Finalized version of Stereo FM Radio Receiver
Finalized version of Stereo FM Radio Receiver

In this project we build CXA1619BS base high performance FM stereo radio receiver using low cost and readily available electronic components. In this design we use CXA1619 as FM radio receiver and BA1320 as FM stereo decoder and LA4108 as power amplifier.

When building the circuit it is highly recommended to build it using the print circuit board (PCB) and take some necessary steps to reduce the effects of external interferences.

In this design we use BA1320 as stereo decode and user can also use BA1330 with this circuit with some less amount of input voltage. (For example: +5V) We use BA1320 for this design because of its low cost, low complexity, higher channel separation and higher availability.

In current design we use LA4108 as power amplifier and it delivers 6W x 2 output power at 8ohm load.

While assembling the circuit make sure to apply suitable heat-sinks to both 7805 voltage regulator and LA4108 power amplifier.

At the testing stages this circuit produces excellent results and fewer amounts of issues in tuning. Anyone can tune this circuit without using signal generator and oscilloscope.

It is recommended to provide 7V to 12V of supply voltage to this circuit and at the testing stages we use 8.0V PSU with this circuit

Assembling Notes


This circuit uses two coils. Most of the times these coils are available in electronic component shops, but some times some uses inform that it is bit difficult to obtain these coils from open market. If both L2 and L3 are not available in market you can build it in home. Coil winding details are listed in below,

  • L2 – 22 S.W.G; 3 ¾ turns; 5mm diameter.
  • L3 – 22 S.W.G; 2 ¾ turns; 5mm diameter.

Please note that these winding details are critical and it directly affects to the performance of the receiver.

For L1 use Orange color FM IF transformer. Pin connections of this IF transformer is illustrated in below.

orange_fm_if.jpg

XFT1 is 3pin 10.75MHz crystal filter and its pin connections are listed in below.

xtf_fm.jpg

You can use any FM Tuning condenser (C7) with this project and some times some of the tuning condensers may not exactly match with the given circuit, then user need to change C8 and C9 capacitors to get the exact performance of the receiver.

Tuning and final adjustments


At the designing stages we try to reduce critical tuning components (e.g: coils, trimmers, IF transformers) as minimum as possible, so most of the times this receiver work successfully when you apply power to it, at first time.

If you need more adjustments please consider following points,

  • To tune the trimmers and IF transformers use plastic or wood screw driver.
  • To change the coils use plastic or glass rod, do not use metal screw drivers.
  • When tuning the receiver place receiver PCB on wood or glass surface.
  • Do not touch the metal spindle of the tuning condenser, use proper plastic knob (dial-drum) to adjust the tuning condenser.
  • Always connect some wire as antenna or telescopic antenna (recommended) to the receiver

Project Related Downloads


Complete circuit diagram of Stereo FM Radio Receiver project

References


CXA1619BS - FM/AM Radio
BA1320 - FM Stereo Multiplexer
LA4108 - 12W x 2 Stereo Power Amplifier