step and the keel itself, you may have a problem. Or if your keel is exposed to bilge water, and your counterpoise is also able to couple to the bilge water, you may have a problem. Then, too, there is the issue of RFI if you are radiating from your entire rig.

Still, if you can work around these sorts of issues...
 
#24 ·
Back in the day ,used to build a copper mesh into the cabin top to act as a ground plane and keep stuff insulated; ocean ground plane just seemed to attract electrolysis problems .Used long tall whips and an inline gizmo to change the antenna characteristics. I know it's an older thread, but just came past it and had to offer my ha'penny.
 
#25 ·
"Back in the day ,used to build a copper mesh into the cabin top to act as a ground plane "
Len, technically that would be a counterpoise and not a ground of any kind. One can be just as effective as the other, and the two terms are often interchanged, but they are different and a primary difference is that there is no electrical ground, no risk of galvanic actions, etc. , from a counterpoise. Which can also be made to match a resonant length for the antenna it is being used with.

The inline gizmo is usually an antenna tuner, and again, that's often misunderstood. An antenna tuner doesn't actually "tune" the antenna, what it does is eat the radio energy which is being reflected back from the antenna, that otherwise would enter the radio and typically damage or destroy it. A good purpose--but it doesn't make the antenna any more efficient, it is just a "spatter shield" that is blocking the "spatter" coming back down the antenna cable. An antenna can radiate power, or absorb power, or spit it back at the radio. Radiating power is the best trick. Absorbing power is a great way to hide a poor design because it "matches" everything. But for practical reasons, an antenna tuner is usually the best solution. Pretty much like a "lobster bib" when you're eating lobsters.(G)
 
#26 ·
Thanks for the clarification .hello. That brought back much that I'd forgotten about what I only sorta knew. Wasn't my main area of interest anyway. I was out there to catch fish. Like I don't need to understand boolean algebra to use Google or shear lambdas's frequently to see .
 
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