With invaluable help from Bob/k6rtm I put together this power inserter using a gutted cable TV splitter. The only part I needed to buy was the 47 picofarad capacitor. I didn’t have an inductor, so Bob suggested making an inductance coil. I used 7 turns of 22 gauge telephone wire with the coils roughly 1/8 inch in diameter (actually, slightly smaller). I wrapped the wired around a piece of 12 gauge copper wire. It works great! Easy to make. Save your money.
A tip to improve: instead of winding the coil over 12 AWG wire (2mm dia), wind the coil over 3/16 inch (4.7 mm) or 1/4 inch (6.4 mm) dia drill bit.
Larger dia coil has higher inductance, and passes lesser portion of 1090 mhz signal to dc adaptor. As a result, larger proportion of 1090 mhz signal goes to receiver.
Coil inductance is proportional to square of diameter of coil.
Aha. Thanks for the reminder. I forgot to post an update with a picture of the power inserter after I replaced the coil with the inductor. I’m not sure I saw any difference in performance after replacing the coil, but I’m more confident it’s working now that I have the right components. Thanks again for your help.
