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SADARS

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2 Dec. 2021 - Using a Nano VNA by Don, G4LOO

Posted: 03 Dec 2021 04:17 AM PST
https://sadars.co.uk/wp/archives/2981




Don began by telling the short history of the VNA. He then described the
make up of the unit and the various iterations through its history. Don
warned the early Gecko version had been the subject of many fakes.

Although the VNA can work as a stand alone it is easier to use connected to
a lap top running readily available software. The initial calibration was straight forward since the step by step instructions are provided at each
step of the action.

He began a live demonstration by measuring the VSWR and Impedance of an
eight element yagi for the high end of 70 cms followed by a 2 m yagi. Both aerials were hand held and the VNA displayed the slight changes in the VSWR
as they were moved about. Also strung up in the hall was a 20 m dipole
which was shown to be in tune. Measurements of the passband of a high pass filter Don had built showed it was working as designed. He also measured
TDR to find the length of various pieces of coax cable. Measurements made
can be stored and recalled later. Don explained several of his files.

He pointed out that the single port device can not only measure VSWR but impedance, phase, return loss, TDR,  and produce Smith charts. The dual
port device can also measure filter response and loss as well as check
cavities and traps for response.

Unfortunately the VNA is supplied without a case, but an inexpensive ABS
shell is available from other suppliers.

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