Lightning Direction Finding

I have abandoned the idea of using the phono pre-amplifier I described in a previous post. I realized that the use of shielded feedlines greatly complicate the design of the loop antenna, and that a balanced feed can be conveniently conducted along Cat 5 cable. 

Today I tried to input sound into my laptop and process it with Mathematica. 

It seems to work OK when I use the built-in microphone or a headset, but not so well when I try to input two channels. 

My Dell Inspirion 15 has a only a single 3.5 mm socket for sound input and output, and somehow I must convince it to take two channels of line-in. 

This is the amplifier I plan to use in the project. I got cheap at a hamfest in Aberystwyth, Wales. 

It has a nice metal box, so shielding should not be a problem. Nice sturdy microphone plug inputs, but RCA connectors for the output. I'm not very fond of those, so I might change it.

The whole thing is very much 20th century inside. Only four transistors and a bunch of resistors and capacitors inside. The transistors are 2SC2240s, which seems to be the right choice. 

• Stackexchange answer on shielded loop antennas. 
• Apparently this page by w8ji is good, but I'm not good enough at antenna design to understand much of it. 
• Meaty stuff on direction finding.