I had our friend Grayson (in Turkey) in mind when I put Eddy’s messages about this “thermitron” receiver on the blog.
Hi Bill,
Many thanks for the FB note…
Well, I think my buddy VE3CSK is 99% “hooked” on the notion of making an MFTMM receiver for himself—and that’s a good thing. That rascal of a rig is pretty much fool-proof, & the design sure does lend itself to no end of enhancements / improvements / changes / mods! I should know: with my set-up here I added AVC, and extra IF stage, an extra stage of AF, more pre-selection, etc. etc. etc.
As for selectivity, I simply incorporated regeneration in the 2nd IF stage: with judicious tweaking of the BFO, one can achieve a near single-signal selectivity effect that is GLORIOUS on CW. I guess one can make these things as complicated—or as simple!—as we might chose to do, yet further proof of the flexibility of this receiver.
I’ve taken some jpegs of my set-up here, and am attaching them herewith for your perusal. I like the notion of using these rigs on 80- and 40-meter AM, too—but am presently somewhat “distracted” with the task of re-inking my main tuning dial for my 1929-style superhet.
I think my next step in my MFTMM receiver here will be the addition of an internal 125 VDC power supply—most likely will mount the components inside, on one of the vertical sides (still LOTSA room there!). I have a FB Hammond power transformer that’d be perfect for the job, & I won’t have to connect / dis-connect / re-connect its current out board power supply (that I use with other peripherals, too—a REAL pain by times).
~73~ de Eddy VE3CUI – VE3XZ
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“FB receiver Eddy. Glad more people are doing thermatron projects! From Grayson: Great idea on the regeneration on the IF. an “oldie but goodie” trick. Like to know more. Why second IF? Where did you get the tuning dial? Looks like a real nice one. HB? Keep up the good work!” Grayson TA2ZGE – Ankara, Turkey KJ7UM