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#1
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BFO for 465kHz +/- 10kHz
"Pete KE9OA" wrote in message ... http://home.att.net/~n.gianakopoulos...ome.html-.html The above URL should help quite a bit.............I have a universal product detector up there, that will work anywhere from 410 to 600kHz, if you use a black core Toko I.F. transformer that has an inductance in the 600uH range. Just make sure that you have the transformer oriented so the the primary tap is about 25 to 35% above ground. Some transformers are wired so that the tap is reversed. Pete Radio Shack might have a suitable coil in thier inductor assortment. I found a few in those packs, and I used one to make a transistor Hartley oscillator for doing alignments. I don't know if all the inductor assortments have the 455 kHz transformer, or if Radio Shack still sells the assortment. The transformer has 5 pins, the side with 3 pins has the pins you'd use. I don't know what transistor I used or what current I biased it. I don't think any of that is critical. It worked fine on my first try. I got the circuit out of an ARRL handbook. There's plenty on Hartley oscillators on the web. Frank Dresser |
#2
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Series-tuned Colpitts (Clapp) oscillator.
Coil: 250 turns 3/4" long on a 1/2" diameter form, scramble wound. Should give roughly 600uH of inductance. Cap: 100pF varable parallel with enough capacitance (determined experimentally) to give you an Fc of 465 KHz with the variable cap at 50%. -- Gregg *It's probably useful, even if it can't be SPICE'd* |
#3
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You might realign the radio's IF to whatever it takes (465 - 2.7= 462.3 kHz?)
to get 40M LSB. (I think I put the oscillator on the correct side for LSB.) Bill |
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