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k9jri wrote:
I am looking for a contruction artical or some other starting point for a solid state 5 to 5.5 mHz. VFO to use with my PSK-20. Hopefully somebody can point me to a contruction project, a kit or a source of a VFO. The VFO used in the "Progressive Communications Receiver" by W7XZOI & K5IRK, (QST 11/81; various ARRL Handbooks inc. 1990) is a good stable general purpose JFET Hartley circuit VFO. It can be built to cover frequencies from 2.5 to 10 Mhz. range. The article has charts and calculations to derive component values for the tuning capacitor, and inductor, etc. I've built one to cover exact range you desire. As long as one follows good design practices, such as: use NP0 capacitors only; tuned circuit should be lightly coupled to the FET - i.e. use a small value like 2-3 pF cap., air variable or small ceramic; the VFO will be stable. Power output is around +5 to +8 dBm into 50 ohms depending upon type of dual gate MOSFET used for the buffer amp. Jeff |