RA 40

RA 40

Wednesday, November 11, 2009

7 Mc Spektrum JF1OZL

7MHz band monitor scope
I made a 7MHz band monitor scope. It exchanges all existing signals of that timing of 7MHz-band to viewer image like a hill on the oscilloscope . See fig5! It indicates what it makes. You know it in the catalog of IC780. ** See fig1! it indicates block diagram. See fig2! It indicates circuit. Saw signal-oscillator makes 11Hz saw signal. This signal controls VCO. VCO oscillates a signal changing from 17.6MHz to 17.7MHz ,repeating 11 times in one second. DBM changes 7MHz signal came from antenna to 10.6MHz IF-signal by mixing the 7MHz signal with 17.6MHz changing frequency local oscillated signal. Yes. This is basically same with normal single super heterodyne radio. But, instead of audio AMP, detected signal is inserted to vertical arc of oscilloscope. Saw signal is injected to a horizontal arc of oscillator. See fig4. It indicates that too fast sweeper make filter dull. This circuit is a type of spectrum analyzer. But vertical hight do not indicate logarithmic strength (dbV) but linear(V). I joint a dipole to this machine. This machine displays a view like fig3. I can know the opening frequency of 7MHz band. I can know where is jaming. I can enjoy to see this view.

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