Category Archives: EMRFD

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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Is 1 Hz/hour good stability? :)

I’ve recorded and plotted data on thermal stability for versions 3 and 4 of my Hartley oscillator.  Below is what I got: V3.0 was the well known basic JFET Hartley circuit from EMRFD (as mentioned before) using a 50-6 toroid … Continue reading

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Progress with stability

I spent more time this weekend refining stability for my LC oscillator. Exchanging the wide spaced air variable for a narrow spaced one helped a lot.  I cut my drift rate vs. temperature in half.  I hope to post a … Continue reading

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Oscillator thermal drift (before vs. after mods)

My version 2.o of the MR radio’s future oscillator is shown above.  I gutted all the extraneous LM386 and NE602 circuitry out of the box so that I could just focus on VFO stability. The box is the original enclosure … Continue reading

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VFO stability quest begins

“VFO building is an art form as arcane as Grandma’s secret pie crust recipe or the fine points of building Cub Scout Pinewood Derby racers.” — Frank Harris from “Crystal Sets to Sideband”, 2010. I began my quest in earnest … Continue reading

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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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