My goal is to run a half watt into I what I hope will be some good antennas. We'll know something this spring. george wi9i
On Mar 19, 2014, at 2:10 PM, Rich/wa4bue wrote: > Hi ZAC > > Seems you have the regs down well. > > You modify it is like Home Brew, still must meet to meet FCC specifications. > > The question is why do you need that much pwer for the satellittes? > > You should keep your power down to a minim to communicate so you don't stress > the birds. > > 100 watts with a 10dB gain is a lot of ERP! > > R > W4BUE > > ----- Original Message ----- From: "Zach Leffke" <[email protected]> > To: <[email protected]> > Sent: Wednesday, March 19, 2014 2:18 PM > Subject: [amsat-bb] External Amplifier Legality Questions > > >> Hello everyone, >> I have a question about FCC Rules regarding external amplifiers. I am >> considering re-purposing a wideband commercial amplifier for amateur use as >> a final stage for my ground station. The amplifier is capable of producing >> about 100W of power between 20 MHz and 500 MHz. I want to use this amp in >> conjunction with coax relays to switch between the 2m band and the 70cm band >> depending upon which spacecraft I'm operating. >> >> My questions are as follows: >> Is it legal to use an amplifier designed for commercial applications in the >> Amateur Bands? This amplifier does not meet spurious signal suppression >> requirements, so I plan to use band specific filters after the amp to make >> sure I knock any spurs down below the required limits. Does the amplifier >> have to be type certified for use in the amateur bands? >> >> As far as I can tell reading Part 97.315(subsection 3), The amplifier itself >> does not need to be type certified if: >> "(3)The amplifier is sold to an amateur radio operator or to a dealer, the >> amplifier is purchased in used condition by a dealer, /or the amplifier is >> sold to an amateur radio operator for use at that operator's station/. >> [emphasis added]" >> >> I'm planning to use it in my amateur station so I don't think it has to be >> type certified. Am I missing something? >> >> Also, The amplifier's 2nd Harmonic is about -30dBc down at 145 MHz. >> According to 97.307e: >> "The mean power of any spurious emission from a station transmitter or >> external RF power amplifier transmitting on a frequency between 30--225 MHz >> must be at least 60 dB below the mean power of the fundamental." >> >> I'm planning to use a filter with about 40 dB of suppression at 290 MHz (2nd >> harmonic), so I get about -70 dB of suppression at the second harmonic, >> meeting the emission requirements of 97.307e. >> >> I see no specific spurious signal suppression requirement for the 70cm band. >> The amplifier has similar 2nd Harmonic characteristics and I'm planning to >> use a similar filter for the 70cm band so the spurs should be down by about >> 70 dB of the fundamental mean power as well. The only wording I see that >> might apply is 97.307c: >> "All spurious emissions from a station transmitter must be reduced to the >> greatest extent practicable. If any spurious emission, including chassis or >> power line radiation, causes harmful interference to the reception of >> another radio station, the licensee of the interfering amateur station is >> required to take steps to eliminate the interference, in accordance with >> good engineering practice. " >> >> I'm taking steps to eliminate interference by suppressing the 2nd Harmonic >> down about 70dB from the fundamental "in good engineering practice" so I >> think I meet all the requirements. Again, what am I missing? >> >> I've heard of lots of hams re-purposing amplifiers for amateur use without >> legal concern, and I think this might be the case for my situation. I'd >> like some advice from those that may have gone down this road in the past. >> Any and all feedback from the group on this would be greatly appreciated. If >> I'm way off, please let me know. >> >> Thanks in advance. >> >> Sincerely, >> Zach, KJ4QLP >> >> _______________________________________________ >> Sent via [email protected]. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite program! >> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > _______________________________________________ > Sent via [email protected]. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
