On Sat, Nov 2, 2019 at 10:46 AM, Mel Farrer, K6KBE wrote:
I have a set of SS SMA PCB mount male connectors that I soldered 4 200 ohms
0603 resistors around the clock, 12,3,6,9 and it measures very close to my
HP SMA termination.
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Mel,
I used a commercially made HP 50 ohm termination as my standard until David Taylor pointed out that even though it was manufactured by HP its s-parameter specs were lukewarm at best. My S11 measurements on known devices were slightly off, but that was because my NanoVNA OSL calibration was made with a load that was slightly off. Changing to a Mini-Circuits 50 ohm load with known s-parameter specs up to 18 GHz solved the problem. To my point, what you have observed may not reflect accuracy unless your HP termination is well characterized.
Of course if you are just using the NanoVNA in a hobbyist environment where measurements within 5 - 10% are acceptable, then pretty much any 50 ohm load or termination assembled using good rf techniques should do.
- Herb
