[AMRadio] Power Levels

Sun Jun 23 12:45:00 EDT 2002

PEP definition:
peak envelope power (of a radio transmitter) [PEP, pX, PX]: The average
power supplied to
the antenna transmission line by a transmitter during one radio
frequency cycle at the crest of the
modulation envelope taken under normal operating conditions. [NTIA] [RR]
(188)

Going by the above, a SSB transmitter with full carrier inserted (or
modulated with a single tone) gives full AVERAGE power. That is the same
power level that would be considered the PEAK ENVELOPE POWER.

73
Gary  K4FMX

Ken Potter wrote:

> Does anyone know the definition of PEP, as it relates to Part 97.
> Ken
> w3kmp
>
> -----Original Message-----
> From: amradio-admin at mailman.qth.net
> [mailto:amradio-admin at mailman.qth.net] On Behalf Of Bob Bruhns
> Sent: Sunday, June 23, 2002 8:54 AM
> To: amradio at mailman.qth.net
> Subject: Re: [AMRadio] Power Levels
>
> Two errors.  The US amateur regulations limit us to 1500W
> PEP output (not input).  If your output is 400W carrier and
> you have 100% modulation, you have 1600W PEP, not 2000W PEP. And the
> 400W carrier output is pretty optimistic if you're
> running 500W input; it assumes 80% efficiency.   Typical
> efficiency of class-C RF amplifiers is 75%, which would give you 375W
> carrier output with 500W input.  At 100% modulation, that comes to 1500W
> PEP.
>
> So the AM community has come up with the approximate rule of 500W
> carrier input, and 375W carrier output, 100% modulated. But the
> regulations actually say 1500W PEP output power, not 500W DC input or
> 375W carrier output.
>
> The FCC has said they would be interested in the size of the transmitter
> tubes and output tuning section. They are not too concerned that that
> someone with a pair of 813's COULD be running illegal AM power, because
> the extent of the violation would only be 2 or 3 dB.  However, they
> would not be inclined to accept excuses from someone with 480V 3-phase
> power feeding a transmitter using a 4CX10000 modulated by a pair of
> 3CX10000s, or from a California-Kilowatt SSB operator with three
> 3CX10000s in parallel.
>
> However, when the FCC has someone on their radar screen and
> the order is to seek and destroy, you can bet that they will raise any
> overpower issue they can.  So the guy who does broadcasts every Sunday
> night and accuses the FCC of being traitors who should be tried and
> hanged, while remarking that he is using a Johnson desk-KW at full power
> plus, will be one of the first ones to receive such a citation.  If the
> other Sunday night broadcaster runs full power on his KW-1 while running
> unattended broadcasts with a Radio Shack timer, he will also be among
> the first cited.
>
>   Bacon, WA3WDR
>
> rbethman at comcast.net wrote:
> >
> > Al,
> >
> >     There is no need to apologize.  Especially for the
> anal retentive
> > individuals.  I do not have Part 97 in front of me.  I do
> believe that the
> > segment covering power levels is quite clear.  It is
> supposed to be 1500W
> > PEP IN to the PA.  There is then the reduction in the
> output in the percent
> > efficiency department.
> >
> >     If your OUTPUT is a 400W unmodulated carrier, then
> modulated at 100%,
> > then the PEP of the output is clearly illegal.  The reason
> is that 100%
> > modulation is four times the carrier.  Hence a 2000W
> output.  This would be
> > a phenomenal occurrences since there would be more output
> than there would
> > be input.
> >
> >     The is a LOT of don't ask - don't tell going on
> amongst the AM
> > community.
> >
> >     I guarantee you that those running T-368s and BC-610s
> that are properly
> > tuned ARE running illegal.  Then there are those that goes
> steps farther.
> > There are a few that run in the neighborhood of 10KW
> output, and some that
> > are running just a few KW.
> >
> >     Don't let the anal retentive individuals drive you
> off.
> >
> >     1) THEY are not the list moderators or list police.
> >
> >     2) You ARE asking a very valid question, and seeking
> knowledge.
> >
> >     3) We all strive to learn, run good clean stations,
> and be good Amateur
> > Radio operators.
> >
> >     Go with peace and ignore those that refuse to broach
> topics that make
> > them uncomfortable.
> >
> > Bob - N0DGN
> >
> > Bob - N0DGN  Craf-T-Bob  (Because I love Hallicrafters!) Apache(2),
> > Mohawk(2), HT-32A, SX-99, SX-101 mk III, R-390A EAC, R-390A Collins,
> > DX-60 w/HG-10, BC-610I, BC-939A
> >
> > _______________________________________________
> > AMRadio mailing list
> > AMRadio at mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/amradio
>
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