Friday 20 October 2017

Modified End fed matcher

Since my original post regarding my linked end-fed half-wave antenna and matcher I've decided to extend its range to include 80m. The switch I fitted to add the 60m band was replaced with a centre off change-over type. The extra place on the switch puts a 600pF silver mica cap in parallel with the original tank circuit - 600pF is not a common value so I made it up with several devices in parallel. So with the new switch in the central position the matcher covers 40m  to 15m, first position on the switch enable the 60m band and the second the 80m. The test button that was fitted to put a 3.3k termination in place of the antenna was replaced with a toggle change over type as the original was too hard to operate with cold fingers. The 1k resistor in series with the VSWR dip indicator LED has been replaced with a 4.7k to improve the dip indication - see the accompanying circuit diagram.

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