The SWR/Power bridge log-amp version is far more accurate than the diode version… and over a much wider power level.? So for example, the Log-amp version once calibrated (just a single point – S11) gives accuracy of 1db over the entire 92 db power range (-75db to +17 db) of which we only use a fraction of that range… and that is over the entire frequency range of the log-amp (DC to 500 MHz).

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If you are fine with up to 20% error in the power reading (function of frequency and how good the diode is… you can use better diodes but experiment yourself to find the ones that work best.? Good RF diodes cost more but give better results and are more linear over the power and frequency range.? The 1N5711, BAT85, 1N34 etc. are reasonably good choices).? You are subject to the A/D range in the teensy and the way the power section transformer has been wound for attenuation of the RF signal.? That’s still ok… lots of radios use this technique and give adequate results.? The equations to implement are simple.? The software guys can add them in easily.

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Dr. William J. Schmidt - K9HZ J62K(J68HZ) 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ

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Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

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Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it:

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Moderator: North American QRO Group at Groups.IO.

Moderator: Amateur Radio Builders Group at Groups.IO.

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email:? bill@...

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