My brother and I built a
10-inch Dobsonian telescope. We modified these
making the tube assembly more accessible and the base significantly
lighter. Photo available here.
QFH Antenna and Software Radio
I built a Quadrifilar Helix antenna (photo) based on instructions found online. The antenna picks up APT transmissions from NOAA satellites that broadcast a right-hand circular polarized signal at 137MHz. I used an rtl-sdr dongle (an inexpensive DVB-T tuner repurposed for amateur radio) as a receiver, stored the signal as a .wav file and decoded the image with WxtoImg (photo). Here is an
excerpt of the recorded signal: