Re: Progress with my PHSNA calibration

Nick Kennedy

Glad it's coming together. I use the same system - the CMOS square wave generator, which then calibrates the VE7BPO sinewave oscillator.

I was just thinking I should offer to run your Excel data file through my program to calculate the coefficients, but I'm glad you found a better way.

Watch out for it defaulting to a small number of significant digits on the coefficients. There are plenty there, but you may have to tell it to show them.


Nick, WA5BDU

On Wed, Nov 16, 2016 at 5:59 PM, anglerhamming@... [PHSNA] <PHSNA@...> wrote:

Hi everyone,
Latest update.  I zeroed out the polynomial coefficients in the Parameters.txt file. Next,  took new data with the homebrew VE7BPO -10 dBm sine wave calibrator (checked against the K3NHI CMOS -10 dBm square wave calibrator) and my homebrew step attenuator inputting to the LPM with the SNA running. I got data from the SNA at the 10 dbm points from -10 dBm to -70 dBm. The PHSNA program calculated the slope (0.09083)  and intercept (-82.93 dBm), which I manually entered into a copy of the Parameters.txt file. Then I connected the SNA output to the LPM, and I took data of actual dBm from 1 MHz to 30 MHz in 1 MHz increments. I entered the dBm data points into an Excel 2003 spreadsheet, and I got the scatter plot with the 5th order polynomial trend line. I couldn't get the actual equation at that point, so I brought the .xls file upstairs and imported it into my wife's business PC that has a much newer version of Excel.

Tomorrow, I will enter the coefficients of the equation into the Parameters.txt file and then proceed with setting up for the return loss bridge (a homebrew version) and the crystal test fixture. This stuff is really interesting!

Ted, KX4OM

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