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PHSNA Power Meter Calibration

Vladimir Grijo
 

Hello fellows, I wondering if is it possible calibrate the PHSNA Power Meter using homebrew way. I have a basic oscilloscope (40 MHz bandwidth). Some tips?
Sorry about this basic question, I am starting.
Regards,
Vladimir

Nick Kennedy
 

Hello Vladimir,

Are you wanting to calibrate the power meter for use with the provided software? Or for use as a stand-alone unit?

Most people are using it with the Windows software, I think. 

To calibrate, you need a signal source of known level and a means of providing at least two different levels. This would usually be done at multiple points with a step attenuator. But even a single attenuator could be used. It's more important to get the slope right than to have the absolute power level of your source known accurately.

You have a 40 MHz scope and you need some sort of signal source, which might be the DDS in your PHSNA hardware.  I'd recommend a frequency much lower than the BW of your scope - maybe 4 MHz or so. 

Use the scope to find your power level into 50 ohms.  If that's less than +10 dBm or so, it can be one point and the power through an attenuator would provide an additional point or points. If you do use only two points, they should be widely spaced, like 30 dB or 40 dB.

The PHSNA Windows software provides for automatic calculation of slope and intercept values. The process is described in the User's Guide which you can find in the Yahoo page under Files>Windows PHSNA.  

If you are interested in homebrewing a test source, there are a couple shown on the Yahoo page. One is based on a computer clock chip that produces a square wave, and another is a sine wave source. Both operate at 10 MHz, I think.

Good luck & 73,

Nick, WA5BDU


On Sun, Aug 13, 2017 at 9:07 AM, Vladimir Grijo vladgrijo@... [PHSNA] <PHSNA@...> wrote:
 

Hello fellows, I wondering if is it possible calibrate the PHSNA Power
Meter using homebrew way. I have a basic oscilloscope (40 MHz
bandwidth). Some tips?
Sorry about this basic question, I am starting.
Regards,
Vladimir