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78569Re: Getting more than 1W out

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  • warrenallgyer
    Jul 20, 2014
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      "My unmodified rig also does 160m and 60m with almost no harmonics as far as I can tell with an external rx. "

      I recommend you check this statement again. The standard 80/40 build of RXTX suppresses the 80 meter second harmonic less than 20 dB. That is why there has been a recommendation to use an external low pass filter and the components to build one are supplied with the kit. The filter is absolutely required in order to meet the 40 dB harmonic suppression requirement.

      Operating the 80/40 RXTX on 160 meters will have even less second harmonic suppression and will also have a additional problem. The inter-stage transformer and coile values are such that distortion levels are likely to be well outside the required specifications if used on 160.

      Measurement of harmonics and distortion to the levels that are legally required is going to take more than just "ear-balling" it. Unless you have the necessary instruments to actually measure distortion and harmonics, you should probably hold to the recommended bands and practices in the instructions.

      Warren Allgyer
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