Category Archives: direct conversion

Second order Butterworth BPF

I decided that the broadcast breakthrough was just too strong to live with for my little direct conversion rig, Mrad-40.  I’d made a band pass filter (BPF) already, but it’s roll-off wasn’t stiff enough to knock down shortwave broadcasts, especially … Continue reading

Posted in band pass filter, Broadcast breakthrough, direct conversion, Mrad-40 | 1 Comment

Fixing some wiring mistakes

  The little Mrad-40 is really blasting audio now — now that I’ve fixed two major wiring errors! The audio now is too loud for headphones and can power a small speaker.  But I’m using the amplified speaker anyway just … Continue reading

Posted in Broadcast breakthrough, direct conversion, Mrad-40 | Leave a comment

Transformer 101 to the rescue

In my hurry to finish the Mrad-40 I had used a questionable toroidal transformer leading from bandpass filter to input of the NE-602 mixer. I knew at the time it was a bit suspect but I thought I’d give it … Continue reading

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Bandscan demo of my 40m direct conversion receiver

Here it is, folks, my latest accomplishment —  the refurbishment of my 40m direct conversion receiver, the “Mrad-40”.  See a YouTube of it (and me): Mrad-40 A few notes on it: I’m getting BAD shortwave broadcast breakthrough.  I’d put a … Continue reading

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Final VFO design for the MRad-40

First, if you haven’t already, please check yesterday’s posting about your favorite QRP/homebrew radio resources and leave a comment!  I got great comments already from Steve VE7SL but I KNOW many more people have read the blog since then!  Please … Continue reading

Posted in direct conversion, Hartley, Mrad-40, VFO stability | Leave a comment

New project underway: the magic receiver

This was a great weekend for building and tinkering.  I feel like I learned a lot more and just finally had some time to really enjoy the hobby. The playing with the little 1-transistor rig got me to thinking about … Continue reading

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