![]() A pdf document from a QST article made available for novices and beginners by ARRLĪ small HF antenna tuner project for qrp operations. The published version of this article appeared in the February 1990 issue of QST Magazine It all depends on the type of antenna and feed line you're using. Another possibility is to use a BNC female as this can plug straight on to BNC equipped transceivers.Įither scrounge a lunch box from the kitchen, make one out of circuit board material or consider one of these.Maybe yes, maybe no. Risk of you leaving a coax patch lead behind. This may make the coupler harder to pack but means that there's no Some homebrew QRP rigs even use RCA connectors to save money.Īnother option is you could have a flylead with plug to fit straight into your transceiver. Sockets to connect transceiver and antennaĬommon antenna socket types include SO239 (to accept PL259 plugs) or BNC. Requires the top to be open to permit easy access. Another approach, if you don't have a switch, is to use an alligator clip to tap onto various parts of the coil. Heavy duty switches are required if you wish to run high power. The more positions the more taps you can have on the coil and the wider the range of antennas you can match. Enamelled copper wire, such as found in old power transformers, is good for the coil windings. In the circuit can either be varied with a switch or a wander lead with alligator clip. Unless you can get a roller inductor you need to make your own tapped inductor as described above. Variable inductors aren't as readily available as variable capacitors. The value isn't that critical but aim for one with a maximum of around 200pF. The air dielectric version is heavier but can take a higher transmit power and is easier to add a knob to. ![]() The plastic type is smaller, lighter and cheaper. Here you have a choice between a plastic dielectric variable capacitor and an air dielectric type. You may not be able to find the exact parts used but substitutes should be obtainable. Though this can be hard to see in bright sunlight.Īntenna couplers galore More antenna coupler plans and video demonstrations ![]() It's desirable to have some sort of tuning indicator if your rig does not have inbuilt SWR indication. However it's a good idea to keep leads short as this will allow the unit to function correctly on high HF bands such as 10 metres. However if you want to run more power, then you'll need heavier construction, including the use of an air-spaced tuning capacitor.Ĭonstruction is very simple. ![]() Both these parts will stand 5 watts QRP power. The capacitor can be a plastic variable type salvaged from an AM radio. The coil can be wound on a piece of 25mm plastic pipe, or if space is limited, on a iron powder toroid. Usually the coil is tapped while the tuning capacitor is continously adjustable. Both need to be variable to match a wide range of antennas, although it's OK that only one is continuously variable. So what is an L-match? It's just two components - an inductor and a capacitor. An L-match is particularly suited for backpack style portable operating as they can be made so small and light.Īn L-match plus a thin wire antenna is lighter than a coax fed dipole and allows operation on multiple bands as well. It comprises just two components - an inductor and a capacitor. The L-match is the simplest way to transform the widely varying impedance presented by a wire antenna to the 50 ohms required by the transceiver. Vk3ye dot com - Compact L-match for portable use ![]()
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