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I'm making the 146.5MHz bandpass filter in CQ250 described by Shaun. Can anyone confirm the coil diameter? The type doesn't get any clearer when enlarged. I've guessed it's 3/8" diameter and wound 4 off 6.5 turns on a 9.5mm drill
The rush is on to get filters ready for CAT17 workshop day.
I built one in a diecast box and they work extremely well. A friend found the copper clad board design unstable due to flexing.
http://www.m0skm.com/index.php/2m-band- ... er-another
Pictured is progress to date. I'm stuck for what to do with the 0.5pF "capacitor" wire. It's not connected yet. Hopefully at Saturday's workshop session at CAT17 all will be put right.
- 146.5MHz bandpass filter under construction
- 20170903_CQ250_bandpass_filter_part_built.jpg (179.52 KiB) Viewed 2464 times
At one end the inner only connected to the cap/coil junction; the other has the outer connected to cap/coil.
Edited as first post too early in the morning Oops.
If you were to bring the filter to Finningley, we'll have a spectrum analyser and sweep generator suitable for setting it up there. Please bring the lids so that we can close it up when we get it right!
CAT17 workshop day is very important to me as no working spectrum analyser is to hand. I'll have plenty for Dave to examine! E.g. the QRP-LABS low pass filters for 4m and 2m as well as the new M0HMO power meter that I built at GQRP club Buildathon on Saturday.