3/14/2021 0 Comments Pa0Rdt Mini Whip Antenna
One option was a magnetic loop, but it still needs some space, and some extra equipment to build it (soldering copper pipes together with a blow torch is not entirely compatible with my current accommodation).Not to mention that a magloop needs constant adjustment in orientation and also tuning.When I saw that the most popular SW SDR receiver stations on websrd.org uses mini-whip active antenna, I decided to give it a try.The receiving surface is a piece of sheet aluminium, 0.5 mm thick, held by two screws at the edge of the board.
The connector is a 50 ohm BNC, which carries the signal towards the receiver, and also the power to the antenna unit. I did not give it a proper housing since I intend to use it indoors only. Maybe later I will build it into a PVC pipe or something like that. I do not have an opportunity to put the antenna outside the house, so local QRM is quite a concern. Interestingly, it is not as intuitive as it seems. To put it as high as possible is a good rule of thumb, but there might be also some hot spots within a room at locations near well grounded objects, like radiators, metal structural elements, etc., so it is always a good idea to try all the available locations thoroughly. ![]() I have an FRG-7, which is not so great in terms of large signal handling. It is easy to find a spot where the S-level is high, but it is much harder to find one when you can actually hear weak stations. The mini-whip is quite susceptible to pick up local noise coming through the feed line from the receiver end. The first and most important thing was to connect the outer shield of the coax to a good grounding point close to the mini-whip. The best grounding point I could find was the valve of the radiator under the window of my room. I also added those noise suppressor clip-on cores to the coax, after the grounding point. I made a few turn coil from the coax as well, to further increase the the choke effect. It reduces the noise coming from the direction of the receiver and also breaking the ground loop. I also added two chokes to the connection towards to the 12V power, to both the positive and negative wire, so the shield of the power unit is not grounded through the 12V PSU any more. ![]() The two green chokes are nicely visible towards to the PSU plug. I found a final place for it where it (usually) does not overdrive my receiver, and the noise level is reasonably low. Pa0Rdt Mini Whip Antenna How To Control CookiesTo find out more, including how to control cookies, see here.
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