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Old 03-06-2015, 17:58   #16
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Re: Recommended coax for triatic stay HAM antenna

Run coax from the radio to the tuner input and any good quality wire from the tuner to the stay. LMR 240 or 400 are both good choices and you can easily find their relative loss on the intetnet so won't bother quoting their characteristics. Consider the latter can be more easily waterproofed at the connector(s).
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Old 03-06-2015, 18:38   #17
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Re: Recommended coax for triatic stay HAM antenna

If I have to put the tuner on the top of the mast:
1) I have to buy a new tuner, would the IC-AH4 be ok? ($230)
2) I need to buy some kind of cable (RG213?) to run from the IC-7200 at the nav table to the mizzen masthead (~approx 20m or 60ft)
3) I need to buy a 4 conductor cable to run the same distance for the tuner power and control (how small gauge can I go?)

Otherwise, I can put the tuner in the salon:
1) run a 40ft coax from the IC-7200 to the LDG Z-11 Pro 2 in the salon (already own this cable)
2) Extend the existing control cable 40ft (Do you think cat5e would suffice? Combing the 8 cables into 4? If so that would be 0 cost as I have the cat5e)
3) Connect the LDG tuner to the main upper shroud (with what kind of cable? I've got a 1ft coax, could I cut the connector off one end and just ground the shield and connect the main wire to the chainplate?)
4)Will they have to isolate both sides of the spreader?
5) Still isolate the triatic and jumper the shroud to the triatic
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Old 03-06-2015, 20:15   #18
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Re: Recommended coax for triatic stay HAM antenna

Yes, you'd probably have to insulate the tip of your spreader. My friend had a special non-conductive fitting fabricated for his mizzen spreader.

The AH-4 is a great little tuner.

One problem with putting the tuner atop a mast: what will you use for an RF ground? The non-insulated rigging? The mast itself?

This might sound wanky, but since you already have a tuner, why not try to load up the whole uninsulated rig and see what happens? Sometimes this works better than you'd think.

Just run GTO-15 from the tuner to the nearest bolt thru a chainplate, run a ground of some type (KISS? Copper strap to a bronze thru-hull? Radial ground wires?), and see how that goes. You may be surprised.

What ever you do for a multi-band antenna, it's going to be a compromise on your boat. However, for a dynamite single band antenna, e.g., on 20 meters, you could build a simple vertical dipole and string it up forward halfway between the mast and the forestay, tied off to the toerail on either side of the bow. This will perform better than any other antenna you can fashion on a sailboat, but it is limited to a single band.

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Old 03-06-2015, 20:58   #19
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Re: Recommended coax for triatic stay HAM antenna

Another thought, and this might work for you. It's even pretty close to your original plan.

If instead of a tuner atop the mizzen you put an UN-UN there, you could then run coax from the UN-UN to the tuner located belowdecks. Then, from the UN-UN you run GTO-15 feedline to the insulated triatic stay. And, of course, you ground the UN-UN to, e.g., the mast or rigging.

This could work quite well. It also has the advantage of only requiring a tuner which can tune coax, like the one you already have. These can work extremely well, even with built-in tuners in some HF rigs.

The best source of an appropriate UN-UN is probably Balun Designs: Balun Designs LLC - High quality baluns and ununs at reasonable prices These guys are wonderful and for about $75 will build you a special UN-UN which is designed for your installation. Just give them the specifics, i.e., the insulated length of the triatic and the overall length of the coax. Tell them also which bands you plan to work, and which are most important to you. And, if you should ever decide to run some real power, these UN-UNs will easily handle it.

Anyway, suggest you call them and discuss your idea. Could be a relatively simple and effective solution.

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Old 03-06-2015, 21:32   #20
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Re: Recommended coax for triatic stay HAM antenna

Our boat has bonding wires all over it that run to thru-hulls, multiple chain plates, stanchions, you name it. It would be pretty tough to isolate the rig from the ocean, so I've never considered lighting up the whole rig an option.

My head hurts now, not sure if I can think about this any more today.
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Old 04-06-2015, 08:18   #21
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Re: Recommended coax for triatic stay HAM antenna

I think Bill's idea is probably your most practical solution, if you must use your triatic. There will be higher coax losses than actually putting the tuner at the top of the mizzen, but even in the worst case probably not enough to make a practical difference most of the time.

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Old 04-06-2015, 08:44   #22
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Re: Recommended coax for triatic stay HAM antenna

Quote:
Originally Posted by SoonerSailor View Post
I think Bill's idea is probably your most practical solution, if you must use your triatic. There will be higher coax losses than actually putting the tuner at the top of the mizzen, but even in the worst case probably not enough to make a practical difference most of the time.

Chip


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Just to clarify, coax loss due to mismatch (high SWR) will be higher with the tuner near the radio than if located at the antenna. The difference can be significant especially if the antenna is not resonant which is typically the case when used on a wide range of marine frequencies.

Putting the tuner at the antenna eliminates all but attenuation loss because the radio and the coax are seeing a nominal 50 ohm match. Convenience dictates placing a tuner near the radio often but recognize that configuration serves primarily to make the transmitter 'happy" by masking the mismatch along the entire length of coax.

Placing a tuner at the radio end of the coax serves to 'fool' the radio into thinking it is transmitting into a matched antenna system.
The objective may not always be practicable but putting the tuner at the antenna is always preferable.
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Old 04-06-2015, 09:59   #23
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Re: Recommended coax for triatic stay HAM antenna

Just to clarify more, putting an UnUn at the mast top can mitigate the SWR mismatch between antenna and coax on desired bands such that SWR losses on those bands are reasonable, compared to the losses that would occur without the UnUn (which is an impedance transformer). You would of course still use the ATU down in the cabin, and want to place it such that the coax from ATU to UnUn is as shirt as practicable.

All of this is dependant on length of the actual antenna and the bands of interest.

In the end, a 23' whip on the stern with atu near the base would probably be the easiest effective solution.


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Old 04-06-2015, 13:31   #24
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Re: Recommended coax for triatic stay HAM antenna

Autumnbreeze,
Well, you really know how to ask a question without a single definitive answer...
But, I still think I can help...

I will come at this from TWO DIFFERENT SIDES....
First, is the way everyone else is looking at...
Second, will be what type of antenna do you require/desire for what freqs/distances....(which is my usual first step in antenna design, but on our sailboats, this is usually just an after-thought, as we just use what we got!)

1) So, up front....
a) Bill's advice here is as close as you're going to get to being definitive....(assuming you bite the bullet and buy an AH-4 tuner, which will tune all the HF bands, marine and ham, assuming you have a long enough antenna attached to it!)

b) And especially these pieces:
Quote:
Originally Posted by btrayfors View Post
This might sound wanky, but since you already have a tuner, why not try to load up the whole uninsulated rig and see what happens? Sometimes this works better than you'd think.

Just run GTO-15 from the tuner to the nearest bolt thru a chainplate, run a ground of some type (KISS? Copper strap to a bronze thru-hull? Radial ground wires?), and see how that goes. You may be surprised.
Quote:
Originally Posted by btrayfors View Post
Another option would be to forget the triatic and just use an insulated shroud, either on the mizzen or the main.

c) You should have a look at these threads here, which will give you some more info...

SSB antenna for a ketch.

SSB Antenna without a Backstay



d) I'm not familiar with the rig dimensions of your boat, but assuming the mizzen is at least 30' - 35' high, you do have some options other than loading up the whole rig...

I do think trying an "alternative backstay antenna", especially one off the mizzen (and even trying it off the main mast), and/or an "alternative sidestay antenna", are worth trying BEFORE you make any permanent decisions....

Although, Bill is correct that sometimes getting a ketch's HF antenna to work as well as a sloop's, is difficult....but, it sometimes does work!!
--- String up some wire,
--- use a good tuner (the AH-4 will work well with your IC-7200),
--- and run a decent RF antenna ground....
[note that the 2nd and 3rd things here, you're going to NEED to do anyway, so all you need to "experiment" with is where/how to run the antenna wire, and how it performs..]

If you haven't the time nor expertise to make effective comparisons of antenna performance over a period of weeks, etc....no worries....just have a go with one of Bill's suggestions/recommendations, and you'll be good-to-go....





2) Now the reason I haven't mentioned using the triadic rigging is multi-fold...(although it can be useful as a continuation of a shroud antenna, a triadic on its own isn't a good choice for most applications!)

a) It can make an acceptable 7mhz/8mhz NVIS antenna....and it "might" even work as a decent long-range antenna on SOME bands...
b) It's probably only about 20' - 24' long at best???
c) A ~ 45* sloping wire can have some odd angles of radiation...
d) Its short length will make it a very inefficient antenna on the lower bands (3.6mhz / 4mhz, etc.)....
e) If trying to feed it with coax/un-un, etc....this is going to be a very inefficient antenna!

Not knowing your exact rig dimensions, I cannot be absolute about the above statements, but I'm pretty darn sure!

If your desire is for "local" / "regional" comms on 7mhz / 8mhz, then attempting to feed the triadic (whether by mizzen-mounted tuner or current balun/un-un), would have merit....as a near ~ 1/4-wave wire, horizontal/sloping, at about 30' - 40' high is a good NVIS antenna for 40m...

And surprisingly, you may get lucky (again a lot of this depends on your rig dimensions and what bands you desire to work, at what distances), and you might find some good long-range performance....as a > 1/4-wave wire, sloping/horizontal, at about 30' - 50', can be a good long-range antenna on 20m, etc...

But most of these results of the triadic are difficult for me to pre-judge, as we'd need to know all of your rig dimensions, the exact angle of the triadic, it's exact height, etc...and even then your exact results are not guaranteed!
So, if your desire is for an antenna that will work well across most of the HF bands, be fairly predictable, easy for the tuner to find a match (meaning low tuner losses), have good low-angles of radiation for long-range work, etc. etc...then the triadic is usually not the best choice....




3) To sum up....
-- Take Bill's advice....try some of his ideas....
-- Try an "alt backstay" approach, or "alt. side-stay"...
-- Try to load up just a shroud...
-- Try to load the whole rig...
-- Read more...


I know I didn't give you a definitive answer....'cause there really isn't just one!
But, I do hope this helped..

Fair winds..

John
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Old 04-06-2015, 14:11   #25
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Re: Recommended coax for triatic stay HAM antenna

Quote:
Originally Posted by autumnbreeze27 View Post
I've got a IC-7200.

Does that mean I have to run control wires up the mast too? GRRRR
Is thus a vhf or hf / ssb install?

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Old 04-06-2015, 14:12   #26
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Re: Recommended coax for triatic stay HAM antenna

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Originally Posted by btrayfors View Post
autumnbreeze27,

Sorry to say, your basic plan is not workable
, i.e., to run coax from the tuner to the top of the mizzen mast and then connect to an insulated triatic. BIG WASTE OF EFFORT AND MONEY. Signal losses with such an antenna would be horrendous, no matter which coax you choose.

By the way, the antenna starts AT THE TUNER. All that coax running up the mizzen would be part of the antenna....and a very lossy part at that.

The question is not "which coax to run?". Rather, it should be, "what kind of antenna to rig?".

A much better plan is one like my friend, Scott, has on his 60' ketch. He insulated one of the shrouds for the mizzen and used that for the lower part of his antenna, then put a jumper between the top of that shroud and the insulated triatic stay.

This means that the whole shebang from the chainplates on the mizzen shroud to the top of the triatic is the actual antenna.

You could then install the tuner belowdecks and feed the chainplate.

This yields a MUCH more efficient multi-band antenna. Scott uses his for both ham and marine nets, with great success.

HF antennas on a ketch are quite difficult to rig, especially if there are permanent backstays on the main mast. Too much wire and too much interference. I have another very active ham friend on a smallish ketch who has that problem. No matter what he tries, his signal strength is always weaker than other similar sized boats with sloop rigs.

Bill
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Good advice.

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Old 04-06-2015, 14:56   #27
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Re: Recommended coax for triatic stay HAM antenna

FWIW:

Loading up the whole rig is what I have done on my two long term cruisers, and it has worked surprisingly well on bands from 80 metres to 10. On Insatiable II I feed the port shroud chainplate with a very short bit of GTO from the tuner (manual in this case). I've done it with the base of the mast grounded to the keel and without, and while it changes the tuner settings there was no perceptible alteration in performance.

Obviously your rig is different than my sloop/solent rig, but considering that it will cost you nothing to try the method a test seems to be a good idea. So, pick a convenient chainplate and hook it up for a trial. If it works well enough, then worry about tidying it up.

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Old 04-06-2015, 19:38   #28
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Re: Recommended coax for triatic stay HAM antenna

The distance between the masts is 21'. Doing some estimating using mizzen vs main sail dimensions I've calculated the triatic stay is around 27.5'

Plan right now is to insulate a upper mizzen shroud and the triatic, and not attach at the chainplate but above the insulator on the shroud (to avoid the other shroud)

Any thoughts? I was going to go to HRO tomorrow to get cable to jumper the below deck tuner to the shroud, then shroud to triatic.

Should I use the LDG or get the Icom tuner?
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Old 04-06-2015, 20:00   #29
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Re: Recommended coax for triatic stay HAM antenna

To be truthful I have not read every post here, but to the OP your original plan is flawed.

Your antenna will be too short even if you put a tuner on top of the mizzen, it will not work.

What you need is an "Inverted L" antenna.

IF your triatic stay is a load bearing stay, you need to buy a pair of insulators to put near either end. Then run another stainless wire, 1x19 or 7x19 from just ahead of the aft resistor down to about 3' off the deck and terminate with an eye. A line ties this line to a pad-eye on the deck or your toe rail.

Your tuner goes below deck just where the line ties off. Drill through the deck (do not use a metallic grommet) and pass the wire from the hot-point on the top of the tuner to just above the eye at the bottom of the riser.

From the hot point to the upper end of the Triatic is all antenna. is must be longer than 23 feet. There must be NO 90 degree bends in the antenna or feedwire.

The best wire is GTO15 or the type they use in the neon sign writing industry. 6000v minimum insulation.

This will look like your diagram.

Have a look in the ARRL handbook, or antenna handbook.

Next is ground-plane You must have a foil between the radio and the tuner and then from the tuner to the dynaplate or whatever is your grounding system

Good luck !
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Old 05-06-2015, 11:06   #30
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Re: Recommended coax for triatic stay HAM antenna

Autumnbreeze,
Well with the caveat that I've said before (and Bill wrote here as well), in your situation everything is going to be a compromise....
So, knowing this, here are some thoughts:

1) As I have written to you in the past, the LDG is not the tuner for this system....if you can afford it, get the AH-4...
No matter what antenna you end up with, the AH-4 is going to be what you will need, no avoiding that fact...
(and again, just 'cause the guys at HRO recommended the LDG, or anything else, doesn't mean they are correct!)



2) As for feeding the upper shroud and triadic (I think I understand what you're planning??), this is over-thinking / over-designing things a little bit....yes, it would work, but you seem to be avoiding the recommendations of others (myself, Bill, Chip, etc.) and instead are coming up with your own ideas (which IS a good thing) and asking for opinions on those....
So, as I have said before many times, almost anything metallic will work to some extent as an antenna....but I'd take some of the recommendations here as some of the better ideas, and only deviate from them if necessary, rather than discounting them out-of-hand...

If you don't want to mess with insulators, or they do not fit into your budget, then design an antenna that doesn't need/use them...
a) String up an "alt backstay" or "alt sidestay" or "rope tenna", etc....feed it with the AH-4, and you're done!!

b) Feed the mizzen rig from a shroud....see how it works...


Or, if you wish to complicate things:
c) You can run a GTO-15 wire up along a shroud, and then connect it to an insulated section of ringing (such as your planned upper shroud and/or triadic), and the ENTIRE run of GTO-15 and the insulated rigging IS your antenna...
As long as the shroud isn't grounded, there will be little effect from the GTO-15 wire being run up along the shroud....
YES, some of the transmit energy WILL couple into the shroud / rig, but even most of this will radiate...so this approach WILL work...


3) Forgive this next sentence...
As I wrote earlier, I think you originally got some rather poor advice from HRO and have been trying to dig out from that for the past few months....sorry about that, but that's what I see...

As for what to do?
a) Trade the LDG for the AH-4....yes, I know I've been saying this for months now...but that's what I still recommend!
And, install the AH-4 below decks, near the base of your antenna/shroud/etc...

b) Rig a wire to test various locations / set-ups...

c) Take Bill's advice/recommendations....

d) Read my earlier post, and take my advice / recommendations...
Recommended coax for triatic stay HAM antenna



Quote:
Originally Posted by autumnbreeze27 View Post
The distance between the masts is 21'. Doing some estimating using mizzen vs main sail dimensions I've calculated the triatic stay is around 27.5'

Plan right now is to insulate a upper mizzen shroud and the triatic, and not attach at the chainplate but above the insulator on the shroud (to avoid the other shroud)

Any thoughts? I was going to go to HRO tomorrow to get cable to jumper the below deck tuner to the shroud, then shroud to triatic.

Should I use the LDG or get the Icom tuner?



I hope this helps...

Fair winds..

John
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