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1-10 of 12 messages
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Antenna Question
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by GRANTLANK on January 20, 2008
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I am having a very hard time finding/deciding on an antenna to buy. I am planning on an Icom IC-706MKIIG for my rig. I need an antenna that covers 6m/2m/70cm. I will worry about the HF later when I am licensed to use it. I would prefer some kind of omnidirectional antenna like a vertical. The only problem with the verticals that I have found is they require radials which i do not have room for. I read that a 1/2 wave does not require radials, but I have been unable to find one. I also gave some thought to making a dipole, but don't know about making a tri-bander. Could anyone offer and comments, suggestions, help, etc.? What kinds of antennas are you all using?? What do you recommend?
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RE: Antenna Question
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by N5WD on January 20, 2008
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The IC-706 MKIIg is a very nice radio, covering the HF bands, plus 6m, 2m and 440 MHz. You'll need more than one antenna to cover all of these bands:
Since you have HF voice priveleges on 10m, at the very least I'd suggest you put up something there to give HF a try. It often is a great incentive to help people want to upgrade! For 10m, you could put up a dipole, either horizontally or vertically, or even put up a ground plane. Many folks have taken CB ground planes and retuned them up in frequency to use on 10m with good results.
For 6m, if you are going to use SSB down in the weak-signal portion of the band, a horizontally polarized antenna would be a good choice, especially for local communications via ground wave. An omnidirectional like a PAR OAG-50 or something similar would do well, and if you can mount a small 3-element yagi up on a TV mast, that would give yo ua bit more gain.
If you're planning on using the upper portion of the 6m band for FM work, it's pretty much all vertically polarized there. A 1/4 wave ground plane, or a vertical dipole would be a good choice.
The same general advice goes for 2m and 440 as well - horizontal down in the lower portion in the weak-signal band... vertically polarized in the upper FM portion.
There ARE multi-band vertical antennas from Diamond and Comet that will cover more than one of the FM bands. Those work well.
Sorry I couldn't be more specific with the advice - it's just that a lot depends on what you intend to do with the radio, and what modes you plan on working.
Congrats on the new license! 27 of my engineering students just got their license this week, as well, so I understand how confusing this can all be when you're trying to make a lot of decisions all at one time.
73 Wayne N5WD
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RE: Antenna Question
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by GRANTLANK on January 20, 2008
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Thanks for the help! I really appreciate people in this forum providing such good help and advice. I agree with you on the 10m. I would like to have the capability to transmit on 10m. I believe I can tackle making a dipole 10 m. For the UHF/VHF I have looked at the 6m/2m/70cm tri-band antennas, but don't have the room for ground radials. I guess my two options are a beam or a dipole. I would like to have omnidirection capability for local communication, but would sacrifice that to get an antenna that doesn't require radials. I guess my question would be could I make a wire dipole that would work on 6m/2m/70cm. Would this work if I connected it to an antenna tuner? Would I be better of with a beam? I would like to have all my UHF/VHF on 1 antenna.
Thanks in advance for the help,
Grant
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RE: Antenna Question
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by N5WD on January 21, 2008
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> I have looked at the 6m/2m/70cm tri-band antennas, but don't have the room for ground radials.
Look for some of the "base station" antennas that don't require radials... for example, the Comet GP-15 (see http://www.cometantenna.com/products.php?CatID=1&famID=5&childID=2) has radials that look like they're fairly short. There are several folks who've reviewed the GP-15 here on EHam.net - perhaps one of them could tell you how long the radials measure. I use one of their base station antennas for 2m/440/1.2GHz and the radials on that are about 12", IIRC.
This type of antenna would work well as a non-directional (or omnidirectional, if you will) antenna. If you need more gain in a particular direction, then a small beam would be the next choice.
> Would I be better of with a beam?
That depends entirely on who (or what, as in the case of a repeater) you're trying to talk to and how good that signal is. Omnidirectionals simplify life, but only if you can hear 'em.
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RE: Antenna Question
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by AE1X on January 21, 2008
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Thanks for the help! I really appreciate people in this forum providing such good help and advice. I agree with you on the 10m. I would like to have the capability to transmit on 10m. I believe I can tackle making a dipole 10 m. For the UHF/VHF I have looked at the 6m/2m/70cm tri-band antennas, but don't have the room for ground radials. I guess my two options are a beam or a dipole. I would like to have omnidirection capability for local communication, but would sacrifice that to get an antenna that doesn't require radials. I guess my question would be could I make a wire dipole that would work on 6m/2m/70cm. Would this work if I connected it to an antenna tuner? Would I be better of with a beam? I would like to have all my UHF/VHF on 1 antenna.
Thanks in advance for the help,
Grant
Grant,
VHF/UHF requires a great deal of attention to detail. The other commentors have told you about what you need to consider when choosing your polarization. All Weak Signal work is done with horizontal antennas and all FM and digital work is done using verticals.
Concerning Multi-Band antennas, you will find the VHF UHF antennas do not in general require radials.
Running any antenna with a tuner on VHF/UHF is not a really practical idea. I have seen tuners for 6m and 2m, but not the higher bands. You will find that the losses in the tuner and the coaxial cable due to the mismatch will render this idea impractical.
There is one antenna type that I have not seen mentioned here and that is the discone. Radio Shack and others have this type of antenna available that will cover 6, 2, 220, 70cm, 33cm, and even 1.2GHz. The antenna is not large. I have one that I purchased on eBay for $28 on a TV mast at my home attached to the chimney that works fine. It behaves as 1/4wave vertical on all bands for which it will work. Mine works on 2m and 70cm and I know it will work on 222MHz. I just have to take a few minutes to run my tests. It will run on the high bands as well, but I don't have gear for them at this time to run any tests with.
One additional type of antenna that you could construct yourself might be of interest. Look into a J-Pole antenna. You can construct these out of a lot of different materials and they work. In fact, I've seen at least one design that will work on 2m and 70cm. See the literature for details.
Good Luck,
Ken - AE1X
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RE: Antenna Question
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by GRANTLANK on January 21, 2008
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Thanks so much, you guys have been such a big help. I hope to have my station up within the next few weeks and thanks to your help I feel comfortable purchasing the correct antenna!
Thanks again for the help,
Grant
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RE: Antenna Question
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by ONAIR on January 21, 2008
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Get a roll of good coaxial cable, and make your own homebrew bazooka coax vertical dipoles for 10m, 6m, 2m, and 440. Simple and inexpensive to make, no radials needed, and resonant on each band without a tuner!
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RE: Antenna Question
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by GRANTLANK on January 22, 2008
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I got my call today! KJ4BNF
That was fast! I just took my test on Saturday.
I guess I'll have to make a new user on this site so I can use my call as the username.
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RE: Antenna Question
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by KJ4BNF on January 29, 2008
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Ok on my rig (Icom IC-706MKIIG) there are two connectors for antennas. One for HF/6M the other for 2M/70CM. I have one antenna that I want to use for 6M/2M/70CM. How can I set this up to where I have one antenna running off of two connectors on my radio. I was thinking about a combiner to combine the two antenna ports into one feed-line, but the combiners say they are for receive only not transmit. Will this still work? I am planning on adding a HF antenna soon.
73
Thanks,
Grant
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RE: Antenna Question
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by K9WJL on February 1, 2008
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Congrats on your license. I would use two jumpers and a selector switch. Connect the jumpers from the antenna ports on the '706 to the switched side and your feedline to the other end. I use Daiwa CS-201 switches here, and their good quality and reasonable in price.
73,
Bill K9WJL
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