Help a newcomer with SDR Antenna

[NoSlacking]

Hello all,

I'm fairly new to the radio hobby, mostly with an interest in shortwave listening. I currently use a small portable recevier, a Tecsun 310ET. I would like to upgrade to an SDR, but as a newcomer there are some things I am uncertain about.

I've had a bit of a research regarding SDRs and I like the look of the Airpsy HF+ Discovery, but I'm unsure of what to do in terms of an antenna. At home i live on a 3rd floor flat, so erecting a large antenna outdoors is not really an option for me at the moment. Currently I hang a wire antenna out of the window and plug it into the 3.5mm antenna jack on the Tecsun, but for an SDR I would need an antenna with a "proper" connection; which is another thing I am unfamiliar with.

Basically what I am asking is: Can anyone suggest an indoor antenna suitable for HF listening, that is compatible with the Airpsy HF+ Discovery?

[ChrisSmolinski]

You could certainly use the outside wire antenna you use now. You would just need to connect it to the Discovery antenna jack, which is an SMA connector. You can get an SMA adapter that goes to say a F connector and plug the antenna wire into that (you don't really have a ground connection with that kind of antenna to worry about). Or even better yet, connect the wire antenna to some RG6 coax, and run that inside your apartment to the SMA/F adapter. That will help reduce pickup of RFI/noise from inside the apartment. For similar reasons, that is why an outside random length of wire may work better for your application than an inside antenna, which is going to pick up a lot of noise.

Not sure how easy it is to get coax with F connectors in Europe, so you may want to go with something else if needed. But that general idea, coax from the SDR to the outside (balcony?) wherever your antenna wire is.

[Stretchyman]

Antennas don't belong indoors, do you have a balcony as you can mount something to that.

Str.

[NoSlacking]

You could certainly use the outside wire antenna you...

Thanks for this Chris, it makes a lot of sense to me. The thing is, my wire antenna only plugs in through a 3.5mm "headphone" jack, so if im right, I would need an a coax to 3.5mm adaptor for that too, and at that point I think Id be better off just getting a more suitable antenna!

And Stretchyman, unfortunately not. I have very large windows that only open slighty, for 'safety' reasons   

[Stretchyman]

That's a shame but you can try some kind of loop? Either that or maybe dangle a wire out of the window. How high up are you?

Str.

[Ray Lalleu]

Suggesting a fishing rod outside of the window as a support for a wire antenna (connected to the core of a coax), and   wire(s) along the wall - from one window to the other windows - as counterpoise (connected to the screen of the coax). I suggest to make all the wires of the same length, adding nylon wire(s) if that is needed to go to the next window(s). Up to you about how to affix the fishing rod, and about the color. A 3m long rod is not thick. You could experiment with about a 1m length of dangling wire at the tip of the fishing rod. The idea is to adjust the lengths so the least of indoor RFI (on the outside of the coax) is coupled to the outdoor wires. Also use an RFI filter on the AC line to the RX and PC.

[autovon]

Able to mount a loop like this out the window?
Agree with the others, anything outside is going to be much better.  Especially regarding the RF noise you are going to pick up from every electronic thing in the building.  I lived not too far from you in East Anglia for a time, and ran an MFJ1622 inside for a few months.  It worked.  RX and TX were obviously much better once I got wire outside in the garden.





Another idea.
http://www.hamuniverse.com/kl7jrbentvertdipole.html

[NoSlacking]

Thanks for your suggestions guys. I think putting something out of the window like that would probably work. Whats the situation with the size of the loop - is that tied to frequencies in a similar way to dipole setups, or is it just a case of as "big as you can fit"?