I get a few emails each week asking for a recommendation, and it's hard to go wrong with one (or both!) of these time honored gems. Each inexpensive transmitter kit is simple to assemble and comes with an excellent assembly manual that will help you learn about the technology while putting together a set up that will provide hours of fun.
VEC-1290K Kit, AM Radio Transmitter with Antenna Tuner
"The VEC-1290K is easily setup to broadcast in the AM broadcast band between 540 and 1710 kHz. Accepts audio from standard line-level or microphone-level sources. Delivers good modulation depth and linearity. Features a professional quality epoxy PC board, with solder mask and silkscreened parts legend to make assembly a breeze!" Can be operated under Part 15 of the FCC rules with a 3 meter (9'8") antenna and a power supply input equal to or less than 100 mW. The assembly manual is linked from the product page, and you can read a review here and another review here.
CK108 Kit - Universal FM Transmitter with Mic and Line Inputs
"The CK108 offers an FM transmitter that provides both a built-in sensitive microphone and an RCA jack for line input. In the line mode, it can be easily connected to any audio source to broadcast the audio signal to any FM receiver within its range. 6V DC or 4 x “AA” size batteries, frequency adjustable from 88 to 108 MHz. Low power, can be operated under Part 15 of the FCC rules with a short antenna." Order Page Here, there is a review here, and for more in depth info, see the Set-Up Manual, here.
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