Old radios

Discussion in 'Avionics and Upgrades' started by Tom-D, Sep 1, 2018.

  1. Tom-D

    Tom-D Taxi to Parking

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    To train a new student, do you need a radio with the third digit past the decimal point?

    many of the airports now have frequencies that can not be received by many old radios.

    Thoughts?
     
  2. Greg Bockelman

    Greg Bockelman Touchdown! Greaser!

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    Is it a 360 or a 720/760 radio? I am not sure if a 360 channel radio is still legal.

    But...

    I guess the bottom line is that if the radio is legal, one can work around the lack of frequencies.
     
  3. Cap'n Jack

    Cap'n Jack Final Approach

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    Many older radios only display 2 decimal points, the last one is implied. For example:
    118.00 = 118.000
    118.02 = 118.025
    118.05 = 118.050
    118.07= 118.075
    118.10= 118.100
    etc.
    Are you sure you aren't using one of those radios?

    If the plane really has only 360 channels, there are other issues- you may get interference on the frequency you are listening to if someone is is transmitting on an adjacent channel. Transmitting on a 360 channel radio is legal so long as it meets a 30 ppm frequency tolerance, but most don't meet that standard. See: https://www.fcc.gov/wireless/bureau...ion/aviation-radio-services/aircraft-stations.

    The cited reference suggests that isn't easily done:
    I would guess that the radio would be much more difficult to upgrade now.
     
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  4. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    A 360 channel radio is still legal if it meets the frequency tolerance requirements. All 720/760 channel radios do, some 360 do, many 360 don't.

    As CJack points out, it's not the numbers behind the decimal points but whether your radio can tune the 25 KHz channels or not, regardless of whether it uses 2 digits, 3 digits, or just flipping a switch to indicate the odd-numbered channels.
     
  5. bnt83

    bnt83 Final Approach

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    FWIW most newer radios have stuck mic switch protection, preventing stuck mic from blocking a frequency for more than xx seconds.
     
  6. weirdjim

    weirdjim Ejection Handle Pulled

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    I still have FCC PMA for a 2 channel and a 6 channel, so I'm not sure why a 360 wouldn't be legal if it met the frequency accuracy required.
     
  7. Tom-D

    Tom-D Taxi to Parking

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    KX 170-B is a 720 channel radio but has no third digit 000.00 is all that they have,, many of the airports have 000.000 frequencies.
    The CFIs argument was he can't send a student to any airport that has the third digit as their Common traffic freq. or if on a solo cross country if the student has a problem they would be restricted as to where they could divert.
    Most all the weather stations around here are 000.000 type.
     
  8. Tom-D

    Tom-D Taxi to Parking

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    We know the 360s have gone away, this isn't about frequency separation.
     
  9. Pilawt

    Pilawt Final Approach

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    That's what was described in Post #3 above. Dial a KX170/KX175 to 119.62, for example, and it is actually tuned to 119.625. If the second decimal place is a '2' or a '7', then the third decimal place, though not shown on the display, is always a '5'. I'm still using one of those radios.
     
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  10. Tom-D

    Tom-D Taxi to Parking

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    Thanks, I didn't realize that. you can't see it on the dial.
     
  11. Cap'n Jack

    Cap'n Jack Final Approach

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    If that statement above is being shared accurately here, the CFI is giving bad information. A 720 channel radio and pick up anything in the USA. Europe is a different matter, but not pertinent to this discussion. People still learn to fly and solo with a 720 channel radio with only 2 decimal places displayed. Better that the CFI teaches their students about the radio in the planes they fly, and other radios they may encounter, than give poor information.


    The people trying to help you were confused by your original post (requoted below). We figured you weren't talking about the still older 90 channel radios. As mentioned above, the 720 channel radios can work with any USA frequency, and many of them are pretty old now. The bolded part of your question was the part that made us also think you may have been discussing a 360 channel radio.
     
  12. SkyDog58

    SkyDog58 Touchdown! Greaser!

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    Simply amazing.
     
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  13. Tom-D

    Tom-D Taxi to Parking

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    you can tell who the haters are.

    Like I'm your avionics expert.
     
  14. Cap'n Jack

    Cap'n Jack Final Approach

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    Huh?
     
  15. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Nope, while many of the upper channels are marked out for future UNICOM / AWOS use, they do have ATC up on some of them. I've been assigned those channels (ATC even asked me if I could tune that... I pointed out the Navion is old but it has up to date avionics).

    Europe has even gone beyond 760. They are using 8.33Khz spacing.

    Again, incorrect.
     
  16. JScarry

    JScarry Pre-takeoff checklist

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    If I recall correctly, in order to get the .025 and .075 frequencies, you need to pull the smallest knob out and then turn it. Like others have said, the .005 won’t display
     
  17. Pilawt

    Pilawt Final Approach

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    That is true on some radios, but not the KX170/175 series. The small knob just clicks through .00[0], .02[5], .05[0], .07[5], .10[0], .12[5], .15[0], .17[5], ...
     
    Last edited: Sep 1, 2018
  18. Cap'n Jack

    Cap'n Jack Final Approach

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    Thanks for the correction. I actually saw that earlier when looking up the frequency tolerance I mentioned earlier. However, one can certainly still train and solo in a plane that displays only 2 places past the decimal point, and that part of my statement still stands.
    This radio could be bought new, and I presume has 760 channels, but only displays 2 decimal places: http://sarasotaavionics.com/avionics/par200a

    Assuming @Tom-D relayed the conversation accurately, the CFI is still incorrect.

    True, but I doubt the training mentioned in the OP will happen there. I wonder why- they don't have the traffic we do.