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VE2HAR > MT63 12.03.05 21:28l 147 Lines 3268 Bytes #-7312 (0) @ WW
BID : 41900SENTTO
Read: GUEST
Subj: Re: [MT63] Crest Factors
Path: DB0FHN<DB0RGB<DB0AAB<DB0PV<DB0MRW<OK0PPL<DB0RES<ON0AR<VA2HAR<VE2HAR
Sent: 050312/2011z @:VE2HAR.#MTL.QC.CAN.NOAM Laval #:41832 $:41900sentto
One mistake, my average power is around 7 Watts when running MT63 not 12 W.
73,
Mark N5RFX
At 01:04 PM 3/12/2005, Mark Miller wrote:
>Karl,
>
>My setup is a Bird 4431 (model 43 with a sampling port) and a Tektronics
>2225 scope. I first calibrate my scope. I use a single tone to set the
>output of my IC-746pro to 40 watts as shown on the Bird, then adjust the
>trace on the scope for some convenient deflection. I ended up with 4
>gradicules peak to peak. Then I fire up MT63. Since crest factor is Peak
>voltage/RMS voltage, I read the peak voltage from the scope. I then look
>at the average power on the Bird and calculate the RMS voltage by taking
>the square root of P*R where P is the power measured on the Bird and R is
>50 Ohms. I then divide the peak voltage by the RMS voltage to get the
>linear crest factor, I then take 20*log10 of the linear crest factor to
>get dB.
>
>My transceiver is linear up to 45 watts, so I typically use 40 W PEP when
>transmitting waveforms that must be linear. That means when transmitting
>MT63, my average power is somewhere around 12 watts.
>
>73,
>
>Mark N5RFX
>
>At 07:23 AM 3/12/2005, karl larsen wrote:
>
> > Hi Mark, No one I think knows what the crest factor is for MT63, but
> >I am not surprised by your 10DB figure. I run it at about 20 watts out
> >to a 100 watt transmitter so the peaks are not getting out.
> >
> > Please tell us how you made your measurements. Yours might become
> >the "standard"...:-)
> >
> >
> >Mark Miller wrote:
> >
> > >I have just recently measured crest factors (peak to RMS) for a few modes.
> > >
> > >MT63 10 dB
> > >RDFT 8dB
> > >WinDRM 12 dB
> > >
> > >Has anyone else measured crest factors for these modes? I am just
> > >wondering how close I am to the theoretical numbers.
> > >
> > >73,
> > >
> > >Mark N5RFX
> > >
> > >
> > >
> > >
> > >
> > ><< Try MT63 on 80m - great fun!>>
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> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> ><< Try MT63 on 80m - great fun!>>
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