Antenna for Handheld Com

Discussion in 'Avionics and Upgrades' started by AKBill, Oct 13, 2018.

  1. AKBill

    AKBill Pattern Altitude

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    I have been caring a handheld com when I fly for a couple of years. I store it in my flight bag with a headset connected to it. In the event of a com failure or loss of electrical power my thought was just pick up the radio, put the headset on and hit power. I have most of the local frequencies programed so selecting a frequency as simple as pushing one button on the radio.

    At one time I had a loran C navigation in the plane. The antenna for the loran is still installed. My question is can I use that antenna as an external antenna for the handheld? I'm thinking it cant be used because loran used a 100KHZ frequency and our com frequencies are 118 to 137MHZ. Am I correct that I need a new antenna for use with the handheld com.

    Thanks
    Bill B
     
  2. Stewartb

    Stewartb Final Approach

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    Program the tower number into your cell phone. Way easier.
     
  3. AKBill

    AKBill Pattern Altitude

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    Done. Going into non towered fields is another reason I want the handheld set up.
     
  4. Kenny Phillips

    Kenny Phillips Line Up and Wait

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    I don't see any harm in trying ('cuz I'm the guy who fries stuff by trying, but it's a passive antenna, at least on our plane.)
     
  5. Stan Cooper

    Stan Cooper Line Up and Wait

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    Bill, attempting to use the loran antenna for your VHF handheld would result in a very high standing wave ratio (SWR) because of the impedance mismatch between the VHF transceiver and the low frequency resonate loran antenna. This could possibly damage the final amplifier transistor in the handheld transmitter circuit. Replacing the loran antenna with a VHF aviation band resonate antenna won't be expensive and would result in a much more efficient power transfer from the transceiver's transmitter to the antenna, greatly improving both the received signal strength and your transmitted signal.
     
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  6. AKBill

    AKBill Pattern Altitude

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    My thought is that if the antenna is not properly matched to the radio I could damage the handheld com. Don't know if that is true
     
  7. AKBill

    AKBill Pattern Altitude

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    Thanks Stan. Another question, can I tune the antenna to the handheld or do you just use the correct antenna and call it good?
     
  8. Stewartb

    Stewartb Final Approach

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    Have you tested the radio as is? They usually work fine. Especially with a headset adapter.
     
  9. AKBill

    AKBill Pattern Altitude

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    Tested on the ground only. I was thinking I would like at lest a 10 to 15 mile range and I'm not sure how the handheld would work inside the plane with only the small OEM antenna.
     
  10. Kenny Phillips

    Kenny Phillips Line Up and Wait

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    My old ICOM IC-A22 worked fine in a Skyhawk with just a headset adapter; I made an entire test flight with it, from a towered airport to a couple of untowered fields. Easy ten mile range to the towered airport. I think if I ever buy another plane I'll have an external antenna installed, just in case.
     
  11. Stewartb

    Stewartb Final Approach

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    Do you normally fly without a headset?

    Wife gave me a new handheld with a headset adapter but I don’t carry it in the plane unless I don’t trust the radio, so it’s been flying exactly one time, for the first flight. I already had a handheld that I never use, but she meant well.
     
  12. wilkersk

    wilkersk Cleared for Takeoff

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    You can buy a 2 meter whip antenna for around $40 online that will replace your rubber ducky and work much better. That Loran antenna is nav antenna tuned to receive VLF frequencies at 90-110khz. VHF frequencies are from 108 -137Mhz. I suspect Stan is right that the impedance mismatch would be too great. You'd fry the transmitter with much use at all, and your effective power out would probably be less than with the rubber ducky.

    I use a 2 meter whip antenna on my handheld as my primary radio. Judging from my radio checks, and the garbled static I receive from others, I think my little handheld works as good or better than a lot of panel mounted radios. the trick is realizing that com antennas are vertically polarized. Keep your handheld as vertical as possible to get the best range.
     
    Last edited: Oct 13, 2018
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  13. AKBill

    AKBill Pattern Altitude

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    I fly with a headset. The reason I have the handheld set up with its own headset is for a quick transition between the panel mounted radios and the handheld. No fooling around unplugging and plugging headsets.

    I also count the handheld as part of my survival equipment.
     
  14. Stan Cooper

    Stan Cooper Line Up and Wait

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    Bill, yes you could use an antenna tuner between the loran antenna and the handheld to get a better match, but it would still be a far from optimal configuration because the resonate frequency of the loran antenna is so much different than a properly cut quarter wavelength VHF whip.

    https://www.aircraftspruce.com/catalog/avpages/av534.php?clickkey=153322
     
  15. AKBill

    AKBill Pattern Altitude

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    Thanks Stan
     
  16. weirdjim

    weirdjim En-Route

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    No, you can NOT use the Loran antenna, no matter what sort of matching network you put in the line. In between the coax at the panel and the antenna is an electronic matching amplifier to boost the tiny Loran signal from the antenna down some coax that would just not work. Sometimes that antenna is an external small mini-box and sometimes it is built into the base of the antenna itself.

    Most of the Loran antennas used the same bolt pattern and connector hole location as a standard aircraft whip. If you don't want to buy a new com whip antenna you can get one for a few bucks from most aircraft boneyards.

    If you DO decide to fire the handheld into the coax directly, start saving your money for either a handheld fix or a new handheld, your choice.

    Jim
     
  17. Lachlan

    Lachlan Pattern Altitude

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    Interested in donating one?
     
  18. Stan Cooper

    Stan Cooper Line Up and Wait

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    Good point, Jim. The loran antenna is receive only and has a receive amp in-line. Thanks. Getting a VHF whip from a boneyard will save some $$$.
     
  19. Palmpilot

    Palmpilot Touchdown! Greaser!

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    For renters like me, holding the handheld up to whichever window is toward the station you're trying to talk to may help. Also, it should be held with the antenna oriented vertically for com frequencies, vs. horizontally for VOR frequencies.
     
  20. AKBill

    AKBill Pattern Altitude

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    Thanks Jim, I'll just get a new Com antenna