HF antenna for townhouse... anything discreet out there?

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drew4392

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If I had a house with my own lot and backyard, I'd have a lot more options... but... I am now living in a townhouse and there are neighbors and an HOA that I need to consider.

Is there a somewhat discreet HF antenna that could mount on a 1.5" mast (off chimney) that you would recommend?

I know there isn't a great substitute for size and more wavelength, but I'm open to whatever might help me get by.


Thanks!!
Andrew
 

drew4392

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Preferably, no attic antennas. Unless an attic antenna would out-perform a small exterior antenna using either the chimney or close-by tree.
 

vagrant

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"Discreet" and "HF antenna" are not friends. A search on this forum will reveal many recommendations and what has worked and just as important not worked for others. A similar question was recently asked. I voted for a screwdriver or loop antenna. If you can get away with something outside of the townhouse, again a screwdriver type or loop antenna are reasonably discreet.
 

prcguy

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If you have your own unit or are on a top floor on the end, etc, a very thin wire can be run under eaves or on the roof in a dipole config or as an end fed with appropriate transformer. If you color match the wire to the building or roof it can be completely invisable 10ft away.

If you can get a wire about 66ft long outside and run as an end fed with an easy to make 64:1 transformer, it works very well on 40, 20 and 10m and much better than anything you could run indoors.
prcguy
 

mass-man

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Ditto on prcguy's suggestion. I have had moderate success loading the raingutters, but you gotta stick to low power levels. I ran coax down the wall, drove a pipe into the ground, laid about 10 radials of whatever length I could, tapped a screw into the gutter, hooked up the coax and ran it to a tuner. I was surprised it worked at all, and actually decently on 20 and 10 mtrs.
 

drew4392

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Thanks everyone. I'm hesitant to run a wire antenna draped over the roof-- or in any horizontal fashion-- simply due to safety. If there are workers of some sort that trip over the wire or break it, I don't want to have to deal with that.

A vertically-mounted antenna is probably best. I never thought of a screwdriver antenna as a base antenna. Or, I read there is a COMET CHA 250 vertical (about 23' high).
 

prcguy

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The Comet is a complete dummy load as are most of the no ground plane verticals. A LARGE mobile screwdriver can work very well but it needs some ground plane under it. If you have a metal railing to mount it on that can be the start of a good counterpoise.

A Yaesu ATAS or similar does not qualify as a large screwdriver, look for something with a 1.5" or bigger diameter coil. You would also want to angle the antenna away from the building to minimize interaction with metal or wiring in the walls.

I get really good performance from a Tarheel 100HP on a large pickup and the same antenna with some metal railing suplemented with several radials or chicken wire can perform about the same or even better if on a high floor and in the clear.
prcguy



Thanks everyone. I'm hesitant to run a wire antenna draped over the roof-- or in any horizontal fashion-- simply due to safety. If there are workers of some sort that trip over the wire or break it, I don't want to have to deal with that.

A vertically-mounted antenna is probably best. I never thought of a screwdriver antenna as a base antenna. Or, I read there is a COMET CHA 250 vertical (about 23' high).
 

joeuser

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I'm going to do the gutter end feed with RG6 2250MHz rated cable that I have one last box of, leftover from when I used to sell, install, & service STARBAND satellite systems.
I'm going to run 25' to one corner & 25' to the drop point in a 'L' shape. I just plan to listen but, you never know. Anyway, a transformer was mentioned for the end feed 1:64... Could anyone elaborate on that please?
 

prcguy

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Ok, I'll elaborate. A half wave center fed dipole is around 75 ohms in free space or closer to 50 ohms when close to the ground as most people use them. A center fed dipole can also be used on odd harmonics like a 40m version will have a reasonable match on 15m, etc. Most center fed dipoles need three attachment points to hold it up unless you want the center drooping from the weight of the coax.

You can feed the same 1/2 wave resonant antenna from the end but its very high impedance and at least several thousand ohms. You can make a simple transformer that provides around 64:1 impedance transformation to end feed a half wave and a 100w transformer costs around $10 including box and connector. An 800w version is around $25. An end fed wire antenna only needs two attachment points and is usually easier to install and hide for condo/townhouse use.

Another nice thing about the end fed half wave is it also works great on even harmonics, so a 66ft long 40m half wave end fed also tunes and works great on 20 and 10m without a tuner. The same transformers will work down to 80m with a 135ft wire but to resonate on 40, 20 and 10m, the 80m resonant spot would have to be in the CW portion around 3.6MHz.

For most people an end fed 66ft wire that has a great match on 40, 20 and 10m is easy to install on most buildings or properties and works the same as a center fed dipole of the same size.

This is not to be confused with a common 9:1 transformer and various non resonant lengths of wire, those dont work anywhere near a resonant end fed as described above. I'm on travel at the moment but can supply a link to instructions on making the 64:1 transformer and a place to buy the toroid cores later.

Your rain gutter setup could work out ok but for transmitting you really want a tuner rught at the junction of the coax and downspout/ground radials.
prcguy





I'm going to do the gutter end feed with RG6 2250MHz rated cable that I have one last box of, leftover from when I used to sell, install, & service STARBAND satellite systems.
I'm going to run 25' to one corner & 25' to the drop point in a 'L' shape. I just plan to listen but, you never know. Anyway, a transformer was mentioned for the end feed 1:64... Could anyone elaborate on that please?
 

joeuser

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Ok, I'll elaborate. A half wave center fed dipole is around 75 ohms in free space or closer to 50 ohms when close to the ground as most people use them. A center fed dipole can also be used on odd harmonics like a 40m version will have a reasonable match on 15m, etc. Most center fed dipoles need three attachment points to hold it up unless you want the center drooping from the weight of the coax.

You can feed the same 1/2 wave resonant antenna from the end but its very high impedance and at least several thousand ohms. You can make a simple transformer that provides around 64:1 impedance transformation to end feed a half wave and a 100w transformer costs around $10 including box and connector. An 800w version is around $25. An end fed wire antenna only needs two attachment points and is usually easier to install and hide for condo/townhouse use.

Another nice thing about the end fed half wave is it also works great on even harmonics, so a 66ft long 40m half wave end fed also tunes and works great on 20 and 10m without a tuner. The same transformers will work down to 80m with a 135ft wire but to resonate on 40, 20 and 10m, the 80m resonant spot would have to be in the CW portion around 3.6MHz.

For most people an end fed 66ft wire that has a great match on 40, 20 and 10m is easy to install on most buildings or properties and works the same as a center fed dipole of the same size.

This is not to be confused with a common 9:1 transformer and various non resonant lengths of wire, those dont work anywhere near a resonant end fed as described above. I'm on travel at the moment but can supply a link to instructions on making the 64:1 transformer and a place to buy the toroid cores later.

Your rain gutter setup could work out ok but for transmitting you really want a tuner rught at the junction of the coax and downspout/ground radials.
prcguy
Outstanding, thank you! Appreciate you sharing that knowledge with us. Its a little ways off but I plan to get this run when it gets cooler. I'll google the transformer.
 

SCPD

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Attic

Preferably, no attic antennas. Unless an attic antenna would out-perform a small exterior antenna using either the chimney or close-by tree.
The question is how big is your attic?

If you can put up a 15 or 20 meter dipole in there, give it a try. Even being inside, I think it will outperform some discreet vertical, or loading up gutters. The flat side is better for DX, in my opinion.

I've worked the world with a G5RV jr in an attic, even with about 4' of the ends bend down to fit.
If you got the room, string up a 15 meter dipole in the attic and see how it plays. Won't cost you nothing to put together.

Or you could string a end fed long wire to the close-by tree.
Paint the wire white, believe it or not, that's the color that stands out the least.
If your gutters are metal, use them as the ground.
A longwire will be directional off the ends after you get beyond 3/4 wavelength, but like the 15 meter dipole, it's not gonna cost ya much to throw up and play with.

But I say phoey on a compromise discreet vertical. Ya get noise, you'll never have a good ground to work against, just not worth all the work involved.
 

joeuser

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From what I gathered from the previous posts the vertical won't be that great. If I had an attic I might give that a try but I'm going the gutter route for sure now!
 

k1agh

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The reviews in the past werent good but there are othersbout there and the current reviews ive seen are positive. Anyone here use a vertical? What about the loop antenna on the same site?
 

khooke

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Anyone heard of this one? It may work for the op.AOR LA800 Wideband Loop Antenna LA-800
Is that receive only? The description says "The AOR LA800 is a wide range receiving antenna..." . There are other magnetic loop antennas for transmit as well (MFJ make one), or alternatively there are plenty of plans online to make one of these. I've seen plans using cable for the loop, or copper pipe, plenty of options. I've been toying with the idea of making one of these myself. The most complicated part seems to be picking a variable capacitor thats will handle the power and frequency range that you plan to use, but there's plenty of advice/guidance online if you search 'hf magnetic loop antenna' you'll find plenty.
 
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