Beam Compromise

[KI4WEJ]

I need to find a compromise to a large directional beam. I need something that I can mount to a chimney mast and use a light to medium rotor. I have located a few options but feel free to throw something else into the mix.

Hy-Gain Tri-Band - 10/15/20 Meters - 2 Elements (http://www.hy-gain.com/products.php?prodid=TH-2MK3)

T.G.M. Communications MQ-24SR (http://www3.sympatico.ca/tgmc/mq-24sr.html)

Spiderbeam 20-17-15-12-10m HD (http://www.spiderbeam.net/sb/product_info.php?info=p7_Spiderbeam%2020-17-15-12-10m%20HD.html)

MOSLEY MINI-33-A (http://www.mosley-electronics.com/spec%20files/amateur/mini33a.htm)MOSLEY MINI-33-A (http://www.mosley-electronics.com/spec%20files/amateur/mini32a.htm)

Cushcraft MA5B (http://www.cushcraft.com/amateur/support/pdf/MA5B.pdf)

[n0iu]

Any one of those would probably be a good choice, but I would use some other method of getting it into the air other than strapping it to your chimney. For the most part, chimneys are not made to withstand that kind of load. An alternative might be a 4-legged roof tower like the ones Glen Martin Engineering makes. Here is a link to their website and the various models of roof towers: http://www.glenmartin.com/industrial/pg17.htm Sure, it is a lot more expensive initially plus you also have to poke holes in your roof, but it is a lot cheaper than having a mason (small "m") come out and rebuild your chimney.

Scott NØIU

[KI4WEJ]

Scott,

I thought about that but my load here isn't going to be that much. I'm surrounded by large hard wood trees that keep most all of the wind down. Plus I hope to be looking for my future antenna farm within the next year or so!

[K5RCD]

HEXBEAM (http://www.hexbeam.com/) # http://www.qrz.com/iB_html/non-cgi/emoticons/cool.gif

[NN3W]

I thought the Hexbeam too, but Mike Traffie wants over $1,000 for a triband hex beam. #I ask, "Why"?? #A yagi with all aluminum parts (more expensive than fiberglass) costs half that amount.

[N8ODF]

I have the Mosley mini 33 up about 18' or so & have worked Australia a couple of weeks ago & just this weekend I was chasing mobiles in Wales & Spain on 15M with 100W...seems to work well...is very light weight & even though I am using a Yaesu rotor as I am turning 3 antennas a TV rotor would work very well

[K5RCD]

Quote[/b] (NN3W @ Nov. 06 2007,08:53)]I thought the Hexbeam too, but Mike Traffie wants over $1,000 for a triband hex beam. #I ask, "Why"?? #A yagi with all aluminum parts (more expensive than fiberglass) costs half that amount.

I can only say that I have had one (HX5Bi) at 40 feet for over a year, and if something happened to it I would buy another without hesitation.

This antenna is so stout that I am sure I could drop it off the roof with no damage. It is well worth a thousand bucks to me. It will probably long outlive me.

Is it a StepperIR at 75 feet ? # No, but it is probably the next best multi band antenna option available.

Read the reviews on eham.net#http://www.qrz.com/iB_html/non-cgi/emoticons/cool.gif

[KI4WEJ]

I would love to get the Hexbeam but for the price of that I could have a any of the other listed plus a nice rotor and money left over. So right now the Hex is our of questions!

[w5ww]

Hey Jeremy,

I would recommend the spiderbeam over the others for a number of reasons:

- lightweight
- constructed of wire and fiberglass spreaders. So should be easy to fix
- better usable bandwidth than other antennas
- you can homebrew the antenna if need be
- Active user group building the antenna: http://groups.yahoo.com/group/spiderbeam/

If you sign up for the spiderbeam yahoo group, you can download the construction notes.

Good Luck - Brent

[ky5u]

Take a look at the Butternut "Butterfly" Beam (http://www.bencher.com/hf5b.html). Very light and small.

[ab3fl]

I have a MA5B and it works very well. I have it attached to the side of the house with 4 mast brackets on a 10 foot mast with the rotator and short mast on top of that. So far it has held up well. I would not recommend mounting it to a chimney.

[aa5te]

I'd say the SpiderBeam as you can build it yourself for around $200 (if you shop around for deals on the parts, mainly the fiberglass poles), it's lightweight, and it has good gain on 5 bands.

Having said that, it's a monster, almost 33' tip to tip (10M), but the plans are free, and you can use big crappie fishing poles if you can find them cheap (try eBay).

Here's a website with plans for a 5 band homemade hexbeam.5 band homebrew hexbeam (http://www.leoshoemaker.com/hexbeambyk4kio/general.html)

[ky5u]

Spider beam? 20 meters....

1. Full sized 5el Beam= 6db gain
2. SteppIR 3el Beam = 7db gain
3. Spider Beam = 11.7db gain


Yeah right! ROFLMAO! Gee Ryan, you wasted big $$ on buying that SteppIR dude. You could have had one of these voodoo antennas for much less! GAWD.

[N8ODF]

These measurements are in dbI -vs- dbD...there is a difference...

[dj1yfk]

Quote[/b] ]These measurements are in dbI -vs- dbD...there is a difference...
dBd vs. dBi difference of 2.15dB only. The figure mentioned, 11.7dB, probably also take ground reflections into account (in the order of 5dB), so it all makes sense: you end up with about 4.5dBd of free space gain.

Antenna manufacturers giving high gain figures is one thing, people not knowing how to interpret them properly another.

Oh, and yes, the Spiderbeam would be my first choice of the antennas mentioned by the original poster, based on several occasions where I had the pleasure to use one.

[NN3W]

11.7 dB seems absurd. Standard tribanders with 3 or 5 elements at one wavelength up claim 7 dB tops. 11 dB? C'mon.

[dj1yfk]

A few figures to compare, all of them 3el on 20m:

Optibeam 11-3: 5.1dBd (free space), 12.5dBi (at 20m, with ground reflections)
Spiderbeam: 4.5dBd (free space), 11.7dBi (at 15m, with ground reflections)
F12 C31XR: 6dBd free space, 14 dBi (at 74'..)

http://optibeam.info/OB11-3E.htm
http://www.spiderbeam.net/pdf_files/spider_specification_english.pdf
http://force12inc.com/c31xr-info.htm

All manufacturers specify both the free space gain and the total gain.

[N8ODF]

2.15 Db is the difference between DBI & DBD...I was just pointing that out as most of the manufacturers mentioned were quoted in DBI...Mosley being spec in DBD...I believe the accuracy of a DBD measurement -vs- one in DBI

[ky5u]

dbI= db Imaginary. Yes I know the difference between dbI and DbD. I've also watched antenna manufacturers play the dbI game for 50 years. Put your dbI numbers up against their dbD numbers and let the suckers be hoodwinked.

I think many of us know the SpiderBeam does not have the gain of a 5el beam or a 3el steppIR. I want to ensure the noobs understand what they are seeing.

[KC0ZRX]

I have a Mosley Mini-33a mini beam and have worked over 130 countries with it. #Most of these were with the antenna mounted on a 30 ft. telescoping mast. #I am very pleased with the performance of this antenna. #Weighing only 10 pounds with a 6-foot boom and the longest element less than 17-ft, this little beam is an outstanding performer in my book.

[N8ODF]

Charlie...I figured you knew that...I was responding to yfk... your comment "imaginary" is a good substitution...50 years though...you cant be that old...maybe it just feels that way

[NN3W]

Quote[/b] (KC0ZRX @ Nov. 06 2007,11:38)]I have a Mosley Mini-33a mini beam and have worked over 130 countries with it. #Most of these were with the antenna mounted on a 30 ft. telescoping mast. #I am very pleased with the performance of this antenna. #Weighing only 10 pounds with a 6-foot boom and the longest element less than 17-ft, this little beam is an outstanding performer in my book.
ZRX, do you run power through it? 600 watts is not much on CW - key down.

[N8ODF]

I have a mini 33 & the spec's suggest limiting to 300W

[NN3W]

That is LOW.

[N8ODF]

Yeah...but it works...as I previously stated I have had as much success with this antenna as NN3W

[WA3KYY]

I also have the Moseley Mini Beam on a chimney mount along with my 4-el HyGain 6M beam. All turned with a Radio Shack TV rotor. It works much better than the wire antenna on 20-15-10 in most cases. It gives a better S/N ratio and about 1-2 dB better strength on recieve compared to the wire. Although the F/B is not the greatest, I can tell the difference when trying to work a station off the back vs the front. F/S is very noticable and helps cut down QRM vs the wire.

Any of the lightweight tribanders should be a benefit.

73,
Mike WA3KYY

[KC0ZRX]

I run 600 W PEP on SSB but typically don't run my amp on CW, which leaves me at 100 W CW. #I've heard reports of traps being burned up from too much power into a Mini beam, but have no firsthand experience with this problem. #I also note that Mosley has evidently made some modifications to their original minibeam design, hence they now list it as the Mini-33a, as opposed to just the Mini-33. #Bob, KC0ZRX

[k2gsp]

I built a 5 band Hexbeam from this site. #Hexbeam (http://www.leoshoemaker.com/hexbeambyk4kio/general.html)

I use a light duty rotor and it's all mounted on a mast with Dacron guy ropes. Total cost with the rotor was around 300 bucks. It wasn't hard to build and it works great. It uses the same materials as the spider beam.


This is mine before I pushed it up to 36 ft.





http://i199.photobucket.com/albums/aa108/KI4SXC/Hexbeam.jpg