Maybe "really precise" is a stretch when you're using scalar instrumentation.
Considering the money we put into rigs and antennas, the ~$500 price of the DG8SAQ Vector Network Analyzer is affordable.
I can remember the days when I had to have some precision attenuation measurements made on a piece of equipment and it took an airplane ride to a sister facility where an HP8410 network analyzer resided in a temperature-controlled clean room.
Later I was able to purchase one of the first HP8510s ($250K) for my work lab. It was rack-mounted and weighed a couple of hundred pounds. At that time NBS (NIST) wouldn't even certify 3.5mm (SMA) standards. BTW, a set of test cables was >$3K. Imagine trying to convince Management that these were throw away items after so many connect-disconnect cycles.
Now I have the VNWA 3 analyzer in my home lab. I can hold it in my hand and within its frequency range, it is every bit as good as the HP and the software is a whole lot more powerful.
Radio-wise, we live in magical times. Wes N7WS On 8/21/2015 11:19 PM, Edward R Cole wrote:
But for really precise SWR I use directional couplers and calibrated open, short and 50-ohm terms. They are never subjected to over +10 dBm. Return loss is what is actually measured and one can use a conversion chart to determine SWR. If I had the money then a VNA is the optimum instrument. But the average ham does not need that.
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