Help and information needed please

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steve
Posts: 7
Joined: Wed Apr 27, 2016 6:26 pm

Help and information needed please

Post by steve » Wed May 25, 2016 6:34 pm

I brought the pictured RTL SDR from Ebay a few weeks ago. It appears to be working on VHF (well i can pick up Cardiff and Bristol air traffic). On HF however i only get three stations on AM, Talk sport, absolute radio and some other music channel. I have a Di pole antenna in the garden with each wire being 14 meters long terminating as shown in the picture. I can get no information from the seller and cant even find out what if any off set i should use... I am trying to listen to 5mHz, in particular Shanwick radio and Shanwick Volmet.

I have tried using HDSDR, Sharp SDR and SDR Console V2

If anyone out there can help me to get anything at all on HF i will be very very greatful.

Thank you in advanve
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steve
Posts: 7
Joined: Wed Apr 27, 2016 6:26 pm

Re: Help and information needed please

Post by steve » Wed May 25, 2016 7:47 pm

Sorry, posted the wrong image, here is the one of my antenna terminations...
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rtlsdrblog
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Re: Help and information needed please

Post by rtlsdrblog » Thu May 26, 2016 8:20 am

I've tested one of those units with the large yellow pcb and to be honest it wasn't very good at HF reception. To use it simply choose the Q branch in the settings menu. The better unit is the one with an actual transformer on it, or the one with the built in upconverter.

To get the most out of this one enable the RTL AGC setting to boost the gain. There is no offset required for these because it runs in direct sampling mode.

How is your dipole set up? Remember that the wires should be stretched out away from each other. You might also want to experiment with turning the dipole into a simple longwire antenna which is grounded to a cold pipe or similar.

steve
Posts: 7
Joined: Wed Apr 27, 2016 6:26 pm

Re: Help and information needed please

Post by steve » Thu May 26, 2016 8:39 pm

Thank you for the information... Now confused, does this unit not have an HF converter or does it not need one. My dipoloe wires are pretty much parallel, does this make a massive difference. Sorry to appear clueless but this listening is not as easy as i thought... Could you please send links to the units that you would use.

rtlsdrblog
Site Admin
Posts: 2785
Joined: Mon Nov 19, 2012 11:54 pm

Re: Help and information needed please

Post by rtlsdrblog » Fri May 27, 2016 12:49 am

That unit doesn't have an upconverter, but it uses a special mode in the RTL-SDR called "direct sampling". In direct sampling mode you can receive HF signals, though it is usually not as good as an upconverter. So to simplify your unit can receive HF signals as it is now.

Just checking, when you're using HF mode, you're selecting the Q-branch option right?

Before buying new hardware, first try fixing your antenna. By parallel do you mean like in your photo, with the wires next to each other? The dipole wires should be stretched out 180 degrees away from each other. See http://www.arrl.org/images/view/Licensi ... RL0113.jpg. Putting them next to each other probably won't work very well at all. Ideally, there should probably also be a balun in your coax terminating box, but try using the dipole correctly first.

If space is an issue, try a long wire antenna instead. You can just disconnect the wire on the dipole that connects to the coax shield, and connect the shield to a good ground connection, like a cold water pipe (NOT electrical ground from your wall though), earthing rod, or even just throw the dipole wire connected to the shield on the ground. With a long wire antenna you should also ideally use a 1:9 unun, but in many cases it might not be necessary. See http://s387.photobucket.com/user/Lobber ... e.jpg.html

If you want new hardware then generally I would recommend using a dongle type RTL-SDR (our one is sold at www.rtl-sdr.com/store) and an external upconverter like the SpyVerter or ham-it-up. If you have more money upgrade to an SDRplay or Airspy+SpyVerter. You could also use an upconverter on your current unit, with it connected to the UV port.

steve
Posts: 7
Joined: Wed Apr 27, 2016 6:26 pm

Re: Help and information needed please

Post by steve » Tue May 31, 2016 8:46 am

Thank you for this information. Q- Branch is selected OK. The wires go up the wall for 2 meters then off to the bottom of the garden but with only 20 degrees angle. Will try your advice with dipole and see what happens...

Thank you very much..

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