Hello guys...

Check out the stereo FM receiver I made with the hard to find TEA5711 AM/FM receiver IC... Here's the link:

http://www.midcenturyradios.com/HM-FM-Stereo.html

Let me know what you think...

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It looks good but where's the schematic?

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I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

Just added the schematic at the bottom... Cheers

 

The TEA5711 IC is a real AM-FM stereo tuner.
Its performance Is not good, about the same as my cheap 18 years old Sony AM-FM Walkman radio but is better than a cheap clock radio.

The datasheet has the same circuit as in the link and also has a good pcb design but it includes AM.

The link has a negative schematic that I changed to a positive one.

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Uncle $crooge

 

The TEA5711 IC is a real AM-FM stereo tuner.
Its performance Is not good, about the same as my cheap 18 years old Sony AM-FM stereo Walkman radio but is a little better than a cheap clock radio.

The datasheet has the same circuit as in the link and also has a good pcb design but it includes AM.

The link has a negative schematic that I changed to a positive one.

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Uncle $crooge

 

The performance of my receiver, and hence the TEA5711 is very good. I built the receiver, and tested it. I am in Beirut and receiving good stereo transmissions all the way from Cyprus, 240km/150miles away. the AFC functions good and locks on stations well. The AFC level can be increased/decreased by decreasing/increasing the value of the capacitor at pin 20 of the 5711. Adjacent chanel selectivity depends on the selection of the two 10.7Mhz filters, which in my receiver plug in sockets. I tested filters from 280Khz to 150Khz band width, and settled on the 150Khz with excellent selectivity. I tried a filter in place of the discriminator at pin 5, like Patrick Cambre did in his receiver, the sound was awful, a ceramic discriminator should be used, no questions asked. I used 1uF electrolytic capacitors at pins 2 and 3 instead of the suggested 0.1uF in the application circuit and got better low frequency audio response.

As far as the circuit I used, it is the application circuit in the TEA5711 data sheet, as I have mentioned on my website.

 

The stereo channel separation of 30dB of the TEA5711 might be low compared to that of dedicated stereo decoder IC's, which is on the order of 40 to 45 dB. Still, it sounds very good, and I can't tell the difference when I compare it with my homemade stereo MPX decoder with 45dB separation.

 

The TEA5711 FM RF input is not tuned and does not have AGC which is exactly like my cheap Sony Walkman. Therefore my Walkman is overloaded by strong local stations which causes them to be smeared all over the dial unless I switch on the RF attenuator.

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Uncle $crooge

 

The AGC won't mae any difference with FM (that's the whole point of FM), it's only important with AM.

__________________

I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

Afraid not - in some ways it's even more important for FM, as FM radios quite often have a wideband frontend (AM are sharply tuned). So while AGC isn't used on FM to keep the volume constant, it is used to turn down the gain of the frontend to prevent overload under strong signal conditions.

Notice that car radios often have a local/distant button on the front, which manually does the same thing.

But certainly most FM radios won't have such AGC, only top quality ones.

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The TDA7513 is a pretty good AM-FM stereo tuner that has 80 pins. It has AGC on its FM RF amplifier so that it is not overloaded by strong local stations.

My cheap Sony Walkman FM stereo radio does not have AGC for its RF amplifier so local stations smear all over the dial when its local-distant switch is set to distant in the city.

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Uncle $crooge

 

The front end is broadly tuned, not untuned. The 5711 has distributed IF gain and good strong signal behavior of 500 mV, wich is adequate in most situations. I don't know if it has a limiter before the detector, in which case AGC is not required. In any case, We have a number of very strong FM stations in my area, and none of them are creating ghosts on the dial. All in all, my receiver has very good sensitivity, selectivity and strong signal behaviour. We can debate this forever, but I built it, aligned it and tested it, and these are the facts.

 

I was looking at some FM stereo threads... this is what audioguru said about Patrick Cambre's radio, which uses a TEA5711T IC (T is the surface mount type, I used the SDIP type):

"PS. The Philips IC that Patrick recently used makes a "real" radio. It isn't the same one as in the cheap ones."

Thanks audioguru. I rest my case

 

Hi RadioMate,
Before he made the TEA5711 real radio, Patrick Cambre made the Radio Shack Special which is a regenerative one transistor "radio" that has an AM detector that detects an FM station by "slope detection" (with lots of distortion) when it is tuned to one side of the station. The regenerative circuit has a regeneration control that applied enough positive feedback for it to work. Its bandwidth is determined by signal strength and it overloads easily.

The original (obsolete) version of The Radio Shack Special radio is in the projects section of Electronics-Lab. The improved version is called the RSS when you look for Radio Shack Special in Google.
The TEA5711 IC is much better than Patrick's one transistor "radio".

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Uncle $crooge

 

Hi audioguru,
I've been making radios since I was 14 or so, I am 48 now You can look at some of the radios I've made throughout the years here:
http://www.midcenturyradios.com/Radios-HM.html

I built my first superregenerative circuit years ago from a kit I got in France. Learned a lot from it and beat it to death trying to improve it... then I made more superregens until I had my fill.. they are nice circuits, sensitive, low selectivity, with a very annoying squeal if the station is transmitting in stereo. I tried Patrick's superregen, but I added an audio preamp trany and a power amp IC (LM386).. on par with most superregens.. slope detection, and it overloads badly on strong stations, so I collapse the telescopic antenna!

It's an understatement to say the TEA5711 is better than a one trany radio. I am not claiming it is the best FM IC around, but I tested it thoroughly, and it deserves more credit than you have given it in your text above.. I don't work for Philips but the chip really performs well for its intended purpose.. take it from me, high selectivity with the right choice of filters, very good sensitivity (am listening to stations 150 miles away), and it doesn't overload on strong stations (must be a limiter circuit inside!), very good AFC and stereo separation also. I was skeptical the radio would perform so well, but it did, and am using it quite a lot and plan to make a more compact version.

Thanks for all your feedback.. let me know what you think of my work at the above link. Cheers.