|PA1B Fast and accurate power attenuator for CW QSO's|
While testing and making measurements with 5 watts, I noticed that the attenuator section of 20 dB gets warm with in 10 or 20 seconds. So I changed the line up of the sections. By placing the attenuator section of 3 dB in front, this sections will dissipate half of the input power. This line up and the choice of the attenuation, makes it possible to get an attenuation of 10 dB, with the sections of 3 dB and 7 dB switched ON. An extra 10 dB gives an attenuation of 20 dB.
10 dB = 3 dB + 7 dB
20 dB = 3 dB + 7 dB + 10 dB