Optimod 8182a Question

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Thread: Optimod 8182a Question

  1. #1

    Optimod 8182a Question

    I have recently picked up one of these units and am playing around with it at home with a small exciter. I remember reading that there are a number of modifications you can make to internal jumpers etc. that make it operate similar to an 8100a - would anybody have any more information?

    Thanks in advance!

  2. #2
    The 8182A is a TV station audio processor. It has a different preemphasis curve and has a different output scheme than used on broadcast FM.

  3. #3
    General Manager frankberry's Avatar
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    Quote Originally Posted by Kelly A View Post
    The 8182A is a TV station audio processor. It has a different preemphasis curve and has a different output scheme than used on broadcast FM.
    You are only partly correct. The preemphasis curve is the same as for FM. The stereo pilot is 15.734kHz rather than 19kHz for stereo FM. There is DBX processing on the stereo subcarrier while there is no such processing for stereo FM.
    Last edited by frankberry; 08-02-2017 at 10:47 AM.

  4. #4
    Quote Originally Posted by frankberry View Post


    You are only partly correct. The preemphasis curve is the same as for FM. The stereo pilot is 15.734kHz rather than 19kHz for stereo FM. There is DBX processing on the stereo subcarrier while there is no such processing for stereo FM.
    You're right Frank. Forgot about the pilot difference. But I do believe the TV Optimods were shipped with 150 microsecond preemphasis rather than 75.

    Either way, unless one comes out of the monitor jacks with discrete audio and into an FM stereo generator with preemphasis, it's pretty much useless for FM broadcast.

    Oh and one other thing OP: unless you have a LPFM license, you can't just make your own radio station from an exciter and TV audio processor you bought off EBay. That's what's known as illegal.
    Last edited by Kelly A; 08-02-2017 at 06:33 PM.

  5. #5
    Quote Originally Posted by Kelly A View Post
    Oh and one other thing OP: unless you have a LPFM license, you can't just make your own radio station from an exciter and TV audio processor you bought off EBay. That's what's known as illegal.
    Really? I had no idea..!

  6. #6
    General Manager frankberry's Avatar
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    Quote Originally Posted by Kelly A View Post
    You're right Frank. Forgot about the pilot difference. But I do believe the TV Optimods were shipped with 150 microsecond preemphasis rather than 75.

    Either way, unless one comes out of the monitor jacks with discrete audio and into an FM stereo generator with preemphasis, it's pretty much useless for FM broadcast.

    Oh and one other thing OP: unless you have a LPFM license, you can't just make your own radio station from an exciter and TV audio processor you bought off EBay. That's what's known as illegal.
    Analog TV preemphasis is the same as FM preemphasis. You may be confusing the deviation. FM deviation is 75kHz. Analog TV deviation is 25kHz. Nowhere in the world is 150 microsecond preemphasis standard.
    In the USA, it's 75 microseconds ... in Europe, it's 50 microseconds.

  7. #7

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    75 us. has been around a long time in the US. Its an easy component change to modify 50us to 75us.

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