Is it permissable to have both elevated and ground radials? Yes. But with only a few radials (less than about 8 radials per antenna) any radials contacting or very near earth will reduce system efficiency. With less than about 8 elevated radials, a ground rod connected at the common junction […]
ok1rr
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Hams living within cities and urban lots are often unable to erect a tower with a regular Yagi or Quad. Experiments with wires may require a lot of space so many Hams “ending” with a multiband vertical antenna. Regardless of wide availability of many types of such antennas the answer […]
The antenna changeover relay on most linear amplifiers is rather slow, and when the transceiver keys it, there is an RF spark because the RF power appears before the relay has fully changed over. Many modern transceivers provide a delay of 10 – 15 ms between key-down – or pressing […]
by George Wallner, AA7JV This antenna was developed to meet the need by the TX3A Chesterfield DXpedition for a small, low-band, ground independent directional RX antenna that only requires two support poles. The antenna can provide reasonable performance for the space limited amateur, as it fist into a 60 x […]
4nec2 is a completely free Nec2, Nec4 and windows based tool for creating, viewing, optimizing and checking 2D and 3D style antenna geometry structures and generate, display and/or compare near/far-field radiation patterns for both the starting and experienced antenna modeler. When running frequency sweeps, linear or logarithmic style SWR, Gain, […]
Reject unwanted MW AM signals from your RX Front End A nearby broadcast AM station in the Medium Wave band can sometimes cause interference to HF receivers over a broad range of frequencies. A band-stop filter can reject the unwanted frequencies and keep them out of your receiver. This design […]
The KD9SV Front End Saver in a new fashion. If you use a separate receive antenna, you need a Front End Saver to eliminate the possibility of blowing out your receiver’s front end while using an auxiliary receive antenna. Unfortunately, all the radios produced by Icom, Kenwood, Yaesu & TenTec […]
A revolutionary addition to the LF band segment. The principal problem of any LF antenna is its dependence on the ground properties. A low angle radiation is the mandatory, therefore an usual horizontally polarized antenna is useless ifnot located a half wavelength above the ground (i.e. 40 or 80 meters […]
The initial version of Mini-K9AY antenna was published in finnish here. The english translation by Mauno Ritola is here: Mini-K9AY K9AY antenna has triangular shape, height being 7.62 metres and width about 9.3 metres. Mini version of the antenna is much smaller. Height is 1.5 metres and width only 1 […]
In addition to the web interface at http://www.hamqth.com/dxcluster.php there is also new DX cluster node OK2CQR-1, accessible from telnet hamqth.com 7300. It can be defined in your logging contesting in the following way: address: hamqth.com port: 7300 login: your_call_sign (ie. G3ABC) Congrats to Petr OK2CQR who created this very complex […]