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Above 108MHz with FM radio (or other)?

Discussion in 'Electronic Basics' started by Michael J., Dec 10, 2004.

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  1. Dbowey

    Dbowey Guest

    Clarence posted:

    Actually your wrong, you just can't admit it!
    Pitiful attempted insult aside, you ARE acting childishly!
    Stamp foot and cry loudly. No one cares!
    Your language skill level is apparently a bit low, so you're screwed-up.

    Why do you believe that just because you and others are incapable of using
    words correctly (mis-spelling and mis-using), that general usage and defined
    spelling will migrate to that low level? I believe that is wishful thinking on
    your part, and is indicative of a lazy mind.
     
  2. Another way is to mix the antenna signal with a frequency which results
    in a mix-product frequency you can receive with a normal FM receiver.

    Connect a signal generator, or a home built oscillator, to the antenna,
    set the oscillator to 30 MHz.

    A signal of 130 MHz coming in to the antenna will be mixed with the 30
    MHz from the oscillator and produce a 100 MHz signal and a 160 MHz
    signal. The 100 MHz signal will be recieved by the radio as if it was a
    normal FM station.

    When signals of different frequencies are mixed you get two resulting
    frequencies, the sum and the difference between the two frequencies.
     
  3. YD

    YD Guest

    I've modified El Cheapo FM receivers by simply removing the caps
    parallel to the tuning caps. Takes a bit of tweaking the trimmers and
    coils but I've been able to listen in on both aviation and police
    bands. Not very sensitive but it works.

    - YD.
     
  4. You're clueless and don't know what you're talking about.
     
  5. Clarence

    Clarence Guest

    Not being qualified to speak for anyone but himself,
    and doing rather poorly at his attempts to avoid a tantrum,
    "Dbowey" contributed nothing of value to the thread.
     
  6. John Fields

    John Fields Guest

    ---
    Your "point" being what? That as more and more people embrace English
    those of us who are native English speakers will understand them less
    and less?
    ---
    ---
    That's because more and more people aroung the world are discovering
    newsgroups and are realizing that to participate in most, they'll need
    to do as the Romans do. But, regarding your statement, so what? You
    may have noticed that most of the posters with English as a second or
    third language who post to this group are quite conscious of the fact
    that they use the language differently from native English speaking
    participants and are not at all adverse to taking instruction in the
    proper use of the language.
    ---
    ---
    No, we won't. Since non-native speakers will approach English from a
    position of ignorance, _they_ will be obligated to learn English the
    way it's used by English speaking persons, and for clarification of
    poorly or misunderstood meaning will _have_ to refer to source
    material, such as dictionaries, written by authorities on the matter.
    Such being the case, the language will evolve, as it always has, but
    its proper use, technically, will remain unquestioned. Somehow, you
    seem to think that this great pool of non-native English speakers is
    going to rise up, en masse, with an identical set of preconceived
    notions about how the language should be used and that those of us who
    use the language will be forced to bend to accept those notions as
    proper in order to communicate. Get over yourself.
    ---
    ---
    It's never been a question of enforced dominance, it's been a question
    of the availability of local VS imported programming. What's happened
    is that as the third world has become more affluent (largely through
    the efforts of the native English-speaking world I might add), time
    and talent has become available for the production and broadcasting of
    local programming instead of the growing of food. So now, Baywatch is
    still on at 8PM, but instead of dead air from 9PM until noon,
    "Diverciones Bobosas" has the half hour from 9 'til 9:30...
     
  7. John Fields

    John Fields Guest

     
  8. John Fields

    John Fields Guest

     
  9. Don Bruder

    Don Bruder Guest

    Until they activate the killfile...
     
  10. Clarence

    Clarence Guest

    Not qualified to speak for anyone but himself,
    "Don Bruder" contributed nothing of value to the thread.
     
  11. Steve Evans

    Steve Evans Guest

    "Dbowey" has never conrtibuted anything of value to _anything_ from
    what i can gather.
     
  12. Steve Evans

    Steve Evans Guest

    not normally, but Roger's proposing something rather _ab_normal!
     
  13. John Fields

    John Fields Guest

    ---
    If you heterodyne a couple of signals, f1 and f2, what you'll get out
    of the mixer will be f1, f2, f1+f2, and f1-f2, so the original signals
    _do_ remain; I was chiding Roger for his omission and for his little
    grammatical error in the light of his recent native-English
    speaker/America-bashing outbreak. Also, his proposal about mixing
    with a second local oscillator was far from abnormal, it's done all
    the time and it's called double conversion, as I recall.
     
  14. Dbowey

    Dbowey Guest

    Steve Evans displayed his ignorance again, with:

    "Dbowey" has never conrtibuted anything of value to _anything_ from
    what i can gather.
    I recall pointing out, a time or two, that you are an ignorant ass. That is a
    big conrtibution, and I think, even a good contribution.
     
  15. Yes they do, but they are of no significance in this case, the sum- or
    difference-signal is what interests us after the mixing.
    If you look through radio amateur and DX magazines you will find ads for
    small converter boxes you connect to the antenna to listen to frequencies
    outside the radio's built-in bands. The box only contains a simple, but
    stable, oscillator.

    Theoretically, someone might say that the mixing of signals have to be
    done in a non-linear component, like a diode or a transistor, and there
    is no such component in the antenna.

    But there usually is a non-linear component in the input stage of the
    radio, and that's where the actual mixing takes place.



    --
    Roger J.

    ....what is really abnormal in the human society is what needs a lot of
    training and violence to be "created", the male mind, for example.
    that is what creationism is really about, the "creation" of the eternal
    love and the holy matrimony, the holy ghost and the holy wrath, the
    institution of the church and the mental training of young girls to
    become convincing love machines..
    ...this leads to a dualistic society, heaven and earth, where a lot of
    determinism, based on anger, is needed to have free will in social
    life.. it will only cost you your soul and your sound judgement, but
    what do you care about the soul, when love feels like a powerful drug.
    Anger plus conviction becomes the God state of mind.
    Holy cows are very convincing, and anger is what the tv is full of every night..
    ...sometimes the gods fail in "creating" a man, because he refuses to become
    angry, then they crucify him and kill him instead..
     
  16. Clarence

    Clarence Guest

    Childish retort noted.
    Must be trying to set a record!
     
  17. Dbowey

    Dbowey Guest

    Clarence,

    I'm glad you enjoyed it.

    That's one more happy customer.
     
  18. This is "basics," right? I think it's worthwhile to point out the
    difference between heterodyning and just plain old ordinary "mixing". If
    you just send two signals through a circuit, if the circuit is linear, you
    simply get the two input frequencies in the output. There has to be some
    sort of nonlinearity to cause them to modulate each other to cause there
    to be sum and difference frequencies. I'd think that this kind of spoils
    the idea of just setting a 30 MHz oscillator next to your antenna, and
    expecting to pick up 160 MHz transmissions at 100 MHz on your FM tuner.

    The beat frequencies you hear when you're calibrating your short-wave
    receiver actually get produced in the detector, which the tutorials always
    show as just a diode.

    Plus, you have to have some selectivity at the frequency of interest, in
    this case, 160 MHz, and the mixing has to be done in a circuit that's
    designed to cause them to heterodyne against each other. Just an
    ordinary diode would work, if the 160 MHz signal swamps out everything
    else at your location. Or maybe if the 30 MHz drives the RF amp or first
    mixer into saturation every half-cycle. That'd be pretty non-linear.

    Thanks!
    Rich
     
  19. I exclude anything from clarence, so I'm luckily never bothered with any of it
    except when others follow up. Oh, well. So I missed some of the exchange until
    now.

    Regarding this exchange, Steve, I can tell you that when I was wrestling with
    ideas for a phone indicator that relied on the phone line for power, dbowey was
    very well informed on the subject and told me some things I was wrong in
    assuming about it. More, he took the time and trouble to drive quite some
    distance and meet me personally to help me further by giving me an original of
    the appropriate specifications I needed to read. I still have those on my shelf
    and I've spent time going though the parts I needed to read.

    You don't get help like that, often, and he provided something that really isn't
    all that easy to go find, either. He offered without my asking and I think he's
    very generous when someone shows even a little effort. And that's as much as
    any of us deserve to hope for, really.

    Your comment is just malicious.

    Jon
     
  20. John Fields

    John Fields Guest

    ---
    You seem to have neglected to point out that in the context of _this_
    thread, and in generally accepted RF terminology, 'mixing' refers to a
    process which results in previously nonesistent sidebands being
    generated. Were audio recording being discussed in this thread, then
    'mixing' might, in that context, refer to the algebraic summation of
    various signals, not to the multiplication required for modulation.
    ---
    ---
    Then you'd think wrong, since all that's necessary for the sidebands
    to be generated is for the gain of the front end to be made to vary by
    the new 30MHz local oscillator.

    In addition, it wasn't a 160MHz carrier which was being discussed, it
    was 130MHz.

    From the OP:

    "I was wondering if there is any type of receiver I can find/purchase
    that would be
    capable of tuning above the FM band, like from say 100 to 130 MHz."

    And Roger's reply:

    "Connect a signal generator, or a home built oscillator, to the
    antenna, set the oscillator to 30 MHz.

    A signal of 130 MHz coming in to the antenna will be mixed with the 30
    MHz from the oscillator and produce a 100 MHz signal and a 160 MHz
    signal. The 100 MHz signal will be recieved by the radio as if it was
    a
    normal FM station."

    which was correct.
    ---
    ---
    So what? All that proves is that two carriers separated in frequency
    by the frequency of the beat note are being allowed to propagate all
    the way the through the RF and IF chain to the detector, where they
    mix, or that a signal is being injected somewhere which eventually
    yields the beat note. For instance, a CW carrier generating a 455kHz
    IF will generate a 1kHz beat note if a 456kHz signal is injected into
    the IF.
    ---
    ---
    You need no selectivity, all you need is for the new 30MHz local
    oscillator to change the gain of the front end so that it looks like a
    mixer and beats the 130MHz carrier down to 100MHz. From that point
    on, the RF section of the radio looks like a new IF and the radio
    becomes, effectively a double conversion superhet with a wide-open
    front end.
     
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