DIY Portable FM Radio (Part 1) Tuner Front End

It is started when I have spare time in home and try to figure out what is on my storage box. I usually throw my ex. DIY project to this big cardboard box. I think I will not use it, or I just explore something related to electronic device then put it in the box for future need.

Sometimes like this day, I open up again the box and it is kind of nostalgic moments. So this is what I found.

By looking this board, I am pretty sure this is a radio module. Perhaps it is from old radio kit or anything else. So I figure it out and found the Blue IFT coil is absolutely for a FM radio.

Then I taken out the IC, it is show the TA7358P. It is absolutely for the front end FM radio as per datasheet from Toshiba.

If you don't want to read all this post, then this is the full schematic of the FM radio front end.

Making a radio is something that anyone will enter before going deeper to this DIY audio hobby. Just like me, I started make my own radio when I was twelve. And it is not working. I trying many times even I have to stop buying school lunch for saving money. I remember after several times trying, I succeed make my first MW radio using YS414. Then I jump to make FM radio using several transistor. Again it is a failed project. Make radio is hard, but it is tempting.

Back to the schematic, you will need the explanation for the circuit. The IC pin 1 is the antenna input after the 10pF capacitor. You need to pay attention for the IC pin 3 is marked 'A'. This pin should connected together to other 'A' marked after the L2 Same with the marked 'B' should be connected together with the IC pin 8.

Please pay attention to the input-output of this module:
1. The AFC out contain radio signal is from the blue IFT and IC pin 6.
2. The radio tuning pin is for the voltage variable sensing tuning. This pin will function as radio tuning frequency.
3. Then the 3 volt is for voltage in. The 68 ohm can be adjusted up to 2k for greater voltage requirement. The default from original board is 1,2 k.
4. The ground is the negative voltage.

The coil is explain as above photo. All coil diameter is about 6 mm and the wire diameter is about 0,4 mm. L1 is 5 turn, L2 & L3 is 4 turn.

As usual, my habit is put all components to the new universal board. It is all point to point connection.

The front end FM radio is now done. Part 2 will be publish soon for the FM modulator. Stay tune:)

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