Before you get too carried away switch to CW best to lengthen the sweep sweep to several seconds on Dahasheet to avoid being confused by the analysers sweep fly-back and have a look at the output on the spectrum analyser. Finally check the value using a network analyser and adjust accordingly. You can use other transistor as 2SC and get much more output power. Another advantage of the chosen constructional technique is that it correctly aligns the device leads with the top face of the circuit board. F1 can be substituted with a coil as L4, but in my test I found that the ferrite pearls gave best performances.

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The above FM transmitter design is a result of many hours of testing and tweaking. We are happy to announce that this goal and expectations have been met and even exceeded.

The transmitter can work from a single 1. It can also be supplied from two 1. This is mainly due to a use of high quality 3. Tunable RF coils are ideal for precise frequency tuning because their magnet wire is halfway embedded within the plastic, which minimizes frequency drifts.

Regular air coils are not preferred for professional broadcasting because the coil expands and contracts with temperature changes. Another quality of the presented BA transmitter is a crystal clear stereo sound and improved sound separation. There are several factors that account for improved sound quality and a separation. First reason is the use of 38 KHz crystal which provides rock solid frequency for stereo encoder.

Another reason is the use of two 1nF decoupling capacitors one for BA chip and another for 3. These capacitors have to be as close as possible to a BA chip and a variable coil because this will GREATLY improve the sound quality, sound separation and even frequency stability as well.

What they do is filter out the noise in the incoming DC voltage. If the noise enters BA chip stereo generator will include it in a transmitted sound affecting both the sound and multiplex signal that is responsible for generation of the clear stereo signal.

If that noise enters it will also be included in a generation of subcarrier frequency affecting the frequency stability.

Most people are not aware of how important this is and might place them in a wrong location, away from the target components which provides no use, or worse decide not to use these capacitors at all. It is recommended that ground plane should always be used in circuits that deal with higher frequencies. Frequently Asked Questions This is list of answers to questions that I have received through an e-mail so far. Range of the transmitter depends on many factors. What can i do to reduce an output power?

Supply the transmitter with just 1. This is possible but keep in mind that frequency stability will be decreased with temperature drifts. How can frequency of the BA transmitter be controlled with a varicap diode?








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