A transmitter has an output of 1000 watts PEP. The coaxial cable, connectors and antenna tuner have a composite loss of 1 dB, and the antenna gain is 10 dBd. What is the Effective Radiated Power (ERP) in watts PEP?

To find the Effective Radiated Power (ERP), first determine the net gain of the system by subtracting the feedline loss from the antenna gain. With a 10 dBd antenna gain and a 1 dB composite loss, the net gain is 9 dB. A 9 dB increase means the signal power is multiplied by 8. This can be deduced using the 3 dB rule, where each 3 dB doubles the power. Three doublings (3 dB + 3 dB + 3 dB) equals a multiplier of 2 x 2 x 2 = 8. Multiplying the 1000-watt transmitter output by the 8x multiplier gives an ERP of 8000 watts. Selecting 10 000 watts means you forgot to account for the 1 dB feedline loss, while 9000 watts comes from erroneously treating a 1 dB drop as a flat 10% reduction of the 10 dB multiplier.