Sometime in the 1960's or early 70's one company started offering a 9 MHz filter at a decent price that was widely used by homebrewers back then and the subject of many QST and ARRL handbook designs as well as a number of "commercial" rigs.
Obviously, those rigs up-converted the lower MF frequency bands and down-converted the higher MF frequency bands. Early M.F./H.F. superhetrodyne receivers all "down converted" to an I.F. in the low MF range (usually 455 kHz) but designing input filters for the M.F. range that would adequately reject the image response at 2X the I.F. became very difficult. Filter technology limited the selectivity available at higher frequencies, forcing designers to use a low frequency I.F., but the press was on from the beginning for better I.F. filters at higher frequencies. Like all designs, it's always a compromise. The best designers are those who make the best compromises using the components available at an acceptable price. Ron AC7AC -----Original Message----- There is a serious misconception by some true believers that Elecraft "invented" down-conversion (or at least conversion) to an i-f in the 8 to 9 MHz range. Nothing could be further from the truth, and I know that the folks at Elecraft would never claim as much. I had a Henry Radio Tempo-1 (Yaesu FT-200) back when radios warmed up the shack. It was a 9 MHz i-f transceiver. Wes Stewart, N7WS --- On Tue, 11/16/10, Benny Aumala <[email protected]> wrote: > > When K3 came I told this RX architecture will soon be a > standard > (as Rob Sherwood told long time ago). ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
