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  • FL-760 Radio

    Tribe,
    After admiring Mike Rice's radio box I decided to build one like it. I used the FL-760 radio, an Absorbed Glass Mat battery, an a few other sundry parts to come up with a nice rig. The photos mostly speak for themselves. I made the radio box totally self-contained except for an external BNC antenna jack. I also placed an external power jack on the side using a "marine grade" lighter receptacle. This latter locks the marine grade plug in and it can't come out without a quarter turn. Recharge is with a 2 amp smart charger.

    I'm sure if anyone else decides to build a radio box they will customize it. So rather than give a building tutorial, let me tell you what I like and don't like about my setup.

    Likes:
    - Radio is less expensive than most others and very light weight. I know - it is not TSO, but it is not "installed" either.
    - After running the radio for 5 hours in the traffic pattern, I was down to 12.3 volts from a 13.2 volt full charge. I think I could run this rig for a week of flying.
    - Audio is excellent. Power output is just fine - no more complaints about my weak handheld.
    - Controls are easy to use. It has a flip flop. Even the software programming controls are simple.
    - The big digital voltmeter I put in the circuit is Sooooo nice. It doubles as an ammeter.

    Dislikes:
    The squelch knob works only for the radio receiver. The intercom squelch is set by software as either lo, mid, or hi. It requires a lo setting to prevent my noisy cockpit from continuously breaking squelch on the intercom. Once I figured out how to set the software it actually works pretty well - but of course there is only one squelch setting, so if the headsets are not of matched impedance you may have one person having to raise their voice to break squelch on the intercom. Individual squelches such as found on P/S engineering intercoms are really nice, and continuously adjustable squelches are better than my the three setting software - but I am learning to live with it.

    The intercom volume is not settable. You must use the headset volume control to turn down the intercom to a comfortable level and then turn up the radio until you hear it OK.

    When the radio is receiving, the intercom is silenced. When I instruct, I hate the intercom to cut out in the middle of some vital directions to my student. In a busy traffic pattern I have to give short bursts of instruction. However, for non-instructional flights the cut out feature is actually nice... no missed radio calls due to chatty passengers.

    If either PTT is pressed, both headsets go hot mic. Just a gotcha to keep in mind.

    Things I did wrong:

    My radio box is too tall. It is 12 inches tall and I can't get it under my knees. If it were 10 inches tall it would slide under my knees and I could work the rudder without it digging into my calf. It is quite possible to re-arrange the box to make it sit lower, or go with a lower amp-hour battery thus allowing the box to be built more compactly. I could leave off the ammeter shunt and save a little room. I could also mount the battery on edge and off-set the radio to one side.

    I should probably have placed the jacks near the center of the box top so they are not susceptible to thunder thighs.

    So there is a non technical view of the FL-760 compact radio.
    Attached Files
    Last edited by Mark Julicher; 05-28-2012, 18:08.
    Best Regards,
    Mark Julicher

  • #2
    Re: FL-760 Radio

    Nice radio setup!

    Having examined Marks' radio setup in person, I saw several items I liked better than my rig (Marks' workmanship being one). The height is not apparent as an issue, until you fly with it. Mine is about 10" high. I also ran the headphone and mic jacks out the sides, and that has been useful to keep the top around the radio clear.

    I like the nice Voltmeter on Marks', mine was built into the radio, so I did not add it externally. The built-in intercom is a very nice , compact feature, but you are dependent on features delivered with the radio/intercom combination. I considered taking a 2 place Sigtronics or Pilot intercom apart for the circuitry and intercom jacks, and that might have saved some soldering, because figuring out the wiring of the intercom jacks was the hardest part of the job.
    Mike Rice
    Aerolearn
    Online Aircraft Maintenance Courses
    BC12D N95910 Tale Dragon
    TF #855

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    • #3
      Re: FL-760 Radio

      What is that thing that looks like a shunt resistor?
      Darryl

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      • #4
        Re: FL-760 Radio

        Darryl,
        It is a calibrated shunt. The meter is both a volt meter and an ammeter. By routing all ground current back through the shunt, the meter can pick off total amps across the shunt.

        BTW. I fully agree with Mike. It would be better to re-locate the headphone jacks to the side of the box and cut it down to 10 inches height.
        Last edited by Mark Julicher; 05-31-2012, 05:02.
        Best Regards,
        Mark Julicher

        Comment


        • #5
          Re: FL-760 Radio

          Thanks, Just curious; That is what it looked like, but I didn't see any voltage pick-off connections (probably on hidden side), so I wasn't sure. Big mamoo though.
          DC

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