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#6
April 15th 09, 08:56 PM
posted to rec.radio.amateur.homebrew
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superregen resonant cavity for narrow band reception - any priorart?
On Apr 15, 8:08�am, "
wrote: On Apr 14, 11:46 am, spamhog wrote: As the sunspot cycle is inching forward, I've been considering adding an upconverter to Charles Kitchin's 50MHz audio-squelched superregen design, in order to make a sensitive and very quickly tuneable 15-30MHz receiver intended to take the pulse of propagation on the higher HF bands. The idea came from an unpretentious Russian design. (No, it wasn't a fremodyne). In a classic case of mission creep, I observed that a fixed IF lends itself to a further step. I searched for prior art in inducing super- regeneration in a resonant cavity. If that could help narrowing the passband, it would be a nice trick for upconversion. I found few and laconic references at almost-otherwordly microwave frequencies, Gunn diodes, folded spectra, etc etc. If I could make a resonant cavity in no time I'd not ask for advice before jumping in, but this would be my very first, and shooting for 40-60Mz IF it risks being somewhat monumental - short of pigtailing the resonator, or doing a folded design, or some other "Grande Complication" which might negate the very idea of using a cavity. ****** Prior art pointers, anyone? ****** TIA Filippo N1JPR IIRC N1TEV's design used a sine wave waveform in the quench oscillator. �As such the receiver is slope controlled, in which case the bandwidth depends upon the rate of change of the admittance across the tuned circuit as it goes into an oscillation condition, and not the Q of the resonant circuit. The standard reference is "Super-Regenerative Receivers", by J.R. Whitehead, Cambridge University Press, 1950. 73 John �KC0G- I meant to say "conductance" not "admittance" |
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