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Radiocommunications

Home Squelch on FM receiver TA7613AP / TA2003P

jonnhy220

hace 5 años

Hello community! I am making a fm receiver in 112 mhz where there are no communications, to generate a short range tranceptor (no more than 50 meters) and I will use as a receiver the TA7613AP or TA2003P that have good quality in the radios in which the I saw installed, but my problem is that I don't have a squelch mute circuit that allows me to complete my project that will lead to other projects. These 2 integrated that I chose have their corresponding AGC that, from what I saw in other types of receivers, can be used to incorporate a squelch system. Of course I would appreciate any suggestion or data about it!

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ricbevi

17.055

hace 5 años

The mute system for FM, works on the basis that when a modulated carrier appears, the received noise ("frying" or white noise) decreases. It is diametrically opposed to how an AGC (automatic gain control) works that detects the presence of a strong signal to lower the intensity of the receiver in general so that it does not saturate / distort. First you must define what type of modulation you will use to emit / receive signals and based on that you can think of some method of silencing the output that minimally alters the signals since no system is safe for the received signal because it takes some time to react .

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jonnhy220

hace 5 años

The idea is to modulate it in amplitude and the consultation is based on air band receivers such as ebay kits but with elements that I can get here in capital, without having to depend on an import. In several diagrams they use 2 operational LM358 but I have no information reliable as is the final result in operation.

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ricbevi

17.055

hace 5 años

There is no silencer that works "well" in AM because any noise triggers it. I don't know what circuit it is since the LM358 is a very common OAMP and can be used for anything. Remember that Yoreparo is an International and Capital depends on where you are. The only thing that uses AM in high frequency is aeronautics and I suppose it is because of the backwards compatibility and the possibility of emitting interrupted carrier (CW) with a pair of cables as manipulator or with the microphone button.

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jonnhy220

hace 5 años

The circuit where I took the idea is based on this commercial product. https://es.aliexpress.com/item/32608332857.html
I live in Buenos Aires Capital Federal so getting variety in components is usually complicated and the integrated ones that I can get for my project are the ones published. I appreciate all the info published and what you can give me!

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ricbevi

17.055

hace 5 años

If you don't find some electronics in Buenos Aires Capital, forget about finding it in another part of the country. I buy what I need there and I'm 500km away. I don't know what you want, if you experiment, it makes the silencing system that is in that scheme and experimental to see how you make it work with the TA7613AP or TA2003P. The other is that you assemble that receiver that appears there and you don't have to experience anything else when you put it together. All these materials are obtained in Capital.

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jonnhy220

hace 5 años

Ricbevi, the idea is what is detailed in the statement, using any of those 2 integrated that I have and of which its performance is well + a squelch circuit that I can add and that has been tested by some forista, different from the receiver of ebay since I do not want to exercise, but for the purpose already described. I appreciate your suggestion of copying the ebay map but it has already been tested without results.

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ricbevi

17.055

hace 5 años

Ready ... Good luck with the search.

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jonnhy220

hace 5 años

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hace 5 años

I thank youtuber Nicolás Bacheta for sharing me diagrams of his homemade squelch project. It is based on the use of AGC pins in the integrated ones that I will use (TA2003P-TA7613) from where you can take signals between 0.5 and 2 volts to command a BC548 NPN that operates as a key for a micro relay, which puts the signal present in the volume potentiometer to ground, enabling it only in the presence of a received signal.

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