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 3-3.5w fm transmitter

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sm976 Posted - Mar 08 2014 : 12:40:51 AM
http://www.aaroncake.net/circuits/3wfmtran.gif

i have seen your transmitter circuit.. and i want to build this..
but my problem is i could not find BB405 varicap , so can i replace this diode with BB109 ???
please help me?? its urgent.
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audioguru Posted - Mar 08 2014 : 09:11:23 AM
The datasheets show that the varicap diodes are completely different. The capacitance of an old BB109 is much lower than the capacitance of a modern BB405B and the ratios are also different. Then it will operate on the wrong radio band and will not be loud enough.

The powerful transmitter is illegal in most countries and it is missing audio pre-emphasis so it will sound bad like an AM radio or like your stereo with its treble tone control turned all the way down.

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