HF antenna indoors

[mass-man]

FB on the DX!!! what popnokick said...it's an evil combination of receiver, power out, feedline loss, antenna gain, propagation and luck! Sometimes the stars align and you can work DX on a wet noodle. Somedays it takes way more than you got!!!!
Enuf philosophy!!! I would put up a doublet outside on the roof where the green line is drawn...supports could be masts on the ground, as high as practical...it could be 4-6ft supports attached to the eaves and supporting a wire. Feed it with 450 ohm line as close to the shack as you can and finish it off with a balun to a tuner...or a tuner with a built in balun! Its never gonna be a great DX antenna but just being outside and as far away from the RF eating stuff in the attic will be a big help!!!!

 

[SpaceForceCmdr]

Thanks. I was just paranoid I was doing something wrong and it wasn't going to work. It still blows my mind that I can send out a relatively low power signal and it gets out to the world. It's wild

 

[SpaceForceCmdr]

FB on the DX!!! what popnokick said...it's an evil combination of receiver, power out, feedline loss, antenna gain, propagation and luck! Sometimes the stars align and you can work DX on a wet noodle. Somedays it takes way more than you got!!!!
Enuf philosophy!!! I would put up a doublet outside on the roof where the green line is drawn...supports could be masts on the ground, as high as practical...it could be 4-6ft supports attached to the eaves and supporting a wire. Feed it with 450 ohm line as close to the shack as you can and finish it off with a balun to a tuner...or a tuner with a built in balun! Its never gonna be a great DX antenna but just being outside and as far away from the RF eating stuff in the attic will be a big help!!!!

What I really need to do is buy a house. I've been looking for many years, but never found "the one", and now I'm kicking myself because prices are nuts. It's been hard because I have a big piano, and am looking for a specific floor plan. Now, I need to consider antennas, too, haha. I should just move in with my GF, who has a massive flagpole out front already, and just add an antenna to it.

 

[SpaceForceCmdr]

Here's one more:

Kelemen 11500-43251 Kelemen Trap Dipole Antennas | DX Engineering

Free Shipping - Kelemen Trap Dipole Antennas with qualifying orders of $99. Shop Wire Antennas at DX Engineering.

www.dxengineering.com

This thing looks really interesting, and sounds too good to be true. All that band coverage and only 34 feet long? Yes, please! However, I they mention in the documentation that it should be kept well away from structures, so I suppose having it indoors might muck things up.

 

[AK9R]

Research traps and their use in antennas. Yes, you do seem to get something for nothing. But, there are always trade-offs.

 

[SpaceForceCmdr]

Wanted to report back on this topic. I got my Kelemen trap dipole, and hung it up in the attic this evening. Good news is, it tunes up on 30, 20, 15 and 10m. Unfortunately, the FTDX10 won't tune it on 40m. Kind of a bummer because besides 20m, that's the band I wanted most. I guess there are some adjustments that can be made to the antenna to tweak resonance, but it's going to be a pain if I have to keep climbing up there. At this point, I'm just flying blind since I don't have an analyzer.

I guess my other option is to get an external tuner that can do more than a 3:1 mismatch.

As an aside, I noticed that my PC speakers make a little more noise when I tx on 30m than 20m. Is this an indication that the SWR is higher on 30m? Guessing a higher SWR will lead to more RF in the shack?

 

[K8RFT]

For limited areas and specific bands, have you tried hamsticks? Yes, the bandwidth is rather narrow, but if you like a certain band or want a secondary antenna for specialised work, it is a viable answer.

A HamStick dipole up there could be a good way to test operation with an attic antenna. You could hang it from rafters with a couple of pieces of string, or rig a way to mount it on a short mast and make it rotatable. If it seems to work but could be better, then change to a wire antenna and use hamsticks for portable or mobile operating (maybe later on?)

The easiest, cheapest thing I'd suggest is to just string up some wire around the attic, wherever it's the easiest to put it, and then try it out - test it and see what you get. Maybe you have room to put a full-wave loop for 10 meters up there - 10 meters has a lot of DX activity now, and is supposed to keep getting better for a while. (For a loop, you'd also need a balun transformer.) A plain old untuned random wire can work too - but needs a good counterpoise of some kind.

Try out different stuff, and be sure to report your results and opinions! You'll have fun, learn, and help the rest of us as well.

 

[TheSpaceMann]

I have used the 23 foot Ultimax-100 end fed inside hotel rooms, with fairly hood results!

 

[hamstang]

I have used the 23 foot Ultimax-100 end fed inside hotel rooms, with fairly hood results!

I also use the 24' Ultimax 100 as an indoor antenna. Especially good on 20 meters transmit and receive where I've made numerous contacts running just 20 watts.

 

[TheSpaceMann]

It also works well indoors late evenings on 80 meters NVIS! I just run a 23 foot parallel wire on the floor beneath it.

 

[G7RUX]

Thanks, I was looking at some of those, but from what I've read, the feed line ends up acting like part of the antenna and could introduce RF back into the shack.

This does happen but usually because it is being operated with no counterpoise, with the coax braid becoming the necessary counterpoise. This can be avoided by (a) using a counterpoise or (b) putting a feedline choke a handful of metres (yards) back from the antenna feedpoint.

 

[G7RUX]

All that said, choosing one band and getting that working well is a really good approach with HF setups; multiband antennas tend to be somewhat of a compromise and often disappointing, plus a single-band antenna is much easier to get decent performance from.
You can always add bands later.