audioguru Posted October 9, 2004 Report Share Posted October 9, 2004 Nice new project. http://www.electronics-lab.com/projects/rf/027/index.htmlSorry, but I am not a ham radio operator and are just curious. Others will be curious too.What frequency or band does this amplifier operate at?Are its output power and harmonics legal? Quote Link to comment Share on other sites More sharing options...
ante Posted October 9, 2004 Report Share Posted October 9, 2004 Audioguru,I Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 9, 2004 Author Report Share Posted October 9, 2004 Hi Ante,I just assumed that this RF amp was rated at "Peak or Maximum" power, like car audio amps, to make the power number twice what is actually true. So with a 42W input from its power supply its actual output is 30W which is reasonable (a little more than 71% efficiency).Its Mosfet is not biased much so it is operating in class-C, and since it doesn't have much output filtering its harmonics must be considerable. It will probably cause TV interference for many km.That's why I asked if its harmonics are legal. Maybe they don't have "RF cops" in the author's country. :-[I am going to guess that its frequency is about 144MHz and on the 2m band. ???A guy on the web is building the world's highest-power audio amp with paralleled transmitter tubes. It uses KW just fot their heaters. He is blowing 500A mains breakers for his entire office building! I think that he uses many km of welded railroad tracks for a dummy load. ;D Quote Link to comment Share on other sites More sharing options...
ante Posted October 9, 2004 Report Share Posted October 9, 2004 Audioguru,You are correct about the over rated power but 30W (71%eff) output requires no heat what so ever. The text does not reveal anything about the input power required for full output power. I Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 11, 2004 Author Report Share Posted October 11, 2004 Hi Ante,Where is the project's author? We are just guessing here.I think that you are correct. I thought that the project is for VHF because its tuning coil has only 2 turns (I was thinking about those FM transmitter toy projects).But now I realise that the tuning coil has a core and its tuning cap is whopping big. So its frequency is quite low and its poor output filtering will probably cause interference to just about eveything.When I was only 16 years old (see, I can still remember that long ago), the RF cops "got" me for using a fan that had a badly-sparking motor (lotsa O2). They said that many people had radio and TV interference because of it. This project might be the same. Quote Link to comment Share on other sites More sharing options...
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