Re: Rev 1.40 vs 1.42 results
Hi Ted,toggle quoted messageShow quoted text
The crystal measurement coefficients were added in version 1.42 (or maybe in 1.41, I can not check it now) after realizing that the "normal" set of calibration coefficients accounted for the frequency response of the Generator - Detector combination used for sweeping filters and so, but when measuring crystals there is another thing in the play that have its own frequency response: the Crystal Measurement Fixture. This new set of parameters account for the frequency response of the Generator - Detector - Fixture combination and it is used only when measuring crystals. Before this, the attenuation of the set, that had its own value stored in the configuration file, was valid for a small frequency range, requiring to be recalibrated each time the fixture was used for a new frequency, so there was a box in the program for entering the shorted fixture dBm.
Probably the differences that you see between the measurements done with version 1.40 and 1.42 are due to the fixture attenuation was not measured at the frequency of the crystal and this affects to the calculated series resistance and Q.
73 de Ignacio EB4APL
El 19/05/2020 a las 18:21, Ted KX4OM escribió:
There is an error in that table. I copied the data from a test file and accidentally posted without checking it. The peak frequency of the 1.40 results is 8386.364. I also meant to add that the frequency-related data, peak frequency and bandwidth were almost identical between the 2 data sets, while the RS, Lm and Q are significantly different. Is that indicative of more loss being accounted for? Also, as to the crystal measurement coefficients, are both the sets of coefficients in parameters.txt factored into the calculations in the crystal measurement mode?
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