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Can you give us a typical loss for a tuner matching a G5RV?
"Roy Lewallen" wrote in message ... Unfortunately, simply counting the number of coils and capacitors isn't even an approximate way to judge loss. What counts, mainly, is how much current is flowing in those inductors and how large their wire is (and, if the capacitors have other than air dielectric, perhaps how much voltage is across the capacitors)(*). If you do an analysis of a tuner, you'll find that for a given applied power, the inductor current can vary a huge amount depending on the load impedance. Consequently, the loss can vary a greatly. Lowpass filters are invariably specified when in a circuit with a fixed, specified impedance load. It's not hard at all to design a lowpass filter which has low loss under that condition. Likewise, it's not hard to design a matching network (tuner) which has low loss when the load isn't too far away from 50 ohms resistive. The trick is to maintain reasonable loss when the impedance transformation is extreme. Roy Lewallen, W7EL Fred W4JLE wrote: Let's put this an easier way, how many of you have a low pass filter in line. Most manufacturers claim a .25dB or less insertion loss. These filters consist of a boat load of coils and caps. A tuner normally has 2 varible caps and a single silver plated coil. While any device indeed has loss, here we are picking fly crap out of pepper. |
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