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Thread: ELT on Expermentals

  1. #21
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    Default Re: ELT on Expermentals

    Timberwolf,

    I agree for the most part and am not trying to create an argument. My info is not off of any wiki - I know there is no standard for transmission wattage. I also know that all 406 ELT's that I've ever seen and I think I've worked with all of them - transmit at 5 watts. I also know all 121.5's transmit at between 75 and 100 milliwatts for the same reason. Whether there is a standard for either is a mute point - that is simply how they were/are all designed.

    Also, to clarify, I never said they transmitted voice from a 121.5 ELT, I said aircraft primarily monitor voice on 121.5 - as it is also (and primarily now) an emergency voice channel.

  2. #22
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    Default Re: ELT on Expermentals

    Any ELT is worthless without the antenna. I purchased the unit with a small portable antenna available. I mounted it in a location that I could reach as long I have one good arm.

    I plan to do the same in my kitfox.

  3. #23
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    Default Re: ELT on Expermentals

    And in case you are interested in an independent comparison, here is the info from NOAA/SARSAT (not my opinion):http://www.sarsat.noaa.gov/406vs121.pdf

    Towards the bottom .1 watts which equals 100 milliwatts.

  4. #24
    Senior Member Dorsal's Avatar
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    Default Re: ELT on Expermentals

    Quote Originally Posted by Danzer1 View Post
    All 406's transmit at 5 watts - 50 times the power and a hell of a lot more range.
    Just as a point of reference (my RF is a little rusty but I believe the following to be correct);

    Range gets worse at higher frequencies 20log(f2/f1) so 406 MHZ has ~ 1/10 the range at the same power as 121.5 MHZ. Power increases range with the following relationship 10log(p2/p1) so 5 Watts @ 406 MHZ has a little more than twice the range of 100 milliwatts @ 121.5 MHZ (this does not take into account differences in antenna gain).

    Other than that I agree with your sentiments on 406 and will eventually change over. The only reason I haven't yet is, like John P, my 121.5 was free and I don't fly over any particularly remote areas.
    Last edited by Dorsal; 11-07-2014 at 01:53 PM.
    Dorsal ~~^~~
    Series 7 - Tri-Gear
    912 ULS Warp Drive

  5. #25

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    Default Re: ELT on Expermentals

    Guess I'll be going with the 406 on a new built. At the speed this project has been going the 121.5 will be history. The knowledge share is fantastic. There are some smart folks out there.

  6. #26

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    Default Re: ELT on Expermentals

    I guess AA spends a little more money on radios. At UAL we only had two VHF receivers. We had to put one in Santa Monica bay before the company would spring for a standby attitude indicator

    [quote=jtpitkin06;44315]I flew the last 23 of my 38 year career with AA. #2 com was used for clearance delivery, ATIS and ramp control when on the ground. In the air it was almost always monitoring on 121.5. There was no need to monitor ARINC frequencies as the ACARS would do that for you on a third VHF receiver
    Chuck

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