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    Radio receiver from old analogue tuner - some questions, I am preparing for the proje

    Hello,
    I have read about this topic several times, but there is not much info about that.
    I want to use old television ANALOGUE tuner as the FM receiver.
    I am going to try replicate this design:
    Click image for larger version. 

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    As for the start, I have browsed trough my tuners. I have selected only the analogue ones (I don't want to use I2C for now), and then selected only the ones that have pinout description on the metal case. I have looked inside them and wrote down which chips they are using.
    Here they are:




    Click image for larger version. 

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    Tuner SHARP VTSS 6o2
    Chip: IX1018VA
    Pinout:
    1. BU
    2. VT
    3. BH
    4. AGC
    5. BL
    6. AFT
    7. B
    8. IF





    Click image for larger version. 

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    Tuner SHARP VTSS7 S4
    Chip: IX1018VA (same as above)
    Pinout:
    1. BU
    2. VT
    3. BH
    4. AGC
    5. BL
    6. AFT
    7. B
    8. IF




    Click image for larger version. 

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    Tuner SAMSUNG TECC 0985VD 28A 14555437-0 (K)
    Chip: TDA5330T
    Datasheet supply voltage: 12V (max 14V)
    Pinout:
    1. BU
    2. BT (I assume it's VT?)
    3. BH
    4. AGC
    5. BL
    6. AFC (same as AFT?)
    7. BM (same as B?)
    8. IF




    Click image for larger version. 

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    Tuner TDZ-3D 000311
    Chip: TDA5637T
    Datasheet supply voltage: 9V (max 10.5)
    Pinout:
    1. BU
    2. BT (I assume it's VT?)
    3. BH
    4. AGC
    5. BL
    6. AFC (same as AFT?)
    7. BM (same as B?)
    8. IF


    So now, my questions are:
    1. Can anyone find IX1018VA datasheet? I need it for the supply voltage, etc...
    2. What should I do with AFC pin? According to forum Search, it's the Automatic Frequency Correction, but I don't know how to connect that. Do I need to support that in order to get tuner running?
    3. Is there any way to test the TV tuner IF output without attaching SAW filter and other stuff (like TA2003P)?
    4. Is there any way to test the TA2003P module without TV tuner connected? I don't know, maybe put some kind of frequency generator that outputs the intermedeiate frequency of the tuner...
    5. What is this "10.7MHz" part connected to Vr?
    6. Where can I get 10.7MHz Ceramic Discriminator?
    7. And last, are those SAWs okay? I assume that Saw must be for the exact IF Frequency, right?
    Click image for larger version. 

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    Soon I will try to scavenge some more TVs or other equipment, maybe radios... and I will design a PCB for this project in Eagle and of course publish it sources here... so any suggestions and hints are welcome!

    •   Alt9th September 2017, 17:44

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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    I would anticipate very poor performance. The designs seem to be for receiving FM TV sound rather than the broadcast FM band but it might cover those frequencies too.

    1. Tuners like those are often custom made for a particular TV model and the coding on it, and the devices inside it, may be house codes rather than generic parts. However, given that most tuners are designed to work in portable (battery supply) as well as mains supply, they almost all work on a 12V supply.

    2. AFC is used to cancel minor tuning inaccuracy and frequency drift. You don't have to use it. Probably the best way to ignore it is to ground the pin. If you actually want to use the AFC, you need extra circuits to derive a tuning error signal which you feed back that pin.

    3 & 4. Sadly, the module is designed to drive the SAW filter and it would be difficult to replicate one with other components. You can try feeding a signal at about 38.9MHz to pin 1 of the TA2003 top replicate it's output. The signal level should be quite low, only one or two mV.

    5. A standard ceramic 10.7MHz IF filter as use din domestic FM receivers.

    6. Not sure but they are fairly widely used so they shouldn't be too hard to find. They look just like the 10.7MHz IF filter but only have 2 pins, they are not interchangeable!

    7. You would have to confirm their frequency with the data sheet or EPCOS. You can get SAW filters manufactured to your own design so ones salvaged from old equipment could be for anything. For example, they are often used in VCRs at completely different frequencies to the one you want.

    Brian.
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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    I don't know how this schematic is based on but there should be a Band Stop Filter in analogue tuners because FM broadcasting signals are high and they will disturb TV signals.
    Except CATV Tuners because there is Low S-Band just after VHF Band I.So "Any TV Tuner" cannot be used, the Tuner should be for CATV application.

    - - - Updated - - -

    TA2003 is already a FM radio IC, why an additional TV tuner+SAW Filter is used ??? An good and selective LNA then TA2003 will be OK.



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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    Also consider that the tuners outputs are designed to feed a SAW filter so its best to use one but a typical TV SAW filter has a bandwidth of about 6MHz when you really want it to be about 0.2MHz (200KHz) for FM radio reception. The second filter at 10.7MHz helps to some degree but it is quite likely that the wider range of signals passing through the SAW filter have already overloaded the mixer before they reach it.

    I do have a multi-mode VHF/UHF receiver here that uses a TV front end module but it is immediately followed by a chain of tuned LC circuits to sharpen it's bandwidth before further processing.

    Brian.
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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    I got a bit confused, because I tought that "filter" and "resonator" is not the same thing, but the auction name in the store I buy says clearly:
    "10PCS Ceramic Resonators DIP-3 Ceramic filters LT10.7M 3P 10.7MHZ ZTT10.7M ZTT10.7",
    and the picture is such:
    Click image for larger version. 

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    And the discriminator is this:
    Click image for larger version. 

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    Are those the correct parts?

    Also I have checked my SAW filters but they have 5 pins and not 3...
    Click image for larger version. 

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    How should I connect that?



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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    The first picture is of filters. The pins are in:ground:out but they are symetrical so they work equally well if turned 180 degrees.
    The second one is a ceramic resonator.
    The third is a TV SOUND filter, the type you need at the TV tuner output is an IF filter which is different.

    You can get SAW filters for IF in that package but most look like this:
    Click image for larger version. 

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    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.


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    •   Alt10th September 2017, 19:09

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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    So now I am waiting for the shipment of filters and the ceramic resonators, altough I could try finding them in the junk.

    Nevertheless, I have two working CRT TVs at hand... and I wonder if it would be possible to "hack" them to receive the FM radio or anything? I've read that there is some kind of "disable signal if video not present" mechanism in the newer CRTs, is that why they can't pick up anything?



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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    The disable signal is derived from the horizontal sync PLL and its purpose is to mute the audio when no recognizable TV picture is present. It is for killing the background hiss in the absence of a TV signal rather than to stop you picking up radio signals.

    I really think you will be disappointed by the results of this experiment. At best you will pick up a few FM broadcast stations but with poor sensitivity and probably difficulty in tuning them. TV signals are (were) originally AM and occupied a wide bandwidth of several MHz per TV channel so the SAW filter and tuner bandwidth is much wider than you want. Consider that one TV channel would use up half the entire radio broadcast band and you really want to be able to select and individually filter maybe 10 radio stations in the same space.

    Brian.
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    •   Alt13th September 2017, 08:52

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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    Well, I have more than ten different tuners at hand, both analogue and I2C ones, so I tought I might try to find some use for them.
    Most likely I will try anyway, but maybe there is a different use for them?



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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    They are not much use at all I'm afraid. They are too dedicated to one job to be used for other purposes. You can make a crude spectrum analyzer out of an analog tuned one by adding only a few other components but the accuracy would be poor.

    If you want to try that, you need an oscilloscope with an 'X' output (not common on newer models) or at least an oscilloscope with an X-Y plotting mode. Essentially you sweep the tuner across the band by feeding it a ramp waveform on the tuning voltage pin and at the same time feed the voltage to the 'scopes 'X' input so it moves the dot horizontally. That means that as the dot moves from left to right, the tuner sweeps from low to high frequency. Then you amplify and rectify the tuner module output so it produces a voltage proportional the strength of any signal it receives and you feed that voltage to the 'scope 'Y' input. It produces a kind of map of the band showing where the signals are and their relative strengths. This is a screen shot from a spectrum analyzer built in to my receiver:
    Click image for larger version. 

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    The left side is 9.900MHz and the right side is 10.100MHz, the higher the peak, the stronger the signal on that frequency is.
    The peak on the left is a BBC broadcast service to India, the one on the right is a data transmission in some encoded format. I'm not sure what the weaker signals between them are.

    Note that the picture is NOT from a simple receiver like yours or from a TV tuner but it gives an example of what is possible.

    Brian.
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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    I think that my old scope has X-Y mode, but... If I understand correctly, wouldn't be the same thing possible with Arduino and DAC module?
    I mean, I'd use DAC to produce the appropriate tuning voltage from code and then just read the analog output value with ADC_Read and then just output X,Y values by serial to PC where I can easily plot them.



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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    Yes, thats exactly how most systems work but rather than use the ADC directly, they use a logarithmic amplifier stage so it can cover a wider range of signal levels.

    The complications of using something like Arduino are lack of frequency resolution and the speed of the ADC and memory. An oscilloscope gives an immediate visual output with needing to do processing to make a graphical output.

    The resolution problem is because the Arduino will have difficulty producing a precise enough analog voltage. Bear in mind you probably want to produce a voltage in the range 0V - 30V to cover the band and it needs to be selectable in steps of maybe 5mV or less (~6000 steps). That is probably beyond the capability of Arduino PWM and and any DAC you can easily build. You might be able to use I2C to program the tuners but that usually means in large frequency steps so it won't work as well as an analyzer.

    Brian.
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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    Back in the day...before we had access to today's technology there were a number of implementations for making use of TV tuners.

    TV tuner spectrum analyzer.


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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    That's much as I described in post #10. There are probably easier ways to generate a linear ramp since that article was published but the basic theory is unchanged.

    Brian.
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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p




    •   Alt17th September 2017, 04:37

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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    Thats a good link and example of a better solution than the SAW filter method but not there is a serious error in the schematic. The quadrature coil (TBA120) is shown shorted out, it should be a single inductor, if a transformer is used the secondary should be left disconnected. The input coupling is also suspicious, check against the data sheet for proper ways to connect and decouple the bias supply. Note that some copies of 'National Semiconductor' data sheets show the input on pin 4 on their example schematics, it should be pin 14.

    Note that making R3 variable will make it work as a volume control.

    Brian.
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    Re: Radio receiver from old analogue tuner - some questions, I am preparing for the p

    i make a radio form a link.
    hare is it http://www.radioscanner.ru/forum/topic23937.html



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