Back tracking your own HF-signal - The use of SDR technique

Online SDR from Pardinho, Brazil

 Did you ever wonder how to make sure that your signal can be heard in different countries while trying to have a DX-contact with them ?

First of all someone might tell you about it but just in case you don't receive an answer of your CQ a SDR website could be used for receiving your own signal while transmitting which provides you the information about if your signal could be received and it also indicates how strong your signal might be in the area where the SDR is located. A Web SDR stands for a Software-defined Radio Receiver which can be tuned via Internet which gives you the abillity of using a remote controlled receiver far away from your QTH without any human responding to your call.

For connections with South America I like to use the SDR receiver from Pardinho in Brazil which is located about 200 kilometers west from the City of Sāo Paolo. It might be also interesting listening to the range of other stations being received in Pardinho you probably can't hear on your own radio but on the SDR. Sometimes those stations are still able to receive your signal i.e. from North America to which I made a QSO to Florida while listening to that station and my own signal at the Pardinho SDR.

Pardinho Web SDR, Brazil

Just give it a try and set your working frequency at the SDR. Sometimes it doesn't need much PWR to hear yourself back. Beside lot's of Brazilian stations there is a big receiving range from foreign signals available depending on propagation. If you are an Amateur Radio licence holder you might choose a quite frequency for testing your receiving signal to this device in Brazil while CB radio operators have to expect way more QRM most of the time. 

The Pardinho Web SDR belongs to the Ham radio OP William, PY2GN, and its antennas seem to be quite impressive not only from the pictures view but also from the receiving range of his Web SDR compared to others. At last this is why I personally like to use the Pardinho SDR much more than different SDR providers in that area.

Martin, LU9EFO, wrote a special report on Willams Web SDR in Pardinho, Brazil.

For other Web SDR pages I recommend the map of Kiwi-Web-SDR on which you will find the best SDR station for your needs worldwide.

73's and good DX, yours Alex, 13CT30

Avoid TV interference on short wave bands - The "Ugly Balun"

The hamuniverse website describes how it works: A plastic tube, 2 lids, wrap a few meters (about 18 - 21 feet) of RG213 around the tube, connect it close to your antenna and you're good to go between 160 and 10 metres.

I made one of these by myself on a 110 mm savage pipe out of the hardware store in town where I also got those lids in which I drilled holes to put a SO-239 socket into each. Then I got the RG213 coax wound around the pipe 17 times so the length of it is about 6,40 metres on the outside while at the end of the wounds I brought some more of it through a drilled hole into the pipe and fixed it with cable ties, then soldered the coax to the SO-239 sockets in the lids and closed them carefully. 

Thereafter I fired up my hot glue pistol which finally fixed the RG213 unmovable in position. Then some hot glue around the sockets to make the whole thing waterproof and well done, finished !

Basically a so called "ugly balun" could be built with the coax completely outside and with PL-259 connectors on it but I have chosen to do it the hard way which means soldering the coax to the SO-239 sockets and then closing the lids without losing the soldered coax off the sockets. That could be kinda tricky.

But fortunately everything went well and it works like it use to be.

The first try was with a homemade T2LT antenna which is better known as a flower pot antenna after VK2ZOI. But I have calculated the size for 10.4 MHz as well as I built it without the so called flower pot which is the resonant balun in order to connect it with the ugly one.

Then I went outside onto the balcony and fixed a 12 metre portable mast with the antenna to the railing. The result of checking the SWR were quite impressive.

The vertical antenna works resonant on many bands as tested on 60 mtr, 30, 15, as well as at the repeater range on 10 mtr ham band.

Additionally to those bands a regular antenna tuner like those equipped in some transceivers can be also tune it on 80 as well as 160 metre band which I could not believe at the first place but that's simply the way it works.

The following night I kept listening to radio stations from far away and I found out that the receiving range with this antenna combined with that ugly balun was large enough so I could listen to some stations around 500 kHz which I've never heard by using a simple end feed wire antenna without balun at the same height.

I am really not an expert in knowing stuff like that but generally all I found out this night was that the Flower Pot Antenna combined to the Ugly Balun works as good as it gets.

But don't get me wrong, that's just a first result which turned out to be good enough and useful. I haven't done more tests yet so don't ask me for further specs about the homemade balun or even the antenna but better visit the website of hamuniverse.com and of course the page from VK2ZOI on which every information about it is published.

For my project well done I have to thank Mr. Don Butler (N4UJW) for his awesome website which inspired me of building the air wound ugly balun as well as I want to thank John (VK2ZOI) who's website also inspired me to build so many flower pot antenna's for different bands and ranges.

Finally I will end up at this point with my last statement about the Air Choke Ugly Balun. Its purpose is not only to be a resonant balun which turns high resistance low down to the wanted 50 ohms but it also works as a wave barrier that brings radiation out of the antenna only but not off the coax which means the power stops radiating at the balun which for sure is not always that ugly.

73 and good DX, yours Alex (13CT30)