AA8IA Amateur Radio

Archive for the ‘vertical’ tag

Indecision causes antenna install delay

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I haven’t reached a decision regarding purchasing a Cushcraft R-8 or a HyGain AV-640. To make matters worse, I am rethinking the possibilities of a ground-mounted installation such as a Hustler 6BTV or a 33 foot vertical.

When it comes to verticals, there are too many options. I still have unanswered questions as well. Primarily, i need to know the consensus on R-8 or AV-640 performance at 10 feet off the ground vs a ground-mounted Hustler 6BTV with a slim radial system to start and a radial system that is unlikely to ever contain more than 32 radials or have any radials longer than about 30 feet.

In the meantime the pressure is growing for me to get something up and operational. Field Day is only two months away now. I’ve been thinking about a dipole.

Nowhere on my lot can I proper install a dipole that will work for 160 or 80 efficiently. At this point I’m questioning whether it would even be feasible to try to install a dipole long enough to cover 40m. This would need to be ~ 66 feet long. The only way I could really do this is to have the feedpoint in the center of the house roof and have something to secure the sloped ends near the edges of the house. The house roof is ~70 feet across. I prefer not to put anything on the roof. An alternative would be to have some sort of mast up in the rear of the house to use as the center support, but then I’d have to figure out how to secure the ends. I would not want the ends to be anywhere near the ground (at least 8 feet off) and would end up having to put some sort of support in the ground on either side to accomplish this.

So, I’ve been thinking about a wire for 20 through 10 meters. This would be 33 feet in length. The orientation is not what i would want. I estimate that if I put up a wire for 20m using a tree as one of the supports, the orientation would be E-W, which means it would favor signals to the North and South. That leaves out a good path to Europe. Although, I wouldn’t mind nabbing some South America.

I really don’t believe I’ll have have something up that is efficient on 80m. At some point I may decide on putting a vertical up. If I do, it’ll only be a mediocre performer on 80 and the bandwidth of the antenna on that band will be very minimal.

I’ll ramble some more later.

Written by Mike

April 26th, 2010 at 8:41 pm

The X300NA is On The Air

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I received the Diamond X300NA today.   Took me about an hour to put it together on the kitchen table (trying to be quiet since baby was sleeping).   The instructions were very simple.   The antenna went together very easily and is actually simple to put together.

I can’t really give a performance comparison for multiple reasons.   First off, the antenna is only 4 feet off the top of the deck table.   Second, I didn’t have a previous transmit antenna at this location to compare with.

On receive, it performs as well or better than my scanner antenna on 150-174 mhz and 450-475 Mhz.   800 Mhz performance, as anticipated, is terrible.   I haven’t gotten a chance to compare 2m / 440 Mhz signals since I haven’t listened to any 440 Mhz amateur repeaters in a long time and I only monitor a few 2m frequencies.   I’ll try to test it out a little more this evening.

I really need to get this antenna up over the roof of the house.   As it is now, the majority of the antenna is below the roofline and close to the house.   If I could get a 21-foot fence rail as a mast, mount it on the ground at the side of the house with a proper support at the eave, I’m sure it would do great.   This will be my only alternative at present, and it’ll probably be at least a month before i get that accomplished.

Written by Mike

April 7th, 2010 at 1:29 pm

Posted in Antennas

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HF Vertical Antenna Considerations

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I’ve been looking into various options for multiband HF operation.   The cheapest and easiest [typically] would be a variety of dipole fed with ladderline.   The problem is my lot size.    The whole lot is 100×150, but the house, side yards and front yard occupy 75×150 and the remaining 75×150 is occupied by a back deck, underground utilities, a fenced in area for the dogs, and a small portion of wooded area — no trees at all on this part of the property.

Over the years I’ve used various wires, and they always performed better than nothing but they never performed, mostly due to me never having an option to put them up at a proper height or with a proper length to work all the way down to 80m.   Forget about 160.

So I’ve been looking at various verticals.   Some pros to a vertical is that you often can fit them into a space that a wire cannot fit, and they have a low takeoff angle so they are fairly decent DX antennas.   Some cons are the fact multiband verticals tend to be long and sometimes cannot handle the abuse that a high wind area poses; also many require a radial system, and constructing a proper radial system [especially if you are ground mounting a vertical] is not for the faint of heart.

Option #1:  Ground-Mounted Vertical

A Hustler 6BTV falls into this category and would be my vertical of choice if I was able to ground mount it.   I typically would not have had an objection to a ground-mounted vertical.  However, GMVs require a proper ground system to work as advertised.    Just because a vertical may tune up with or without a tuner without the use of radials doesn’t mean it’s radiating the signal where it is most useful.   I’ve been doing a lot of reading about radial systems, and although I would not object to going through the trouble to install a proper radial system, it’s just not in the cards.      It is recommended that a GMV be located at least 20 feet away from tall frees, houses, metal structures [including fences].   It is also recommended that the ground system consist of at least 20 radials cut to at least 1/8 wavelength on the lowest band that you wish to operate (33 feet for 80m and 16 feet for 40m).

In the area where I could possibly install a GMV there is a fence surrounding it within 15 feet of the location and a septic system and underground electric beneath it.   I could never lay out a proper ground system with the fence in place, may have trouble with interference from the underground electric, and would certainly have a problem with the chain link fence being in close proximity to theantenna as well as the house and tall trees just beyond the property line.

Option #2:  Elevated Vertical without Radials

I’m not sure how well this category of verticals works, but one antenna in this category is the Hy-Gain AV-640.    This antenna is an 8-band vertical (80/40/30/20/17/15/10/6) that does not require a radial system.   It is 25-1/2 feet tall and weighs 10 lb.   I’ve read good reviews and bad reviews.   The bad reviews included reports of missing parts upon shipment, sometimes shoddy craftsmanship (holes not lining up, burs around machined edges), water intrusion into various parts of the antenna system where it does not belong, etc.   Good reviews include the fact that it is easy to put together, easy to work on, works very well on 10m-30m whilst being somewhat of a compromise on 40m, is easy to tune, and that is pretty good at withstanding the wind.

An Antenna like the AV-640 is more of an option for me.   However, I’d still like to get it up in the air.   I don’t have a tower, but i believe I have the needed real estate to erect something and will likely pursue that.   I’d mount an AV-640 elevated, but not with a height clear over the top of the house at this point.

Summary:

Obviously the low takeoff angle bothers me for working local, but unless you have money and available real estate you can’t always have your cake and eat it too.   I like working predominantly the state QSO parties / contests and Field Day.    I do occasionally participate in other contests that are worldwide.

I do like the vertical because it takes up minimal horizontal space, doesn’t require wires strung all over the place, is easy enough to construct and put up, and is easy to maintain.

I’m likely going to go with a vertical that does not require a separate radial system such as the AV-640 (but perhaps not the AV-640 when all is said and done).   When this will happen, I am not sure.

Written by Mike

April 6th, 2010 at 8:52 pm