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The first picture is the night before Airventure and I have taken the radio out to be swapped.  After returning, the new radio swapped right in and worked perfectly.

As always I am delighted to have visitors to the shop. The second picture is of my son Scott, his wife Thazin and Thazin parents. I had the panel fully functional and let them both listen in to the radio chatter from Midway and O’Hare.
      These two pictures show yet another change to the dimmer circuits.  For anyone who has ever done hardware or software integration you will know my pain.

      I needed to get three different devices to work together to dim the lights of the comm. and transponder.  When buying the components I had good documentation about the two devices except exactly how the backlighting worked in each unit. Those two units and the dimmer itself all had different ideas about exactly how they should work.  I also had the initial dimmer device fail in one channel.  I replaced it with two, one channel devices.

      The dimmer devices themselves are the main culprit. It turns out, even though the dimmer has an on off, they never go all the way off. The dimmer has two leads to power itself and then two leads that go to the device. When I was doing my initial checks of the completed wiring, I was testing each circuit for its draw to compare with my planning.  It turns out that the dimmers are always drawing at least 2 ma. Not much, but in a hanger in the winter without much activity, that will drain my battery.

      In addition, because the off switch doesn’t actually shut the leads to the device off, my always powered light circuit wants to power the backlight of the radio and draws more like 30 ma. The long and the short of it is, the transponder is out of the backlight loop and does its own dimming. The radio backlight is jumpered to its own power input undimmed, and the cabin light switch has been changed to a double pole switch so that power to the dimmer unit itself can be shut off. Last but not least, the now unused second dimmer has been yanked so there is an empty hole in the panel and some new labeling will be needed.  Oh well.