![]() ![]() I compared the Mini-Whip with the QDFA phased array, and the 310 degrees beverage (225 meters). The first test array was comparing signal levels on the groundwave stations audible here. And just so it's said: On Shortwave the Mini-Whip outperformed all my other antennas with a comfortable margin. ![]() On to the tests! Comparing a small, unidirectional active antenna with directive beverages from 225 to 500 meters long is a bit like comparing a family sedan with a racing car - and half expecting the former to win. ![]() Identical masts have been in use for two winters in the QDFA array, and I don't expect it to collapse or break.Īt the bottom of the mast I made extra room for the feedline to avoid stress and potential damage. This could be improved with better components.Of course, the fiber glass mast needs a support, so I basically used what was at hand. The series resistance of the inductors I chose turned out to be worse than I had modeled. However, I noticed slightly more voltage drop across my power supply filter than I had predicted when I tested it with a resistive load. I tested it receiving WWV, while sweeping the power supply voltage from 8 to 15 V, and noticed the signal quality improve with increasing supply voltage – up to a point. Overall, the active antenna works surprisingly well, given its size. The fully assembled antenna and power supply filter / bias tee box are shown above. The top end cap has a bolted metal hook for hanging, and the bottom end cap has a BNC jack for the antenna’s RF output and DC power input. I enclosed the antenna in a PVC pipe with two end caps. I mounted the power supply filter and DC bias tee in a plastic container, exposing the bias tee connections with BNC jacks and the power supply filter input with a power barrel jack. The frequency response is -91 dBV at 120 Hz. The schematic and frequency response are shown above. I used SPICE on PartSim to model the DC power supply filter and pick suitable component values. I opted to power the antenna from a bench power supply, rather than a battery, so I also built a two stage LC power supply filter on a prototype board, shown assembled at the top left. The kit consists of the antenna and a DC bias tee, shown assembled at the bottom and top right, respectively. It’s powered by an external 12-15V supply, consuming about 50 mA. It covers the entire HF band (3 to 30 MHz) and below (supposedly down to 10 kHz). This HF active antenna is a build of the PA0RDT Mini-Whip from a kit I bought on eBay. Last modified 23:49:48 CDT PA0RDT Mini-Whip Build ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
March 2023
Categories |