Re: Sweep Response Results After Completing All Calibrations

Nick Kennedy

I'm glad you are making progress.  I still think your "compensated" output should be flatter and near 0 dBm.

In addition to the things you mentioned, I ran into a couple things getting the coefficients from Excel. One was that it defaulted to too few significant digits.  Getting numbers like 0.02 won't cut if if the actual number is 0.015625 or whatever.  But there is a way to tell it to give more digits.  And also increase the font size so you can see the numbers!  It's also easy to make errors transcribing the coefficients to your parameters file. I've done that a time or two as well.

I do think if the battery is steady at 8.5 V you should be OK on the output of the regulator.

Having your power meter circuit in the same box as the Arduino and DDS probably does raise your minimum signal floor.  But if the effects are constant and repeatable across the range, they still shouldn't affect your frequency compensation, as I see it.


Nick, WA5BDU

On Fri, Jan 23, 2015 at 7:10 PM, n1vc@... [PHSNA] <PHSNA@...> wrote:

Hi Nick,

I did the Excel compensation today. Now from 1 MHz to 30Mhz, the plot starts at +1 dbm and ends up at 30 MHz around -3 dbm. However, there are a few things I have to do first - I never shielded the front end of my power meter as recommended. Also, I have it in the same box with just a copper PCB partition in between it and the SNA/DDS. Finally, I am using a battery PS for the power meter and it is down to 8.5 volts. I would assume it is still regulating and should not cause the reading to vary until it goes below the recommended voltage of the regulator. I have to check that out. I will keep you posted.

Vince N1VC

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