Good point. I just emailed W5BIG (the VNA designer) with this question. He
said that the VNA2180 has been lab-tested with precision calibrated
attenuators. The VNA2180 was off a maximum of 0.3 dB with a 60 dB
attenuator, and a maximumn of 0.5 dB with a 70 dB attenuator through 140
mhz.
Phil - AD5X
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at
> contesting.com]
> On Behalf Of Phil & Debbie Salas
> Sent: Monday, December 07, 2009 12:32 PM
> To: amps at contesting.com
> Subject: [Amps] FW: Decent HF directional coupler for RF power meas.
>
> "The cable and attenuator errors can be known without error, all he has
> to
> do is pay a
> cal laboratory to characterize each at the test frequencies."
>
> I've watched the Array Solutions guys calibrate their PowerMaster
> couplers.
> They use their VNA2180 to accurately measure their cables and
> attenuators.
> So the only inaccuracy is the tolerance of the HP power meter.
>
> Phil - AD5X
>
There is also the inaccuracy of the vna that has to be added in also. They
don't say what that is.
73
Gary K4FMX
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