![]() ![]() The longer coil, which is the antenna side, has taps, equal distance from each end. Why? Because it is cheap and will match just about anything you throw at it.ĪND also because there is currently nothing else available on the market in the 100w class except the ridiculously expensive remote tuner from HamWare! I use it often for portable events such as Field Day. ![]() In addition, tuning this type of matchbox is not always easy, and often the user tunes it wrong, resultingĭespite all of that, I actually own and use one of these! ("Who's perfect?") Unfortunately it is also the technology which has the greatest internal power loss. It uses only 3 components - one roller inductor and two double-capacitors. The Balanced T-Network matchbox is the cheapest technology for building a fully symmetrical matchbox. Using the wrong settings can result in upt to 50% loss of power or more in the matchbox!.Multiple settings can be found which have a good SWR but all of these settings except one result in additional (unnecessary) losses.More difficult to tune than other circuits. ![]() Much higher losses than most other circuits.Be sure to check this BEFORE you purchast that new matchbox! Of two roller incuctors, and you end up with an expensive matchbox.Īlthough the Balanced L-Network is an efficient matchbox, it may not cover the impedance range you require. The switching arrangement must be capable of handling high voltage and high current. This can be done with relays or with a big switch. Although the concept is simple, the implementation is complex. In addition, theĬapacitors much be switchable to both sides of the coil. In order to match a broader impedance range, especially on 160m, several additional 500 pF capacitors will have to be switched in parallel with the variable capacitor. 30uH incuctor and 500 pF variable capacitors), the impedance matching range is somewhat limited. Usually quite a bit more expensive than Balanced T-Network matchboxes.As a result, performance (efficiency) drops off with very high or very low impedances.I am not aware of any Balanced L-Network matchbox that does this - and I only know of one Unbalanced L-Network matchbox that does.For matching extremely high or extremely low impedances, additional compensating components would be required.Complex switching is required to switch the variable capacitor from one side of the inductors to the other, and to switch additional capacitors in parallel.Complex mechanical construction to synchronize the two roller inductors.Capable of matching a broad impedance range "if" implemented properly.In fact there are not manyĬommercial symmetrical matchboxes on the market at all, of any type. There are currently no commercial companies selling this type of matchbox. Unfortunately Link Coupled antenna matchboxes are complex and expensive to build. For this reason they are sometimes referred to as "FILTER TUNERS". This adds harmonic surpression on transmit and rejects out of band signals on receive, Impedances, it also adds a significant amount of bandpass selection on transmit as well as on receive. Besides effeciently matching a broad range of ![]() There are additional advantages to this type of circuit. Originally, most symmetrical matchboxes were built using LINK COUPLING. Once the impedance has been matched symmetrically to 50 Ohms, it can easily be converted to unbalanced using a simple 1:1 balun. These matchboxes are built symmetrically throughout the antenna side of the Symmetrical matchboxes offer the optimum means of matching a symmetrical antenna when fed with openwire feedline. ![]()
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