Converting an RF frequency down, and then back up again

Discussion in 'Wireless & RF Design' started by jomac, Oct 7, 2013.

  1. jomac

    Thread Starter New Member

    Mar 1, 2009
    I have a spectrum analyzer which has a tracking generator combined, i want to frequency modulate this CW output without going inside. Ive managed to AM modulate, but FM is a little harder.

    A colleague suggested mixing the output lower (or Higher) using an NE602/612 and then converting it back up again to the original frequency. During this process, one or both of the crystal oscillators can then be FM'd giving FM to the original frequency.

    Im not looking for a super accurate piece of equipment, just something for aligning receivers etc.

    The Analizer has a frequency range of 150Khz to 1050Mhz, and I would like to certainly cover up to 500Mhz. The other suggestion was to do this in 'blocks' ie up to say 50Mhz or more, 50 to 200Mhz and so on.

    He chose 10Mhz to 50Mhz as the first block, but i would like to go much lower if possible to cover 455Khz IF's and again if possible a little higher say 80 to 100Mhz.

    Ive used 602/612's many times before, but not in this sort of application, my question is, what would be the ideal down convert and up convert frequencies to use? Ive plenty of crystals which are 'dead on' a frequency, ie 1,2,4,6,8,10,12,16,20Mhz which are 3rd overtone types. If i have to go much higher with the mixer freqency, i dont mind ordering some to be made.

    Any advice and idea's would be welcome.