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Next week a new semester is starting. They gave me more hours to teach, which means more income, but less time to spend on fun things. So I really wanted to finish another project and this week was just the time to do it: an audio filter. In my younger years one of the few kits I build was an notch/bandpass filter. Later I bought the Datong FL-2 and FL-3 filters I always thought it was a must to have one. Ever since I became a ham I thought about building one, but surprisingly there are not many design to be found on the interwebs. Elecraft sells a kit called the AF-1 and they were nice enough to put the schematics on their site. So I gathered the parts and put quite some hours of work in building it according to my own lay-out. The result……

It worked….sort of. But not as advertised on YouTube. I should have known better, so I cleaned up my desk and started anew. Neat and tidy this time and in modules. First up, the power section. Now, how about this?

That’s the way I like it. It worked first time, delivering 12 and 6 Volts. But I’m afraid this is going to be another long term project. Stay tuned.

By the way, after only 41 days I already achieved 25% in the FISTS 25th anniversary Prefix award. The goal is to make 25 CW contacts for each prefix number. Funny to see which number is most issued and thus easiest to score. “7 is up front with 11 entries, closely followed by number 3 with a very respectable 10 entries.” I really have to start looking out for more number six stations. If you have a 6 in your prefix then don’t forget to call me, please.