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A. schematic diagram. Make before, please check carefully the picture. 1, circuit diagram as follows: B. the production process. before making, please prepare a soldering iron, soldering tin wire, scissors, knife, multimeter and other tools. According to the original check original table.
I decided to build a homebrew antenna tuner because I needed a passive pre-selector network to match an experimental end-fed wire antenna to my QS1R SDR receiver. Please Note: In the last version of my modified FRI-Match (diagram above), I replaced the 470 pf variable capacitors with 500 pf.
The QRP Manual Tuner appears to be the combination a few pieces of work, some that are possible to locate on the Internet. SWR Indicator Circuit - Dan Tayloe N7VE LED SWR indicator
The tuner is built on IM41 bistable relays, which means that a significant current is consumed by the tuner only for a short time during tuning; in rest mode, the tuner's relays retain their state for an arbitrarily long time, without consuming power.
Basic multi-z antenna tuner for QRP. Easy to tune low-z and high-z antennas. This is just an experiment while testing it with my 40m EFHW antenna.
Antenna tuners (or transmatches) are great projects for the budding homebrewer. They're fairly easy to build from scratch, usually very forgiving with respect to component values, and very useful to have around the shack.
Tune Helps Antenna Bandwidth Resonant WIRE antennas tend to function over 5% frequency range with 2:1 or better SWR. So 1/3 of the 80 meter band, most or all of the 40 meter band, and cover most bands above that. 2:1 is an ARBITRARY decision point on “bandwidth” but fits well with the fold-back circuitry on many radios.
