It was very easy to move the components in the layout, and change from an Arduino Nano to a Pro-mini. Switching to the Pro Mini allowed me to stack the display directly over the Arduino. This reduced the width of the board, and gave me a nice probe like form factor. I etched up a board and assembled the new format meter. I had one small error in the board, but a simple jumper took care of that. After changing some pin assignments in the sketch, I had everything up and running. Now it was time to see about packaging it.
I have been playing with the CAD software I use with the 3D printer. I tried several ways to make a housing with a top and bottom piece, but couldn't get one to print that held together tightly.
|Probe Cross Section|
I kept the SMA connector for the input to the meter. That allows me to use a cable to check output levels of modules with connectors, or install a probe tip for in-circuit measurements. One thing I decided to add to the software was to display the difference between the last peak and current reading. This allows you to get the stage output level, then go back and take the stage input reading. The displayed difference should be the stage gain/loss in dB. I took some readings across several known value in line attenuators, and found it very easy to measure stage gain/loss.