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Old 15-11-2006, 17:23   #1
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NEED HELP on SSB installation and tuning

Hi Everyone

I am not sure, but think I may need some help with my SSB installation and tuning. I have an ICOM M-700 SSB and am using a new LDG AT-200Pro tuner. The SSB and tuner are both grounded via copper foil to a through hull and copper foil run through the bilge.

My antenna is my topping lift. It is rope from the masthead to about a few feet out, then wire to the end of the boom where I have two blocks...so it is completely insulated. Must be about 40ft long. The LDG tuner has a coax cable connection to the antenna, I have run 15ft of RG-8U coax to the topping lift and connected the center conductor of the coax to the topping lift wire. The outer braid is grounded to the boom...the mast is grounded to the ships dynaplate.

This set up seems to be working well. I am in the FL keys and can hear boats from Bermuda and way down in the carib, all very clearly. I have been heard in GA (8MHz), but have really not had much opportunity to test this set up.

I have 3 Q's:

1) the tuner seems to not be able to tune in the 2MHz band. Is there something I can do...grounding, a different antenna set up to rectify this...or is this simply a fact of the physics of my set up. Note that the tuner has no trouble at all on other bands and SWR is 1 or very low.

2) I realize this is not an ideal set for an antenna...but I like it for now...very convenient for me..for right now. So...should I be doing something different with the outer braid of the coax in this situation?

3) Would a 1:1 current balun help at all?

Thank you all, I really would appreciate any and all input and any diversity of opinion.

My best to all.

John
s/v Invictus
Hood 38
lying FL keys
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Old 15-11-2006, 18:01   #2
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You're end feeding the 40' topping lift? Very impressive tuner. If it works fine on all other bands, it sounds like you have to get the antenna cut closer to a wavelength fraction for the tuner to do it's job at 160 meters.

Rick in Florida
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Old 15-11-2006, 18:23   #3
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John, I am not familiar with your tuner but almost all that I have installed never used coax to connect to the antenna. They all used GTO high voltage cable that looks very much like coax. It ONLY uses the inner wire to connect at both ends and the shielding is stripped away at the connections.
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Old 15-11-2006, 20:02   #4
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Guys, thanks for the replies...I really would appreciate some help with this. LDG is a very well respected tuner company in the HAM world...I am not a HAM...just did some research. I do realize that all the ICOM marine tuners are single wire and thus GTO wire to the antenna. One thing I liked about the LDG was that it was coax fed to the antenna...thus you could have the tuner sitting on top of the radio and run any length of coax to your antenna.

At any rate....Rick...you wrote 'impressive tuner'...why? Is there some challenge doing what I did?? I thought most set ups on sailboats were essentially just what I did...end feed a long wire?? I probably could adjust the length of the wire....but since the rig is 55ft off the water and 45 off the deck....doubt I can add any more significant length to help in the 2MHz range.

Most product lit says you need only 23ft of wire for an antenna and I have 40....I am wondering why I am not getting 2MHz performance....but given to think that is it usually poor in this range at any rate? No?

What about my antenna set up....the 40ft wire, coax center conductor fed, with the outer braid grounded on the boom. ANy issues? Any better set up (I know using an insulated backstay is the more permanent solution...but for now...the topping lift).

THANKS....any advice and all comments appreciated.

John
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Old 16-11-2006, 08:36   #5
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John,

I see a couple of problems with the setup you describe.

First, you must realize that the coax you are using to feed the base of the topping-lift antenna IS A RADIATING PART OF THE ANTENNA. And, you have grounded the shield side, via the boom/gooseneck/mast-to-ground connection.

Second, the tuner you are using with a coax feed is meant to match a BALANCED antenna, not a random-length end-fed antenna. It's fine for dipoles, beams, G5RVs, Carolina Windoms, and such antennas, but not for end-fed random-length wires.

You can buy a balun designed to match this type of tuner to a random wire antenna. LDG makes one (I have one)...it's their BA-1 4:1 Balun. However, this probably won't help much.

I think you'd be best advised to abandon the idea of a topping-lift antenna (because of the difficulty of feeding it properly from the lower end), and consider other low-cost and more robust alternatives.

One possibility might be to rig an "alternative backstay" antenna, hoisted with a spare halyard and with the lower end tied off to one side of the pushpit. I've used one of these for over 16 years now, with excellent results. You want to get the tuner as close under the deck as you can, and run a short length of GTO-15 wire or equivalent from the tuner to the base of the antenna.

I've used insulated s/s lifeline for my "alternative backstay" antenna, because of it's indestructible properties in the saltwater environment. Obviously, you can use any type wire for this purpose, but be sure to consider strength and corrosion-resistance properties.

Then, you need to consider an effective groundplane/counterpoise system. The copper foil you now have in the bilge might be sufficient. Radials could be added if necessary.

Remember that the radiating part of the antenna begins at the antenna connection on the tuner, so you want to get it as close to the antenna base as you can.

The LDG tuner you have is a good one by all reports. I would contact LDG (they're very responsive) and ask them what is the best balun to use in your setup to feed a random-length end-fed wire antenna, using this tuner. They'll steer you right.

LDG Electronics
1445 Parran Rd.
St. Leonard, MD 20685 USA
(410) 586-2177
www.ldgelectronics.com

Good luck,

Bill
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Old 16-11-2006, 09:16   #6
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Bill!

Thank you for taking the time to reply, I appreciate your knowledgable input. I have emailed back and forth with LDG and they have been helpful...but really did not have a good idea of what to tell me. Their input was that the tuner was perfectly good with an end fed long wire, but I should use a balun. They recommended their 1:1 current balun. I do plan to get one...but have also been told that it may not make too much of a difference.

By all accounts, the set up seems to be working well (just no tuning on 2MHz). I had a very clear conversation with a boat in GA this am in the 8MHz band. Seems to tune quickly and remembers the tune...but..again..not in the 2MHz band.

I know I need to do a more permanent installation...I like your idea and will try that. I am sure that will work great.

One question.....using a balun with this end fed long wire, you do connect to a ground (presumably, this is from the coax outer braid. Someone else online told me that I should ground the coax outer braid if I am not using a balun. I am a little confused on this point. Should I not be grounding the outer braid at all (if I do not use a balun)?? Does it matter?

If I were to run GTO wire from this tuner....how would I do that? The tuner output is a coax PL259 connection...would I simply run a very short piece of coax and then attach GTO wire to the center conductor? And this would be better than what I am doing now?

I do have a ground plane set up and would like to go over it with you: I am [cheaply] using copper flashing I got at Home Depot. I have it cut to 3 inch wide lengths. I have one strip run from the tuner ground to a through hull and then connected to a long run of this in the bilge. I have another length run from the radio ground lug to the same through hull and on to connect to the same long run in the bilge. Good or no good? Any changes to make?

Thanks for all, I appreciate your help.

Best

John
s/v Invictus
lying FL keys
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Old 16-11-2006, 09:44   #7
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John,

Don't be misled by your ability to make contacts. A ham who knows what he's doing can, quite literally, make contacts by loading up his bedsprings!

Again, I'd abandon the topping lift idea; it's just too problematic and too lossy.

With regard to the alternate backstay idea -- very simple to rig and very effective -- here's how you do it.

1. Find a suitable length of wire. For trial purposes, and until you're a "believer", I'd just use anything handy.

2. Overall length isn't that important, but to optimise the lower frequencies (e.g., 2-8 MHz), the longer the better. Why do you care about the 2MHz frequencies, anyway? There's nothing there....very little use these days.

3. Decide where the lower end will be. The forward end of the pushpit is usually ideal -- either port or starboard as you like -- because it's clear of the end of the boom.

4. Hoist the (temporary) antenna with a spare halyard, and secure the lower end to the pushpit. You can use antenna insulators if you want, or short lengths of Dacron will work fine, too.

5. Find a home for the LDG tuner beneath the deck and closest to the antenna base.

6. You will need some sort of current balun. 1:1 may be alright, but I think 4:1 would be better. LDG is OK. RadioWorks is OK. Others, too.

7. Connect the LDG tuner to the radio using RG-8X coax. Any length will do; it's not critical. You can locate the tuner as far from the radio as necessary.

8. To avoid stray RF, it's a good idea to put some ferrite beads around the coax at each end, i.e., closest to the tuner and closest to the radio.

9. Connect the coax OUTPUT from the LDG tuner to the balun, using RG-8X coax.

10. Connect a length of GTO-15 wire from the antenna side of the balun OUTPUT, through the deck, to the base of the antenna.

11. Connect the RF ground system (your copper foil, etc.) to the OUTPUT ground side of the balun.

Think of it this way: you're feeding the signal from your radio through the coax to the tuner and through the short coax to the balun. At the balun, you're splitting the signal, one part to the antenna, the other part to ground.

By the way, you can see my "alternate backstay" antenna here:
http://gallery.wdsg.com/Maine-Trip-2...ckland1?full=1

It's on the starboard side...you can see two white lines, one is the nylon line from the little black insulator to the pushpit, the other is the GTO-15 wire which feeds the antenna.

Despite all they hype and the nonsense about grounding plates and 3" wide copper, grounding to keel, etc. -- and it is just plain nonsense from an RF engineer's perspective -- what works like gangbusters is to have a counterpoise consisting of radials (insulated wires, either tuned or random length...the more the merrier) or other structures which can serve as an effective counterpoise. I use my aluminum toerails and pushpit/lifelines/pulpit complex as a counterpoise.

Since you already have the copper foil and the thru-hull connection (great DC ground and good for pumping RF into the sea), try it first. You can always experiment and add radials later on if needed.

Gotta run...

Good luck,

Bill
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Old 16-11-2006, 10:33   #8
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Bill-
I'm wondering if the topping lift isn't really isolated. Could the four feet of rope at the top of it, saturated with salt air and moisture, maybe be acting as a high resistance and capacitive connection right back to the ground (the mast, connecting back to the boom) and making this into some type of oddball loop antenna?
Aside from the issues of coax and balanced lines...I'm just thinking that even as an end-fed wire, that topping lift isn't really "clean", even if the rope at top was pristine it is still running next the the mast--the ground.

Dunno, never investigated the RF properties of a piece of damp line very closely.<G> Just questioning it.
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Old 16-11-2006, 11:54   #9
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Bill,

Terrific advice. Years ago I used an end feed on a long wire with a ground that wasn't quite as good as I thought it was. I still remember the shock and surprise of RF burns on my hands when I fired 'er up.

With an end feed it's always best to have the high current point high, as opposed to feeding the low end.

I love Bill's idea of turning the life lines into a counterpoise, as it makes perfect sense.

Here are some other links that might prove useful. I have to mention that I had Bill's site on this list as well.

http://www.icomamerica.com/marine/ssb_book.asp

http://radioworks.com/2006%20product%20manual.pdf

http://groups.google.com/group/rec.b...9b9e4d285b55f1
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Old 16-11-2006, 12:55   #10
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Guys - this is really great advice and I hope an interesting thread to others.

I will try GTO wire from the tuner to the antenna soon. Do need to get a balun. Do I really get that much loss from 15ft of RG-8U coax??

Thanks again, my best to all. Please keep the comments coming. Maybe we can get a test call going?

John
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Old 16-11-2006, 12:57   #11
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No, there's little loss at HF with RG-8U. SWR is more of a consideration.

Rick in Florida
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Old 16-11-2006, 13:00   #12
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Rick - thanks - that is helpful...I am just beginning to understand the difference. Good info.
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Old 16-11-2006, 13:01   #13
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John,

No, the loss doesn't come from the RG-8U itself. RG-8X is just smaller and more convenient to work with, and is relatively low loss at HF frequencies.

The loss in your current setup comes from the fact that what you essentially have is a RADIATING portion of the antenna encapsulated in a GROUNDED shield (running up from the tuner and, presumably, along the boom to the bottom end of the topping lift). And, you have multiple grounding points...a no-no.

Bill
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Old 16-11-2006, 16:25   #14
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Bill

Thanks for the input. I think we are almost there. I can implement your direct wire solution and take off the coax. No problem...did a little experimenting...I have 15 ft of 14g electrical wire aboard...connected that to the center conductor of a short length of coax connected to the tuner output. Seems to tune to 2MHz now. Of course...no idea how I sound out there yet.

Big question....the ground. WOuld you let me know what you mean by my having too many grounds??? I thought copper foil was a good thing...and lots of it. Would you let me know how I can adjust my copper foil grounding at this point to make it an effective ground? Should I just tie the SSB and tuner grounds to the through hull? Or let the copper strips run through the bilge and forget the through hull?

Please advise. I think we are almost there.

Thanks!
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Old 16-11-2006, 18:01   #15
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I don't have any first hand experience with this product but have heard some good second hand reports. It looks to be a great alternative to an insulated backstay and is very easy to install.

http://gamelectronicsinc.com/ssb.htm
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