Effective Power - Elmers Forum at eHam.net

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Effective Power	Reply
by K6IOU on November 15, 2006	Mail this to a friend!
Have heard several discussions about this and can't seem to get agreement from everyone. In the old days Hams were allowed 1KW Input power. Current regulations allow 1.5KW PEP. So . . . with regard to how much power were are allowed to send into the ether . . . and considering the following three modes: CW, SSB and AM . . . are we able to run 'more' or 'less' EFFECTIVE power these days? DON K6IOU

RE: Effective Power	Reply
by W8CAR on November 15, 2006	Mail this to a friend!
The answer for CW and SSB is MORE power. The answer for AM is LESS. Under the old regulations if your amplifier ran 1000 watts input on CW at 60 % efficiency you got 600 watts out. With todays regulations you can run whatever input you need to get 1500 watts out. The same argument applies to SSB. In AM mode we run less power because we are limited to a carrier of 375 watts considering that peaks on AM are usually 4 times the carrier power (1500 watts) Under the old regulations you could have the same amplifier as above with a carrier of 600 watts. Dan W8CAR

RE: Effective Power	Reply
by N8UZE on November 15, 2006	Mail this to a friend!
Remember also that PEP is Peak Envelope Power not peak effective power.

RE: Effective Power	Reply
by N6AJR on November 15, 2006	Mail this to a friend!
all the knobs all the way to the right...:)

RE: Effective Power	Reply
by K6AER on November 15, 2006	Mail this to a friend!
What is peak effective power? In 38 years as a RF engineer I have never heard that expression. For instance what determines effective? I think we have a mix of technical terms. We use; Effective Radiated Power (ERP), generally reference to a dipole also known as dBd. We also use; Effective Isotropic Radiated Power (EIRP) also known as dBi. Both of the above are used in reference to absolute antenna gain. Peak Envelope Power: Is referenced to maximum peak power generally from an amplifier stage. Peak Envelope Power is a maximum sinusoidal or complex peak waveform voltage across a fixed reference load, generally 50 ohms. Peak Envelope Power has nothing to do with modulation duty cycle. SSB duty cycle is about 18-25% duty cycle, CW is 50% duty cycle and FM is 100 % duty cycle. All can have the same Peak Envelope Power.

RE: Effective Power	Reply
by KC8VWM on November 16, 2006	Mail this to a friend!
So . . . with regard to how much power were are allowed to send into the ether . . . and considering the following three modes: CW, SSB and AM . . . are we able to run 'more' or 'less' EFFECTIVE power these days? ----------------- I am not sure I know what you mean by "allowed power"? The regulations state that we are supposed to run the "minimum" (not maximum) amount of power necessary to maintain communications. The amount of power you are "allowed" to operate depends on the situation. 73

RE: Effective Power	Reply
by K6AER on November 16, 2006	Mail this to a friend!
Effective Power; this is an interesting area of interpolation. Minimum power needed for communication will vary depending on your situation and comfort level. Being able to copy a call above the noise floor might be 10 dB. Noise (static) free audio above the noise floor might be 200-500 watts range or about 25 dB carrier to noise for the fellow on the other end Having a DX station just being able to copy your call in a massive pileup for a FT8W station on Crozet Island might require a bad boy amp with plenty of head room and I won't quote the amount of power needed but at least 10 dB above his noise floor which could be S9+30. It is all a mater of perspective.

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