[Amps] Duty cycle for processed SSB in contest conditions?

peter chadwick g8on at fsmail.net
Sun Feb 23 07:59:33 EST 2014


Karl-Arne

>I personally believe that if and when the administrations finally catch up, the results will be lower power limits and type accepted equipment, as in other radio services.<

I am not so sure. Admittedly, requirements for spurious emissions for the amateur services got pushed in as a result of the work of TG1/3 'tidying matters up for all services', formed after the WARC 93 (and the TG1/3 really only came about because emissions from Iridium were interfering with the radio astronomers, who have a surprising amount of influence). The 'Unwanted emissions in the Spurious Domain' as they now are creeps via a very convoluted and non-explicit route into requirements of the Radio Regulations. But the Administrations these days are seeing fewer and fewer engineers being employed, most of whom have no experience of equipment design or maintenance, and administrative bureaucrats who want to spend less money on regulation and international standardisation.

Plus the attitude of less regulation encourages industry.......

But, as you say there is no excuse for a bad transmitted signal as a result of overdrive or misuse of equipment. With homebrew amplifiers, that means keeping harmonics down by at least 43 + 10 log P dB, without needing to be more than 50dB for transmitters below 30MHz and more than 70dB down for transmitters above 30MHz. That includes IM products more than 10kHz away from the transmission centre frequency. 

73

Peter G3RZP




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