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PEAK & PEP

TonyV225 said:
Mole thats why I brought up the Peak and (TRUE PEAK READING)
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I read your post as the difference between passive PEP meters and active PEP meters. The passive meters just have a capacitor to hold the needle over, while the active meters have the circuitry that Beetle was describing.
 
moleculo said:
I read your post as the difference between passive PEP meters and active PEP meters. The passive meters just have a capacitor to hold the needle over, while the active meters have the circuitry that Beetle was describing.
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Very few of the "passive" meters are even close when used in the "True Peak" mode. If they get lucky with the value of the capacitor they might be within +/- 10-15% of the actual PEP value. Don't forget that even the "Supreme Deity of RF Instrumentation", the Bird 43 has a maximum error of +/- 8% of full scale when the "Peak Kit" is installed (43P).
 
Ok I was thinking the standard peak was like 30% of what the actual True Peak reading would be but then again as stated each manufacture is going to read different.
 
unit_399 said:
Viewing a pure symmetrical sine wave (with no dc bias) on an oscilloscope, the total vertical displacement (maximum positive TO maximum negative) is the PEAK to PEAK voltage. In the same symmetrical waveform, the maximum positive OR maximum negative excursion is called the PEAK voltage, and it is one half of the peak to peak reading. The RMS value is equal to the peak value times 0.707. For example, home electricity is 117V rms, 165.5v peak , and 331v peak to peak.

- 399
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That's some fine brainiakin' boys
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Beetle said:
PEAK power can only be determined for waveforms that are relatively constant, such as power lines at 60 Hz. With purely sinusoidal, constant level waveforms, the math is a snap - and you can easily measure it with a calibrated oscilloscope.

PEAK ENVELOPE POWER (PEP) is a little more complex, since it involves the waveform as modulated by a human voice or by a multitone audio signal. RF wattmeters typically measure average (not RMS) power. There are some meters that have a "PEAK" position on their switches, but these are NOT reliable in that switch position.

Meters that will accurately read PEP must have active circuitry to analyze the RF waveform, do the math, and display it on the instrument's face. In order for the instrument to do that, it needs to have either an internal battery, or an external power source, to provide the power for that active circuitry.

Some MFJ meters (and others, I suspect) have wallwarts available that will power the lights for the meter face. Check the specifications carefully and ignore switch position markings. You're the buyer, so beware.
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I think it is possible to measure peak power of any kind of RF energy, constant or not...
 
QRN said:
I think you and I just read the same post. :headbang :whistle:


I guess the easiest and most basic way to define it is that peak power is the peak or greatest power output that is delivered to a load at any time during operation. Peak envelope power is the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope, under normal operating conditions of an amplitude modulated waveform. Peak is relativley easy to measure. Pep is not quite so easy.
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I'm confused...

While I agree that peak power is the peak or greatest power output that is delivered to a load at any time during operation.

Wouldn't this value be just as difficult to determine as PEP?
 

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