Commercially-Available Antenna Recommendations? HF 600 watts Attic

[N4UP]

I just moved into a gated antenna restricted community ( given my age I needed someplace both secure and low-maintenance ) and now I must find an antenna my son can mount for me in the large floored attic ( 11 foot peak, maybe 30 x 30 feet of floored space ) of my 2 story single-family home. I could probably fit something center-fed around 45-48 feet in length. Anything mounted outside would be readily visible from neighboring homes.

A long time ago ( I have been licensed since 1963 ) I would have simply built something and installed it myself, but after a recent head injury I no longer have the manual dexterity to build something and would need something my non-ham son can install for me. Thus I need something commercially available, easy to install, which can handle 600 watts and cover at least some of the HF bands. I'd love to work 160-6 meters, but I am prepared to sacrifice 160 and 80 to get something that will fit and work. I have checked catalogs and websites and most of what I have found that can handle 600 watts won't fit, and what will fit can't handle 600 watts. I do have a pretty good antenna tuner.

The "best" fit I have found so far is the Ultimax 100 ( end-fed, random wire, 24 feet ) but I would like something more effective than that if possible.

Any suggestions would be appreciated.

r, peter N4UP

[W9GB]

Peter -

The Alpha-Delta DX-EE total length is 40 feet and will work 40, 20, 15, 10 meters.
An antenna tuner would be required for WARC band coverage (30, 17, 12).
http://www.alphadeltacom.com/pg1.html

No coverage for 160 and 80 meters, due to short length.

[N4UP]

Thank you. I looked at the link you provided and it seemed to be exactly what I need ( power, length, coverage, efficiency, ease of installation ). Then I read the installation directions and it says for an attic installation power should be limited to 100 watts. I understand there may be RFI issues in any attic installation, what with AC duct work and wiring, but 100 watts seems awfully restrictive to me. Are they just being overly cautious, or are there some real dangers running more than 100 watts in an attic?

When I talked with the folks at Ultimax they said no problem running 600 watts in an attic. I have no experience at all with indoor antennas, so I don't know what to believe.

[W9GB]

That would be a good question for Alpha Delta ...
at 600 watts -- heating near ISO-RES coil, end insulators, or
clearances from wooden framing members in attic may be a concern.

w9gb

[N4UM]

A trapped dipole for 40/30/20/15 and 10 might fit - especially if you can bend the ends a bit. You can use antenna modeling software by EZNec to get some idea of the level of rf exposure at various power levels. I have no experience with the Alpha Delta DX-EE but imagine it would also work. Whatever you install could be very hard to feed because of the effects of all the metal and wiring in your attic. I tried the trapped dipole approach but after many days still couldn't get a decent match on more than one band at a time.

I have a wire dipole in my attic and have run up to 1000 watts with it with no ill effects. I installed it so that it is well clear of anything conductive. I constructed 12" standoff insulators by cutting up several lexan cutting boards into 1" strips and use them to keep the wire clear of rafters etc. You want to pay particular attention to the ends of the antenna because of the higher voltages there.

I think your best approach might be to install a wire dipole and feed it either with a remote autotuner mounted near the feedpoint or with ladder line. If your attic is as you describe, it should be possible to suspend an inverted vee at the peak of the attic and run the wires under the roof down to the floor level. Each wire would be about 23 feet long. You could judiciously place a homebrew loading coil of about 10uH at the midpoint of each leg of the wire and should be able to get reasonable results on 40 thru 10.

The thing about attic antennas is that they typically require a lot of experimenting and messing around which your medical condition precludes. I live in a geriatric ghetto where antennas are prohibited and have had good luck with a 23 foot "flagpole" in my back yard. Florida has a flagpole law and the HOA cannot prevent me from installing one. I have a 1.5 KW MFJ autotuner inside a Rubbermaid container on my back porch feeding the flagpole thru 13 feet of good quality Davis RF "Buryflex." The thing works well on 40 thru 10 but isn't so hot for local stuff on 40. Consider the "flagpole option" before going up in that attic!

[N4UP]

Thank you W9GB and N4UM. Based on your advice, I think I will do several things.

I'll contact Alpha and see what they say, but will probably have my son mount both the Alpha and the Ultimax in the attic, as far away from any attic objects and beams as practicable. We'll use line isolators ( MFJ-915 ) where the coax enters the shack. Probably install "mounts" in various places in the attic, so we can experiment with different configurations at 100-200 watts ( my transceiver is 200 watts but I only need about 60 watts to drive the amplifier which is good to maybe 600 watts ) ( would love to run just the 100-200 watts, but I suspect that would be a real challenge to be heard given antenna effectiveness ) ( my last setup included a nice tower and multi-band HF beam and I almost never needed the amplifier ).

I will also look into flagpoles. My HOA doesn't have a problem with them but finding a way to get radials in the ground would be a challenge, given the soil, landscaping, trees, etc. The parts of my back yard that are free of trees have septic lines. I have to be careful, as the HOA has very strict architectural "guidelines" and their procedures are strictly enforced. And I really don't want to ask permission.

If the real estate market ever improves I will see what else I might find with more space for antennas. There are some properties here that are on the river and masked from view by trees, so there I might actually be able to put up a multi-band vertical or modest tower that no one would notice. But given the market, most homes for sale in my neighborhood have been sitting there for three years or more without any offers, so I am trying to adapt to my circumstances.

I am hoping my son will develop an interest in ham radio, but he is still in college and about to get married, so while he is helpful he is also very busy and his priorities are understandable. Thus I need to keep things as simple and as manageable as I can. I even had trouble hammering in a ground rod. Kept hitting my hand instead of the rod. My mind is still sharp ( maybe ) but my hands just won't do what they are told.

In any event, that you both very much.

r, peter N4UP

[N4UM]

I just moved into a gated antenna restricted community

Peter:

You might want to visit the link I've listed below and read my petition to the FCC asking them to require developers and HOA's to make "reasonable accomodations" for amateur antennas. So far over 1800 have signed. It's been up and down this morning so don't get discouraged. Check it out...

http://www.change.org/petitions/fede...and-developers

[N4UP]

N4UM --- Did that yesterday, signed the petition and added my comments. Yesterday ( on another forum website) I saw your thread on the subject and read through all the comments.

Opened my eyes in a number of ways. On the one hand I support the petition and believe FCC rules should take precedence over HOA covenants; on the other hand I can appreciate that my neighbors are concerned about property values and "perceive" big outdoor antennas as ugly. My community allows "modest" satellite dishes that are not "obtrusive" but nothing else. I'd love to be able to put up a decent antenna system, but I do NOT want the HOA to decide what is and is not reasonable ( I want to operate HF and saying I can operate UHF as a "reasonable" accommodation of my hobby is simply NOT reasonable ( not for me, anyway ( no disrespect to the nice folks who prefer UHF )). And yet, I wouldn't want my neighbor to put up something really ugly. So who is to say what is reasonable? I would suggest that allowing a limited number of commercially-available systems ( one dipole, one vertical, one modest tower and beam or quad ) ( all limited to the back yard ) might suffice to allow the ham his hobby but preclude "extreme" antenna systems which most people would consider ugly. But unfortunately, we all see things differently and this is a rather "heated" issue for many people.

That said, thank you for doing the petition. I would have posted on the other forum website ( where I found the petition ) but I only joined and subscribed yesterday and "they" won't let me post over there yet.

r, peter N4UP

[N4UM]

Joe:

Thanks very much for signing the petition. We're certainly not shooting for big towers and stacked beams. I think wire antennas at heights up to 35 feet and verticals up to the same height are about as "reasonable" as we have any chance of getting. I know I'd be happy with a Hustler 6-BTV ground mounted in the back yard and an 80 meter inverted vee or dipole with the apex at 30 or 35 feet.

My flagpole is a good DX antenna but it ties up an expensive autotuner that wouldn't be required if I could just mount my 6-BTV on the same mount I'm currently using for the flagpole. A modest 80 meter inverted vee would give me far better NVIS coverage than I can get with my attic dipole. The attic dipole is fine for transmitting an NVIS signal but the electrical noise in the attic really makes it a very poor receiving antenna.

[WA4FNG]

FYI -- I've worked a lot of QRPers running attic dipoles. 200W should work OK if the bands are open, certainly for CW. If you primarily work SSB I guess you may often need a bit more power.