> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Gudguyham@aol.com
> Sent: Sunday, July 16, 2006 7:01 PM
> To: df3kv@t-online.de; amps@contesting.com
> Subject: Re: [Amps] FW: Transformers
>
>
> In a message dated 7/16/2006 7:53:46 P.M. Eastern Standard Time,
> df3kv@t-online.de writes:
>
> The crest of the envelope in that example is 400V.
> Since 400V peak equal 282V effective, PEP power is 1600W not 3200W.
>
> 73
> Peter
>
>
>
> The measurement was made with a scope and the highest peak was singled
> out
> and at that point the peak power was 3200 W, but looking at the complete
> wave
> including the low spots the PEP would be 1600 per definition. Now I
> guess we
> have to ask Rich what he is driving at. To qualify my answer I would say
> that the peak power was 3200 W but the PEP power over the completed wave
> was
> 1600. W
Hi Lou
You are missing the definition of PEP. It is the AVERAGE power at the crest
of the modulation envelope over 1 RF cycle. Not the peak power. Peak power
is not used for anything in these type power measurements.
To find PEP you must first find the RMS voltage of that peak that you
measure. Then square it and divide by the load impedance. That gives you the
1600 watts PEP. (There are usually many RF cycles involved in one
modulation peak as the RF frequency is much higher than the modulation
frequencies.)
This business of PEP being twice the average power, as read on the meters,
is true only with a two tone test. With voice the PEP will be anywhere from
3 to 5 times or more of what the meters read. This of course if the amp is
not being overdriven or heavy processing used.
Also note that the PEP will never be higher with voice than it is with a two
tone test, but the average as read on the meters can be much lower with
voice than the two tones.
Where some of the advertisements about power ratings came from way back
when, some of the manufacturers said that if the CW rating of the amp was 1
kw input then the PEP was 2 kw. Several manufacturers were guilty of that.
Note that if an amp is capable of 1 KW input on CW then its PEP input is
also only 1 KW input. (SSB PEP can be somewhat higher because of less
voltage sag in the power supply)
73
Gary K4FMX
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