dBCalc: Signal Power & dB Comparison

KD WY5R & David KJ4IZW

JT65A on HF, or Terrestrial JT65, is a weak signal mode with it's roots in EME/Moonbounce operations. It is a data mode designed to copy signals as much as 15dB below the noise level. On HF, operators take this ability for granted by using power levels which are not necessary. It is recommended that you examine your logbook on a regular basis, and check your average signal report. If you find that you consistently receive signal reports better than -10 dB, you can safely lower your power to 1/4th or 1/8th of what you currently use. The purpose of dBCalc is to provide an operator with alternative power levels required to acheive other readable signal reports with programs such as WSJT or JT65-HF.

To calculate alternative power levels, enter your current power output in the TX Power box. Next, select the signal level you received from your latest QSO. You will be presented with a list of power levels required for other signal reports to the same station.

TX Power: Watts
Signal Report: dB


Report Power
-01dB 25.00 W
-02dB 19.86 W
-03dB 15.77 W
-04dB 12.53 W
-05dB 9.95 W
-06dB 7.91 W
-07dB 6.28 W
-08dB 4.99 W
-09dB 3.96 W
-10dB 3.15 W
-11dB 2.50 W
-12dB 1.99 W
-13dB 1.58 W
-14dB 1.25 W
-15dB 1.00 W
-16dB 0.79 W
-17dB 0.63 W
-18dB 0.50 W
-19dB 0.40 W
-20dB 0.31 W
-21dB 0.25 W
-22dB 0.20 W
-23dB 0.16 W
-24dB 0.13 W
-25dB 0.10 W
-26dB 0.08 W

Website by David - KJ4IZW - dwestbrook@gmail.com