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W2ABU
09-09-2006, 03:09 AM
Ok boys and girls, I need some feedback. I am looking for some input on what you think is a good dipole for 40 and 80 meters.

Homebrew or commercial, what do you think?

I have plenty of space here at the QTH for a full length one.

Thanks!!

Steve

WB7DMX
09-09-2006, 03:43 AM
buy the large G5RV #add a ant tunner and work all the bands, from 160 to 6 meters,
or build a long dipol, add a ant tunner and work all bands.
or build a dipole for each band feed them together with one coax, and work all bands.

W4HWD
09-09-2006, 04:34 AM
If you have the room, I would not go with the G5RV...I would build a half-wave 80M dipole and feed it with open wire. You will get outstanding performance on both 80 and 40 with such an arrangement (off just one antenna). A G5RV is a severe compromise on any band other than 20M...you can do better since you have the room.

WA9CWX
09-09-2006, 05:34 AM
Dipoles do not require a degree in brain surgery.

If you are handicaped, buy commercial.

If NOT, then build your own.

If you ONLY want 40 and a good portion of 80, and NO tuner, then build what is called a 'fan' dipole.
That is, one coax, and two dipoles, try to keep them apart from eachother, they will work, however, no matter HOW you run them.

If you are willing to use a tuner able to tune parallel line, then build a dipole of ANY length, but preferably at least 1/2 #wave on the lowest frequency, and feed it with open or ladder line.

Under NO cicumstances at normal height, or with any expectations of special patterns , etc, do you need ANYTHING at the feedpoint. Not a balun, not a coil, not a magic wand, nothing but feedline, an insulator, a support cable, and the antenna wire. #Period.

IF you solder the connections, keep the soldered part away from the flex/stress point of the wire.
Basicly, try to keep the flex point a GRADUAL one or two inch transition to the insulator, with a wrap of wire, and any solder point not right where the wire will move with the wind.

Try to keep the whole thing up high, and away from 'things'....but don't agonize over it, it will work WHEREVER it is, and work quite well.

W5DXP
09-09-2006, 01:50 PM
Quote[/b] (n2mai @ Sep. 08 2006,21:09)]I am looking for some input on what you think is a good dipole for 40 and 80 meters.
http://www.qsl.net/w5dxp/notuner.htm works for me.

W8JI
09-09-2006, 02:08 PM
Quote[/b] (n2mai @ Sep. 08 2006,20:09)]Ok boys and girls, I need some feedback. #I am looking for some input on what you think is a good dipole for 40 and 80 meters. #

Homebrew or commercial, what do you think?

I have plenty of space here at the QTH for a full length one.

Thanks!!

Steve
http://www.w8ji.com/g5rv_facts.htm

The truth about G5RV antennas.

73 Tom

AG3Y
09-09-2006, 02:29 PM
Putting on my O.F. Curmudgion hat ;

Back when I was a kid, there was no such thing as commercial dipoles. Everyone built their own, and everyone was able to fill a logbook with contacts.

If you have the room for them, as you say you do, put up a single dipole for each band, and feed it with an individual run of coax. You can either get a multi antenna switch, or fashion a "patch panel" to hook the proper antenna to the rig at the proper time.

Remember, a 40 meter antenna can be used for 15 as well, but since the bands above 20 are pretty dead a lot of the time, I wouldn't waste too much time lurking around up there. There's plenty of action on 20 and below to keep you interested.

You will get the best performance for the buck with single-band dipoles fed with coax. No tuners, No baluns, No messing around.

My O.F. Curmudgion hat is back on the hook now!

73, Jim

KC9GUZ
09-09-2006, 02:57 PM
80 meter doublet fed with ladder line run to a tuner.. Works like a champ!!!!http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

NE6AO
09-09-2006, 04:41 PM
Quote[/b] (wb7dmx @ Sep. 08 2006,20:43)]buy the large G5RV #add a ant tunner and work all the bands, from 160 to 6 meters,
or build a long dipol, add a ant tunner and work all bands.
or build a dipole for each band feed them together with one coax, and work all bands.
Ive read a lot of kurt sterba and he gave an excellent talk on the g5rv and a lot of loss is there if you go to other than the standard band its cut for ,notm to say that it wont work ,but if you want a good comprimise a extended double zepp cut for 80 and ladder line will work well for all hf not very good above17 mtrs. the full wave loop in the handbook and also the arrl ant book worked very well for me ,I made my own ladder line at 1 inch spaceing for an impedence of 200 ohms,again from the ant hand book.I worked all hf with it on my own homebrew lowpass tuner coil20 in long,2.5 dia apprx30 turns 12 awg copper house wire with a t connected capacitor in middle of coil and clip leads on the ends of the coil short out turns as nesscessary and use a 365 pf tuning capacitor you may need a little more capacitance. BUT GET THE ANTENNA HAND BOOK ,the final answers were usually found in the book ,73'sNE6AO

K5RCD
09-09-2006, 05:14 PM
Quote[/b] (n2mai @ Sep. 08 2006,22:09)]I have plenty of space here at the QTH for a full length one.
Steve: #

Just how much room do you have?

If you have a tuner and room for a horizontal loop, you can make an outstanding #multi band antenna that will be the only wire antenna you need.

For more information and construction details check my website. # #http://k5rcd.airweb.net/ # # # http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

NE6AO
09-09-2006, 05:29 PM
Quote[/b] (k5rcd @ Sep. 09 2006,10:14)]
Quote[/b] (n2mai @ Sep. 08 2006,22:09)]I have plenty of space here at the QTH for a full length one.
Steve: #

Just how much room do you have?

If you have a tuner and room for a horizontal loop, you can make an outstanding #multi band antenna that will be the only wire antenna you need.

For more information and construction details check my website. # #http://k5rcd.airweb.net/ # # # http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif
I think I just said that, ha

KJ4TX
09-10-2006, 12:01 AM
Quote[/b] (wa9cwx @ Sep. 08 2006,14:34)]Dipoles do not require a degree in brain surgery.
What!? I know I've been away for awhile, but you no longer need to be a brain surgen anymore? Man, what in the world is Ham Radio coming too. Next I'll hear that you no longer need to be a rocket scientist either. Then anyone will be able to get a license.



http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif

Mike

W8JI
09-10-2006, 12:14 AM
Quote[/b] (ne6ao @ Sep. 09 2006,09:41)]

Quote[/b] ]Ive read a lot of kurt sterba and he gave an excellent talk on the g5rv and a lot of loss is there if you go to other than the standard band its cut for ,notm to say that it wont work

If old crusty Kurt said that, he is full of beans. If he said that, he is a victim of folklore and myth.

All the additional loss caused by mismatch is documented on my webpage.

My Webpage G5RV (http://www.w8ji.com/g5rv_facts.htm)

The values I gave are for 100 feet of mismatched coax!!! If the line is shorter loss will be even less.

Loss does not just magically appear because some of us don't like the name of a certain antenna.


Quote[/b] ] BUT GET THE ANTENNA HAND BOOK ,the final answers were usually found in the book

That's always a good idea.

73 Tom

N1ESE
09-10-2006, 12:26 AM
When it comes to dipoles, opinions are like arseholes... everyone has one but only W8JI is correct.

K4SAV
09-10-2006, 01:38 AM
A couple of notes about G5RVs. On the higher bands, because the antenna is long compared to a dipole cut for a particular band, the patterns are considerably different from that of a dipole. There are directions where the G5RV should beat a dipole, and there are directions where the dipole will be best.

In general, on 20, 15, and 12 meters, where the G5RV has a lobe it will beat a dipole. It takes the signal and squeezes it into these lobes, leaving a lot of directions with very little gain. On the higher bands the G5RV has several skinny lobes and it is difficult to decide where to point theses lobes because their directions change from band to band. The same can be said for any antenna that is very long compared to a half wave.

For example a G5RV on 15 meters has four skinny lobes where it has good gain. In all other directions it will be poor. At 30 degrees away from broadside, the G5RV should beat a dipole. Broadside to the antenna, the dipole should beat the G5RV by 25 dB because the G5RV has a null. The only G5RV I ever owned had a null on Europe on 15 meters. Guess what I thought about that antenna on 15 meters.

Overall, I consider the G5RV to be a good multiband antenna compared to other antennas in the same class. In order of best performance I think it is 20, 40, 80, 12, and 15 meters. If you remove the matching network and just feed it as a 102 ft dipole with ladderline, the performance in the order of best then becomes 20, 40, 80, 17, 30, 12, 15, and 10 meters (in my opinion).

The G5RV has its weaknesses like any other antenna. You just need to recognize what they are.

Tom, your write-up on G5RV loss was good and certainly agrees with my assessment. The on-the-air testing was interesting and believable, but it doesn't consider the direction to the station making the comparison, or at least the direction isn't mentioned.

Jerry, K4SAV

W0UZR
09-10-2006, 01:48 AM
A friend of mine and I both tried an off center dipole.

It is 90 feet on the center wire, and 45 feet on the sheild side. And most people doesn't have a balun on it, and the SWR is good on all the bands. Works on all the bands. Except 160 meters of course. No antenna tuner.

When I switched to mine from the dipole, everyone's signal went up around 2 to 3 "S" units, and people on the net said I came up 2 S units. And it works a heck of a lot better than the G5RV, and don't have to fight with an antenna tuner.

Try this and you won't be dissapointed.

You can buy one commercially at packettradio.com, but why not just make one?

W2ABU
09-10-2006, 02:42 AM
Great responses, gentlemen. I think that I shall make one and put it up. I just have to figure out how to orient it, NSEW....

Ladder line, better than coax for the dipole? 350 or 450 ohm?

AG3Y
09-10-2006, 03:48 AM
Ladder line if you have a tuner and balun arrangement. Otherwise, I would still say that you should construct a dipole for each band of interest, and feed them seperately. Or you can feed two dipoles ( 80 and 40 that is ) off a single coax feedline with very little interaction. Just keep the ends pretty well separated. ( at least a foot or more ) Remember the 80 meter dipole will not give a very satisfactory SWR reading over the entire band. You will have to decide if SSB or CW/digital is your mode of choice, and cut the antenna longer or shorter, depending on that decision.

You might also consider building your own open wire twin-line feeder. Best of all for low losses and good tuning over a very wide range of frequencies, but a bear to put up because it really should be hung free from any metal influences.

Good luck! Have fun, and try several of the suggestions. None is worse than no antenna at all ! http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

73, Jim

G8ADD
09-10-2006, 09:38 AM
Some things about the G5RV that are often forgotten:

*It was designed as a 20 m antenna with some gain and a good azimuth pattern, its all band capabilities were found later.

*Its originator preferred to feed it with ladder line.

*The design using a ladder line transformer into coax was for 75 ohm coax, not 50 ohm coax.

*There is an improved design with better all band capability by ZS6BKW, with a 27.9 metre top, 10.37 metres of 400 ohm ladder line which matches to 50 ohm coax.

For someone restricted in space and needing a low visibility antenna it is a good choice but it is not a panacea!

73

Brian G8ADD

WZ4I
09-10-2006, 10:41 AM
Quote[/b] (n2mai @ Sep. 08 2006,23:09)]Ok boys and girls, I need some feedback. I am looking for some input on what you think is a good dipole for 40 and 80 meters.

Homebrew or commercial, what do you think?

I have plenty of space here at the QTH for a full length one.

Thanks!!

Steve
If you have the space required, 260ft of wire, fed with ladder line. Will work great down to 160M. Or, 130ft of wire fed with ladder line. Great down to 80M.

W0UZR
09-10-2006, 03:54 PM
DON'T put up a G5RV !

I used one for years, and like I said, I put up the off center dipole, and everything came up in signal.
And we have coax on the antenna. If you use ladder line, you will need a tuner.

WA9CWX
09-10-2006, 04:58 PM
I will add my reduntant $0.02 again.

As just stated, the best bets are the off center, COAX fed dipole, which I have no experience with.
That is the easiest to make, put up and use.

OR, the single coax fed dipole, 80/40 easy to make, a little more hassel to put up if you really keep the wires apart, (mine are about 90 dgs, (crossed) and elevated differently.
That is easy to use, but will only cover about 2/3 of the 80 meter band without a tuner.

Next, a bunch of wire, preferably a half wave or more on the lowest frequency, but not critical, fed in the center, with open or ladder type line.
NEEDS a tuner for balanced line, and THAT CAN be a problem, works same as the dipoles, but obviously can go anywhere. The 'secret' is the basicly zero loss of the feedline. The feedline is the problem in the sense that you can't just run it through a pipe, curl it around itself, etc. HOWEVER, it just isn't ALL that critical.

I have used single band and fan dipoles for over 40 years, and open wire dipoles for 8 years. ALL these things work, and work well.

BTW, I have used various matching things I have read about, all kinds of silly gizmoes added at the feedpoint. For a simple dipole, at tree type height, with random placement of the elements, they are as silly as an electric fork, and less usefull.

G7HEU
09-10-2006, 05:40 PM
http://www.m0heu.co.uk/atu.html

K8JD
09-11-2006, 11:28 PM
I got some MFJ 1:1 baluns and they seem to make an excellent means of attaching co-ax to dipole and have a handy point to connect a center support to a tree or mast. I did buy the balun and ran to Home-Depot to buy commercial grade wire... and even though I soldered my own connectors on I suppose I will call it a commercial antenna.

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