Category Archives: Mrad-40

Mrad-40 schematic; cleanup, TAK-40 & projects list

I decided to hand-draw the schematic for my little direct conversion creation.  I’d like to put the schematic on a CAD program and file it away in a nicer fashion but I may never get to it.  This is a … Continue reading

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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

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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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Manhattanizing the Mrad-40

I’m almost done with my little Mrad-40 rig.  I didn’t get to work on soldering it into the box as much as I wanted to this weekend but tonight I almost finished it.  The troubles I’m having now are mostly … Continue reading

Posted in manhattan style, Mrad-40, QRPMe, TAPR VNA, transformers, VNA | Leave a comment

Test drive; pi network sim + measurement

What a fun night! I decided to hook up the existing NE602/LM386 circuitry as a “test drive” of my VFO (the circuitry that was in the old version of the MRad-40, on 2 pieces of perfboard).  It worked!  Although with … Continue reading

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