>From what I know about the calibration procedures that one manufacturer
uses, he has a lab calibrated HP436A Power meter and some attenuators that
are used for comparison. If I remember right the 436 has an accuracy spec of
1.2%. Put that together with attenuator and cable errors and you would be
very lucky to come out with 3% accuracy. But it is still probably better
than the accuracy of a bird meter.
73
Gary K4FMX
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> On Behalf Of Jim Barber
> Sent: Thursday, December 03, 2009 1:22 AM
> Cc: amps@contesting.com
> Subject: Re: [Amps] Decent HF directional coupler for RF power meas.
>
> Not to start any trouble here, but what about the newer
> software-compensated meters/directional couplers sold in the ham market?
>
> A quote from a well-known model's marketing material:
> "Power accuracy is better than 5% at any frequency from ~1W to maximum,
> 3% typical with NIST traceable factory calibration"
>
> Assuming 3%-5% is fine and dandy for my uses, do these sound like
> achievable numbers? After watching the Bird comments go by (and having a
> small investment in Bird equipment) I'm starting to check labels... ;-)
>
> Thanks and 73,
> Jim, N7CXI
>
>
> John Lyles wrote:
> > The best directional couplers that I have used for HF power are the
> > Werlatone model C1460, rated for 2 kW through power, with -50 dB
> > coupling (+/-0.5), from 0.01 - 250 MHz. Over the HF portion they have
> > less than 0.1 dB insertion loss and about 24 dB of directivity. They
> > have much ferrite inside the box, and are large things. I own one and
> > have another at my workplace.
> >
> > 73
> > John
> > K5PRO
> >
> >> Message: 3
> >> Date: Wed, 2 Dec 2009 20:14:04 -0500
> >> From: "Carl" <km1h@jeremy.mv.com>
> >> Subject: Re: [Amps] Dummy Loads & Wattmeters
> >> To: "Dr. David Kirkby" <david.kirkby@onetel.net>, "Lynn Osterbur"
> >> <no9z@yahoo.com>
> >> Cc: amps@contesting.com
> >>
> >> Constructing a 1.8 to 30 mHz high power directional coupler with 30dB
> or
> >> more directivity is not an easy task.
> >> Ive built them for 1 or 2 bands at VHF and above and use a HP-437B
> for
> >> accurate results. The couplers are used also to drive the spectrum
> analyzer.
> >>
> >> Carl
> >> KM1H
> >
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
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