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Old 11-09-2007, 22:06   #1
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Dipole Questions Re Placement / 1612C Tuner

Hello

I am installing an Icom 718. I have read all the posts I can find here on antennas and I have bought the materials per the Serious Ham SSB Setup on the cheap. However, I still have questions:

1. Is an inverted V dipole as efficient as a straight up dipole?

2. Does anyone have any pictures of where they installed their inverted V? Should I attach my V to the stern? To the bow? From the stern to the bow? My other concern is where to put the hole in the deck for the coax so that it is completely out of the way

3. How long can the coax be before you just loose too much signal?

4. I found a C Auto tuner 1612C by Sea. The unit is used, but the price is only 140.00 The man says it can be used to only tune marine frequencies and it cannot be used to tune ham frequencies. However. I have looked at the Sea 1612C on the Sea website -- the unit new is 900+. I am thinking this cannot possibly be the same unit. The PDF file says it tunes from 1.3 -- 30Mhz. Does that range cover the HF ham frequencies? (please excuse the ignorance on the frequency vs MHz. I never have been able the get that stuff straight in my head. Would this be a good unit to get for my 718?

Thanks

Michael
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Old 11-09-2007, 23:02   #2
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I've got no personal experience with either of these (the Icom ham xceiver or the Sea tuner), but looking at the on-line data:

The Icom seems to be a good ham transceiver, and there are some good reviews out there. It ought to do the job for your ham contacts.

The Sea is a broadband unit, and should tune the HF ham bands. These ham bands are from 3.5 MHz (80 Meter) to 28MHz (10 Meter), but on a boat you will probably be using 7 MHz (40M), 14 MHz (20M) and 21 MHz (15M). To use the ham bands you do need a ham license, and the fact that you are asking about frequencies makes me guess that you don't have your ticket yet.

The Sea unit is designed to tune an end-fed wire, not a coaxial-fed dipole. The specs are unclear to me about the tuning range, since they mention both a 9-ft whip and a 23-75 ft usable antenna length. We really need someone who has some experience with this unit to chime in here, as various tuners have strengths and weaknesses that don't show up on the spec sheets.

If you do some searching here, you will find discussions of the various antenna configurations, and while the dipoles and inverted-V's are nice at anchor, I like my insulated backstay (with antenna tuner) for use while underway. The simplest thing to do would be to haul up a sloping dipole, cut for the 20 Meter ham band -- one end near the top of the mast, and the other end at the bow or stern. The antenna will be about 33 ft long. You shouldn't need a tuner, once you've got it trimmed to length, and 20M is probably the most useful band to start with.

I expect that you will get some good advice here from people with experience with these specific units, but I figured I'd start the ball rolling.
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Old 11-09-2007, 23:07   #3
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Thanks for the response Paul! As embarassed as I am to admit, I do have my starting ticket (at least in the VHF!) , but I do not have my General yet. So far, I have yet to get the frequencies in the HF area straight.

M
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Old 11-09-2007, 23:32   #4
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Thanks for the response Paul! As embarassed as I am to admit, I do have my starting ticket (at least in the VHF!) , but I do not have my General yet. So far, I have yet to get the frequencies in the HF area straight.
M
I sometimes forget how much of this is "non-obvious", having been immersed in it for the past 40 years. Do get the General ticket, HF operation is a lot of fun. Now that it's no-code, it's that much easier.

How do you plan to use your radio? There are good reasons to get a marine-band rig, but they are $$$ and usually not as easy to use for amateur stuff. The general-coverage receiver in the ham rig can be used to get weatherfax, and you can use winlink for email, so the ham-only rig still lets you do most of what you might want.
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Old 13-09-2007, 18:10   #5
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Does anyone have advice for Mike re his Icom 718 and SEA 1612C tuner? I jumped in with some generic thoughts, but I was hoping someone with actual experience would be heard from.
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Old 13-09-2007, 20:01   #6
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Paul

In answer to your question, I plan to use my radio for general ham operation, and for listening to the marine bands. I suppose in an emergency if I did not have a type excepted receiver, I would use it to transmit. I really do not want to drop more money into a channelized marine receiver like the 802 right now given all the other projects I have going -- I think the 718 will get me by just fine for a while so that I can learn the TX and RX frequencies. I am on hamtestonline again going for my General and I will be glad when I have that ticket. I actually passed the General last year, but I did not have the code done then so now I have to take the exam over. I am also installing an R75 simply because the receiver is MUCH better than the 718. Yes, the 718 can transmit and receive from .1 to 30Mhz since D53, 54, and 55 are gone. Please, no grief.

As far as the 1612C tuner, I finally got a hold of the owner and this is the same unit that Sea sells for 900+ dollars. Why it is selling used for only 140$ is beyond me. He says he has checked it thoroughly and it will tune automatically from 1.3/2.0 all the way up to 30. The exception is that he says it will not tune the 10 meter band. I am not sure how much of a ham loss that band will be, but I am willing to accept the loss for the frequencies it can tune.

I think at this point I have read nearly every post on this board and on SSCA about antennas and tuning. This topic has been discussed! Over and over again! Ad nauseum! Sadly, I am still confused as to just where the antenna is to be placed. From all the different posts I have read, it must not be close to the shrouds, the legs of the V should be far apart, and there is even more fine tuning to do with an SRW meter once the length has been established. While the sifting through alll the posts is annoying as all get up, I will keep re-reading the posts until i get the required information firmly in my head. I still could use some photographs of a set up that works.
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Old 13-09-2007, 20:59   #7
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Mike,

It sounds like you are considering an inverted-V antenna, and since this is a balanced-feed antenna I'm pretty sure that the SEA tuner won't work with it (unless you have a high-voltage balun and an extremely low-loss feedline). I hope someone who knows will step in here...

Almost all of the advice given on this site is valuable, but let me add some of my own:

With the SEA tuner (or an Icom AT-130, which I *am* familiar with), your simplest antenna will be an insulated backstay, or a wire hauled up in a similar configuration.

An advantage of dipoles is that they can be cut to frequency, and will work efficiently without the need for a tuner. You can make a multi-band dipole, but on a typical boat installation, I expect that there will be significant trial-and-error to get it working.

Any HF antenna on a sailboat is going to be a compromise. My first priority is that the antenna not endanger my ability to sail the boat. It has to stay out of the way. If you are only going to operate while parked, this is not as big a deal, but I sure would want to be able to use the rig while underway.

Given the compromises, you shouldn't be too concerned about getting it *exactly* right. You can't. Just put something up that is reasonable, and enjoy it. You can fine-tune later if you want to, but in the meantime you will be making contacts. Most coupling issues will be frequency-specific, so just tune to a different frequency (if practical).

If you are using end-fed antennas (not dipoles), your ground system is at least as important as the antenna. Even so, there are plenty of ways to get an adequate ground. Pick something that is convenient for you. I don't believe that Dynaplates are any better than a similar-size block of bronze, and a through-hull is probably nearly as good.

Not strictly antenna-related, but beware of RF noise generated by on-board electronics. This is pretty easy to identify, but not always so easy to cure.

Bottom-line: Don't stress about it. You can struggle for years over that last 2dB, and it probably isn't worth it (unless you enjoy that kind of thing).
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Old 14-09-2007, 08:33   #8
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"vee" ant

These are used for a fixed frequency & would normally not be the choice for a boat unless you wanted one fixed frequency for some reason. They will not work with a tuner unit/matching unit. Long wire or whip is your option.

Regards Bill Goodward
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Old 14-09-2007, 10:11   #9
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He says he has checked it thoroughly and it will tune automatically from 1.3/2.0 all the way up to 30. The exception is that he says it will not tune the 10 meter band.
That sounds odd to me. The 10 meter band is 28.0 - 29.7 mhz. If it "will not tune the 10 meter band", then it will not tune "all the way up to 30".
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Old 14-09-2007, 12:45   #10
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I still have memories of RF burns when feeding an end fed, random length antenna. Not a pleasant experience.

I would think a vertical would be perfect on a boat. How about loading into the mast?
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Old 14-09-2007, 13:47   #11
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It's not installed on a boat, but I have to mention that I have a dipole that I cut to a 20 meter frequency. I've set it up as an inverted V anchored from the top of a flagpole and it worked great, I set it up with 3 anchor points in 3 trees and it worked great. I also tune it to any frequency between 40m to 10m with an MFJ manual versa tuner(they look complicated, but honestly, it's just a matter of fiddling with the knobs until your swr meter gets as low as you can get it.)

I've never used a random wire, except to recieve with, but I hear some good experiences with those. Honestly, anything is better than nothing, just get something up, see how it works and then change if necessary. If it were me, I'd just lose the auto-tuner. I've never heard of anything but trouble with those (a friend had one kill his transciever). Sell it to break even or even for a bit of profit and get a manual tuner. A tiny bit of extra work, but generally, once you find the settings for the bands you use it's just a couple of extra knob twists whenever you change bands. I've got a chart next to my radio of the settings for different bands.

Again, just my opinion, others will probably disagree with me and feel free to ignore this. In the end, it's all up to you, part of the great thing about both Ham radio and Cruising is that there is no one right way to do anything.
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Old 14-09-2007, 18:36   #12
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If it were me, I'd just lose the auto-tuner. I've never heard of anything but trouble with those (a friend had one kill his transciever). Sell it to break even or even for a bit of profit and get a manual tuner. A tiny bit of extra work, but generally, once you find the settings for the bands you use it's just a couple of extra knob twists whenever you change bands. I've got a chart next to my radio of the settings for different bands.
I have a manual tuner for my home ham station, and this is exactly how I use it. It works fine. The boat installation was my first experience with an autotuner, but i really appreciate having it. It is fast, convenient, and gives me excellent results (matching to my insulated backstay).

At home, I kind of enjoy fiddling with things. On the boat, my radio is a tool, and I just want it to work. The autotuner does it's magic and I love it. Especially with the computer controlling the radio for Pactor, not having to also mess with a manual tuner is an advantage for me. Note that I'm talking about convenience and simplicity, not functionality. A manual tuner will work fine and cost less then an autotuner.
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Old 06-06-2008, 10:13   #13
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looking for sea 1612c

Is this tuner still available? I have an sea 222 that I need a tuner for.


Quote:
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Hello

I am installing an Icom 718. I have read all the posts I can find here on antennas and I have bought the materials per the Serious Ham SSB Setup on the cheap. However, I still have questions:

1. Is an inverted V dipole as efficient as a straight up dipole?

2. Does anyone have any pictures of where they installed their inverted V? Should I attach my V to the stern? To the bow? From the stern to the bow? My other concern is where to put the hole in the deck for the coax so that it is completely out of the way

3. How long can the coax be before you just loose too much signal?

4. I found a C Auto tuner 1612C by Sea. The unit is used, but the price is only 140.00 The man says it can be used to only tune marine frequencies and it cannot be used to tune ham frequencies. However. I have looked at the Sea 1612C on the Sea website -- the unit new is 900+. I am thinking this cannot possibly be the same unit. The PDF file says it tunes from 1.3 -- 30Mhz. Does that range cover the HF ham frequencies? (please excuse the ignorance on the frequency vs MHz. I never have been able the get that stuff straight in my head. Would this be a good unit to get for my 718?

Thanks

Michael
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Old 06-06-2008, 10:14   #14
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is this tuner still available? I have an SEA 222 that I need a tuner for....
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Old 28-11-2011, 22:15   #15
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Re: Dipole Questions Re Placement / 1612C Tuner

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That sounds odd to me. The 10 meter band is 28.0 - 29.7 mhz. If it "will not tune the 10 meter band", then it will not tune "all the way up to 30".

The ability of the SEA1612C to tune on high frequencies is determined by the lenght of the antenna wire used, also if something other than 4 inch copper straps are used for goundring then the length of that wire should be a considerations also. The recommended 23 to 75 feet wire for the antenna are only guide lines and you might have to find the right length that will work for you installation.
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