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    Rx and crystals

    Iv seen some selling their 29mhz channel...how well is this in terms of interference and usage on planes/heli? cos most of the time i notice 35mhz..40mhz..and 72mhz...do we need to use the same brands of crystals with the tx/rx??

    #2
    Originally posted by ofna
    Iv seen some selling their 29mhz channel...how well is this in terms of interference and usage on planes/heli? cos most of the time i notice 35mhz..40mhz..and 72mhz...do we need to use the same brands of crystals with the tx/rx??
    My 2 cents, not an expert, but from the "research" I had done so far...

    29mhz or 72mhz doesn't tell a thing about interference. It is just a band. It is like Class95 and Zoo 101.6, it is just a different channel, you cannot say which is a better broadcast freq. But I believe 72mhz is a dedicated rc aircraft band (or is it 40mhz), which will reduce the chances of freq traffic congestion.

    Thus the questions should be; is it easy to buy 29mhz Tx/Rx?
    You can get Tx of all bands, but it seemed that only Futaba and JR has 29mhz, which is the more "up market" brand of Tx.
    You can also find 29mhz Rx, if you stick with the original brands Rx, which are usually the full range larger Rx package. But when it come to the feather or micro receivers for smaller birds, it seems that there is no body making 29mhz other than Feigao. As for the rest of the band, 35, 40 & 72, you can find a mind boggling micro Rx available in the market (supposed to be "for export only" ) here in Singapore.

    The reason for such is simple, those 3 higher freq belongs to the American, UK and Japan legal freq, and thus, the market is bigger.

    So, if you want a lot of choice, don't go for 29. But if you want legal freq, then 29. Maybe it is a consolation to say that hitec will be releasing a 29mhz micro Rx very soon.

    The rule of thumb we see so far regarding crystal, brand A Tx using brand A crystal, brand B Rx use branb B crystal, and you will not go wrong.
    SonicBoom

    Comment


      #3
      29mhz

      29mhz for r/c car also?

      Comment


        #4
        Originally posted by ofna
        29mhz for r/c car also?
        No, I think its for aircraft only.


        From http://web.singnet.com.sg/%7Escl5062p/Ts_9.htm

        Permitted Frequency
        in (MHz) & Channel
        Allocation Type of Equipment Output Power (ERP) or Field Strength in
        dB(m V/m)

        Group A
        Channel
        1. 26.995
        2. 27.045
        3. 27.095
        4. 27.145
        5. 27.195
        6. 27.245 For recreation use:
        a) Remote control of aircraft
        and glider models;
        b) Remote control of boat and
        car models; and
        c) Remote control of garage
        doors, camera and toys. a) 500 mWatt
        Not exempted from
        licensing.
        b) Less than 65 dBm V/m @ 10 metres
        Exempted from
        licensing.

        Group B
        Channel

        1. 29.725
        2. 29.750
        3. 29.775
        4. 29.800
        5. 29.825
        6. 29.850
        7. 29.875
        8. 29.900
        9. 29.925
        10. 29.950
        11. 29.975
        12. 30.000 For recreation use:
        a) Remote control of aircraft
        and glider models. 500 mWatt

        Not exempted from
        licensing.

        Group C
        Channel
        1. 29.875
        2. 29.900
        3. 29.925
        4. 29.950
        5. 29.975
        6. 30.000 For non-recreational use :
        a) Radio telemetry devices, data
        (one way)
        b) Fire & security alarm systems
        c) Remote control of machines
        included 500 mWatt

        Not exempted from
        licensing.

        Group D
        Channel
        1. 170.275
        2. 170.375
        3. 173.575
        4. 173.675
        1. 451.750
        2. 452.000
        3. 452.050
        4. 452.325 or non-recreational use:
        a) Remote control of cranes
        & loading arms.

        1 Watt
        Not exempted from
        licensing.

        Comment


          #5
          Hmm...

          hi guys.need to know.For channel and Frequency what is really the difference...
          I have a crystal but and its stated :
          85 Tx FM 40.850 Type 40-1


          What does the individual colour means/???

          Comment


            #6
            Originally posted by MK3D
            hi guys.need to know.For channel and Frequency what is really the difference...
            I have a crystal but and its stated :
            85 Tx FM 40.850 Type 40-1


            What does the individual colour means/???
            "85" means channel 85
            "Tx Fm 40.850" For transmiter, Freq modulation and exact freq.
            "type 40-1" 40mhz band, single conversion.

            Comment


              #7
              More info on crystal

              Originally posted by X34
              "85" means channel 85
              "Tx Fm 40.850" For transmiter, Freq modulation and exact freq.
              "type 40-1" 40mhz band, single conversion.

              How about type 40-6 or 40-12?

              Where can I find more info on the crystal used and their code?

              Thanks

              Comment

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