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Radio help

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  • fishmaster232
    This is for all you electronic gurus out there. I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked earlier this summer,
    Message 1 of 20 , Sep 5, 2010
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      This is for all you electronic gurus out there.

      I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked earlier this summer, transmitted to my base handheld @ about 5 miles.

      The radio now only transmits several hundred yards now. receives very well.

      The stuff I've done since it worked was dashboard off about 5 times installing analog gages, and hard wired my GPS. no other power items added but the GPS.

      While checking the wiring for the radio I found the center post wire at the antenna was loose.

      Could this have blown something in the radio?

      Things I've tried: tightened antenna, bought new battery, wired direct to new battery, then to my truck battery while running (14 volts)

      I am planning on taking the radio out and sending it for repair, but want to know if I missed checking something first.



      Thanks,

      Rod
    • mckenney.eric
      I know that this isn t going to help you one bit, but we stopped by the avionics shop with my instructor(hey free flight time is fre flight time) and was
      Message 2 of 20 , Sep 5, 2010
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        I know that this isn't going to help you one bit, but we stopped by the avionics shop with my instructor(hey free flight time is fre flight time) and was looking at the same unit thinking it would be a nice size to pt in my Avid, He jst shook his head and said you don't want it.

        --- In FLY-UL@yahoogroups.com, "fishmaster232" <fishmaster232@...> wrote:
        >
        > This is for all you electronic gurus out there.
        >
        > I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked earlier this summer, transmitted to my base handheld @ about 5 miles.
        >
        > The radio now only transmits several hundred yards now. receives very well.
        >
        > The stuff I've done since it worked was dashboard off about 5 times installing analog gages, and hard wired my GPS. no other power items added but the GPS.
        >
        > While checking the wiring for the radio I found the center post wire at the antenna was loose.
        >
        > Could this have blown something in the radio?
        >
        > Things I've tried: tightened antenna, bought new battery, wired direct to new battery, then to my truck battery while running (14 volts)
        >
        > I am planning on taking the radio out and sending it for repair, but want to know if I missed checking something first.
        >
        >
        >
        > Thanks,
        >
        > Rod
        >
      • ROGER MILLS
        You probably have an impedance mis-match. A mis-match causes the RF power to bounce back instead of going out the antenna. A loose center connection might
        Message 3 of 20 , Sep 5, 2010
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          You probably have an impedance mis-match.  A mis-match causes the RF power to bounce back instead of going out the antenna.  A loose center connection might have improved the "match", when you tightened it the mis-match got worse.
           
          Shorted antenna coax will often damage the radio but usually not a mis-match.
           
          Common problems are;
           
          Use of 75 ohm automotive FM antenna--should be 50 ohm VHF antenna (shorter)=impedance mis-match,
          Use of 75 ohm (RG59) TV/video coax--should be 50 ohm rf coax (RG58) =impedance mis-match,
          Use of 75 ohm (F, RCA or UHF) connectors for TV, FM or CB--should be 50 ohm (BNC, TNC or N)=impedance mis-match,
          (Note, BNC and N connectors come in both 75 and 50 ohm versions)
          Bad shield or center connection to coax connectors or antenna base,
          Bad ground at antenna mounting bracket,
           
          If you can't find the problem, get the aircraft to some place with an avionics shop, they can check it all at the same time.  They can also provide guidance and the right coax, connectors and antenna if you want to fix it yourself.
           

          To: FLY-UL@yahoogroups.com
          From: fishmaster232@...
          Date: Sun, 5 Sep 2010 12:20:57 +0000
          Subject: UL: Radio help

           
          This is for all you electronic gurus out there.

          I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked earlier this summer, transmitted to my base handheld @ about 5 miles.

          The radio now only transmits several hundred yards now. receives very well.

          The stuff I've done since it worked was dashboard off about 5 times installing analog gages, and hard wired my GPS. no other power items added but the GPS.

          While checking the wiring for the radio I found the center post wire at the antenna was loose.

          Could this have blown something in the radio?

          Things I've tried: tightened antenna, bought new battery, wired direct to new battery, then to my truck battery while running (14 volts)

          I am planning on taking the radio out and sending it for repair, but want to know if I missed checking something first.

          Thanks,

          Rod


        • Richard Williams
          fishmaster, a loose antenna wire will result in an incorrect impedance match between the antenna and the radio. This results in a large portion of the transmit
          Message 4 of 20 , Sep 5, 2010
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            fishmaster,

            a loose antenna wire will result in an incorrect impedance match between the antenna
            and the radio.
            This results in a large portion of the transmit power being reflected back into the
            output stages (usually transistors) of the radio. All that reflected power quickly
            destroys the output transistors.

            I would be sending the radio in for repair.
            But first, you might try using a inline SWR meter, made for the aviation frequencies,
            to check the output wattage and the amount of reflected power.

            R. Williams



            ---------- Original Message -----------
            From: "fishmaster232" <fishmaster232@...>
            To: FLY-UL@yahoogroups.com
            Sent: Sun, 05 Sep 2010 12:20:57 -0000
            Subject: UL: Radio help

            > This is for all you electronic gurus out there.
            >
            > I have a Micro-Air M760 transceiver, was on the plane when I bought
            > it. It worked earlier this summer, transmitted to my base handheld @
            > about 5 miles.
            >
            > The radio now only transmits several hundred yards now. receives very well.
            >
            > The stuff I've done since it worked was dashboard off about 5 times
            > installing analog gages, and hard wired my GPS. no other power items
            > added but the GPS.
            >
            > While checking the wiring for the radio I found the center post wire
            > at the antenna was loose.
            >
            > Could this have blown something in the radio?
            >
            > Things I've tried: tightened antenna, bought new battery, wired direct
            > to new battery, then to my truck battery while running (14 volts)
            >
            > I am planning on taking the radio out and sending it for repair, but
            > want to know if I missed checking something first.
            >
            > Thanks,
            >
            > Rod
            ------- End of Original Message -------
          • Ricardo Trujillo
            Rod, If you transmitted with the antenna disconnected (or with a faulty connection) there is a chance you blew the final amplifier in your radio. Most modern
            Message 5 of 20 , Sep 5, 2010
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              Rod,
              If you transmitted with the antenna disconnected (or with a faulty connection) there is a chance you blew the final amplifier in your radio.
              Most modern transceivers have a protection circuit that will reduce the output of the radio if the Standing Wave Ratio (SWR) is too high, protecting the final transistor/module from failure.
              If you can find somebody that owns an RF power meter that is suitable for VHF, you can check your radio for power output.
              Good luck,
              Ricardo
               
              ----- Original Message -----
              Sent: Sunday, September 05, 2010 8:20 AM
              Subject: UL: Radio help

               

              This is for all you electronic gurus out there.

              I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked earlier this summer, transmitted to my base handheld @ about 5 miles.

              The radio now only transmits several hundred yards now. receives very well.

              The stuff I've done since it worked was dashboard off about 5 times installing analog gages, and hard wired my GPS. no other power items added but the GPS.

              While checking the wiring for the radio I found the center post wire at the antenna was loose.

              Could this have blown something in the radio?

              Things I've tried: tightened antenna, bought new battery, wired direct to new battery, then to my truck battery while running (14 volts)

              I am planning on taking the radio out and sending it for repair, but want to know if I missed checking something first.

              Thanks,

              Rod

            • fishmaster232
              Thanks Roger, The antenna wire that is on the unit came with the unit s installation kit. (it was shortened to about 18 tho... It says RG58 on it but I can t
              Message 6 of 20 , Sep 5, 2010
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                Thanks Roger,

                The antenna wire that is on the unit came with the unit's installation kit. (it was shortened to about 18" tho... It says RG58 on it but I can't tell the ohm of the BNC connector.

                AS far as the mis-match, the radio worked well at first, then stopped that's when I found the loose wire. If it was a mis-match I would think it would have not been working well to begin with.

                As far as the shop goes, they are very limited around here and I was trying to solve this with a eye toward finances...


                Rod



                --- In FLY-UL@yahoogroups.com, ROGER MILLS <irsmiley@...> wrote:
                >
                >
                > You probably have an impedance mis-match. A mis-match causes the RF power to bounce back instead of going out the antenna. A loose center connection might have improved the "match", when you tightened it the mis-match got worse.
                >
                > Shorted antenna coax will often damage the radio but usually not a mis-match.
                >
                > Common problems are;
                >
                > Use of 75 ohm automotive FM antenna--should be 50 ohm VHF antenna (shorter)=impedance mis-match,
                > Use of 75 ohm (RG59) TV/video coax--should be 50 ohm rf coax (RG58) =impedance mis-match,
                > Use of 75 ohm (F, RCA or UHF) connectors for TV, FM or CB--should be 50 ohm (BNC, TNC or N)=impedance mis-match,
                > (Note, BNC and N connectors come in both 75 and 50 ohm versions)
                > Bad shield or center connection to coax connectors or antenna base,
                > Bad ground at antenna mounting bracket,
                >
                > If you can't find the problem, get the aircraft to some place with an avionics shop, they can check it all at the same time. They can also provide guidance and the right coax, connectors and antenna if you want to fix it yourself.
                >
                >
                >
                > To: FLY-UL@yahoogroups.com
                > From: fishmaster232@...
                > Date: Sun, 5 Sep 2010 12:20:57 +0000
                > Subject: UL: Radio help
                >
                >
                >
                >
                >
                >
                > This is for all you electronic gurus out there.
                >
                > I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked earlier this summer, transmitted to my base handheld @ about 5 miles.
                >
                > The radio now only transmits several hundred yards now. receives very well.
                >
                > The stuff I've done since it worked was dashboard off about 5 times installing analog gages, and hard wired my GPS. no other power items added but the GPS.
                >
                > While checking the wiring for the radio I found the center post wire at the antenna was loose.
                >
                > Could this have blown something in the radio?
                >
                > Things I've tried: tightened antenna, bought new battery, wired direct to new battery, then to my truck battery while running (14 volts)
                >
                > I am planning on taking the radio out and sending it for repair, but want to know if I missed checking something first.
                >
                > Thanks,
                >
                > Rod
                >
              • fishmaster232
                Rich and Ricardo, That is what I think may have happened. I don t have the proper SWR meter so I ll just send it for repair. The repair place says it s a
                Message 7 of 20 , Sep 5, 2010
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                  Rich and Ricardo,

                  That is what I think may have happened.

                  I don't have the proper SWR meter so I'll just send it for repair.

                  The repair place says it's a minimum of $90 just to diagnose the problem, I hope it's not much more for a fix.


                  Thanks guys !!!

                  Rod



                  --- In FLY-UL@yahoogroups.com, "Richard Williams" <rkwill@...> wrote:
                  >
                  > fishmaster,
                  >
                  > a loose antenna wire will result in an incorrect impedance match between the antenna
                  > and the radio.
                  > This results in a large portion of the transmit power being reflected back into the
                  > output stages (usually transistors) of the radio. All that reflected power quickly
                  > destroys the output transistors.
                  >
                  > I would be sending the radio in for repair.
                  > But first, you might try using a inline SWR meter, made for the aviation frequencies,
                  > to check the output wattage and the amount of reflected power.
                  >
                  > R. Williams
                • fishmaster232
                  Thanks Eric, just what I needed to hear !!! It seems like a ok unit when it worked, but I was surprised it only 5 watts. Are they all that low power? Rod
                  Message 8 of 20 , Sep 5, 2010
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                    Thanks Eric, just what I needed to hear !!!

                    It seems like a ok unit when it worked, but I was surprised it only 5 watts. Are they all that low power?


                    Rod




                    --- In FLY-UL@yahoogroups.com, "mckenney.eric" <themckenneys@...> wrote:
                    >
                    > I know that this isn't going to help you one bit, but we stopped by the avionics shop with my instructor(hey free flight time is fre flight time) and was looking at the same unit thinking it would be a nice size to pt in my Avid, He jst shook his head and said you don't want it.
                  • ROGER MILLS
                    If it was a factory install kit then it probably has the right stuff. Probable that the bad connection failed the radio. Make sure that the BNC is solidly
                    Message 9 of 20 , Sep 5, 2010
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                      If it was a "factory" install kit then it probably has the right stuff.  Probable that the bad connection failed the radio.  Make sure that the BNC is solidly secure to the cable--it should not twist.
                       

                      To: FLY-UL@yahoogroups.com
                      From: fishmaster232@...
                      Date: Sun, 5 Sep 2010 20:46:35 +0000
                      Subject: Re: UL: Radio help

                       
                      Thanks Roger,

                      The antenna wire that is on the unit came with the unit's installation kit. (it was shortened to about 18" tho... It says RG58 on it but I can't tell the ohm of the BNC connector.

                      AS far as the mis-match, the radio worked well at first, then stopped that's when I found the loose wire. If it was a mis-match I would think it would have not been working well to begin with.

                      As far as the shop goes, they are very limited around here and I was trying to solve this with a eye toward finances...

                      Rod

                      --- In FLY-UL@yahoogroups.com, ROGER MILLS <irsmiley@...> wrote:
                      >
                      >
                      > You probably have an impedance mis-match. A mis-match causes the RF power to bounce back instead of going out the antenna. A loose center connection might have improved the "match", when you tightened it the mis-match got worse.
                      >
                      > Shorted antenna coax will often damage the radio but usually not a mis-match.
                      >
                      > Common problems are;
                      >
                      > Use of 75 ohm automotive FM antenna--should be 50 ohm VHF antenna (shorter)=impedance mis-match,
                      > Use of 75 ohm (RG59) TV/video coax--should be 50 ohm rf coax (RG58) =impedance mis-match,
                      > Use of 75 ohm (F, RCA or UHF) connectors for TV, FM or CB--should be 50 ohm (BNC, TNC or N)=impedance mis-match,
                      > (Note, BNC and N connectors come in both 75 and 50 ohm versions)
                      > Bad shield or center connection to coax connectors or antenna base,
                      > Bad ground at antenna mounting bracket,
                      >
                      > If you can't find the problem, get the aircraft to some place with an avionics shop, they can check it all at the same time. They can also provide guidance and the right coax, connectors and antenna if you want to fix it yourself.
                      >
                      >
                      >
                      > To: FLY-UL@yahoogroups.com
                      > From: fishmaster232@...
                      > Date: Sun, 5 Sep 2010 12:20:57 +0000
                      > Subject: UL: Radio help
                      >
                      >
                      >
                      >
                      >
                      >
                      > This is for all you electronic gurus out there.
                      >
                      > I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked earlier this summer, transmitted to my base handheld @ about 5 miles.
                      >
                      > The radio now only transmits several hundred yards now. receives very well.
                      >
                      > The stuff I've done since it worked was dashboard off about 5 times installing analog gages, and hard wired my GPS. no other power items added but the GPS.
                      >
                      > While checking the wiring for the radio I found the center post wire at the antenna was loose.
                      >
                      > Could this have blown something in the radio?
                      >
                      > Things I've tried: tightened antenna, bought new battery, wired direct to new battery, then to my truck battery while running (14 volts)
                      >
                      > I am planning on taking the radio out and sending it for repair, but want to know if I missed checking something first.
                      >
                      > Thanks,
                      >
                      > Rod
                      >


                    • mckenney.eric
                      It has about the same power as a handheld
                      Message 10 of 20 , Sep 5, 2010
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                        It has about the same power as a handheld

                        --- In FLY-UL@yahoogroups.com, "fishmaster232" <fishmaster232@...> wrote:
                        >
                        > Thanks Eric, just what I needed to hear !!!
                        >
                        > It seems like a ok unit when it worked, but I was surprised it only 5 watts. Are they all that low power?
                        >
                        >
                        > Rod
                        >
                        >
                        >
                        >
                        > --- In FLY-UL@yahoogroups.com, "mckenney.eric" <themckenneys@> wrote:
                        > >
                        > > I know that this isn't going to help you one bit, but we stopped by the avionics shop with my instructor(hey free flight time is fre flight time) and was looking at the same unit thinking it would be a nice size to pt in my Avid, He jst shook his head and said you don't want it.
                        >
                      • Bill
                        RG58 is 50 ohm cable - the BNC connector does not have a specific impedance to worry about in this application, mostly deals with if it will fit on the cable.
                        Message 11 of 20 , Sep 5, 2010
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                          RG58 is 50 ohm cable - the BNC connector does not have a specific impedance to worry
                          about in this application, mostly deals with if it will fit on the cable. If the cable
                          was RG59, then it'd be 75ohm impedance. Remember that this is not something that can
                          be measured with an ohm meter, it only has this resistance with radio frequencies.
                          Your ohm meter will hopefully show a dead short. RG-58C/U cable is optimum for
                          aviation radio frequencies without getting over priced.

                          If you go to your local EAA meeting, someone there will likely be able to help match
                          your radio to your antenna.

                          Test your radio with an rubber ducky antenna to quickly see if you've blown anything.

                          Bill Watson
                          bill@...

                          ---------- Original Message -----------
                          From: ROGER MILLS <irsmiley@...>
                          To: <fly-ul@yahoogroups.com>
                          Sent: Sun, 5 Sep 2010 17:17:14 -0600
                          Subject: RE: UL: Radio help

                          > If it was a "factory" install kit then it probably has the right stuff.
                          > Probable that the bad connection failed the radio. Make sure that the BNC is
                          > solidly secure to the cable--it should not twist.
                          >
                          > To: FLY-UL@yahoogroups.com
                          > From: fishmaster232@...
                          > Date: Sun, 5 Sep 2010 20:46:35 +0000
                          > Subject: Re: UL: Radio help
                          >
                          > Thanks Roger,
                          >
                          > The antenna wire that is on the unit came with the unit's installation kit.
                          > (it was shortened to about 18" tho... It says RG58 on it but I can't tell the
                          > ohm of the BNC connector.
                          >
                          > AS far as the mis-match, the radio worked well at first, then stopped that's
                          > when I found the loose wire. If it was a mis-match I would think it would have
                          > not been working well to begin with.
                          >
                          > As far as the shop goes, they are very limited around here and I was trying to
                          > solve this with a eye toward finances...
                          >
                          > Rod
                          >
                          > --- In FLY-UL@yahoogroups.com, ROGER MILLS <irsmiley@...> wrote:
                          > >
                          > >
                          > > You probably have an impedance mis-match. A mis-match causes the RF power to
                          bounce back instead of going out the antenna. A loose center connection might have
                          improved the "match", when you tightened it the mis-match got worse.
                          > >
                          > > Shorted antenna coax will often damage the radio but usually not a mis-match.
                          > >
                          > > Common problems are;
                          > >
                          > > Use of 75 ohm automotive FM antenna--should be 50 ohm VHF antenna (shorter)
                          =impedance mis-match,
                          > > Use of 75 ohm (RG59) TV/video coax--should be 50 ohm rf coax (RG58) =impedance mis-
                          match,
                          > > Use of 75 ohm (F, RCA or UHF) connectors for TV, FM or CB--should be 50 ohm (BNC,
                          TNC or N)=impedance mis-match,
                          > > (Note, BNC and N connectors come in both 75 and 50 ohm versions)
                          > > Bad shield or center connection to coax connectors or antenna base,
                          > > Bad ground at antenna mounting bracket,
                          > >
                          > > If you can't find the problem, get the aircraft to some place with an avionics
                          shop, they can check it all at the same time. They can also provide guidance and the
                          right coax, connectors and antenna if you want to fix it yourself.
                          > >
                          > >
                          > >
                          > > To: FLY-UL@yahoogroups.com
                          > > From: fishmaster232@...
                          > > Date: Sun, 5 Sep 2010 12:20:57 +0000
                          > > Subject: UL: Radio help
                          > >
                          > >
                          > >
                          > >
                          > >
                          > >
                          > > This is for all you electronic gurus out there.
                          > >
                          > > I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked
                          earlier this summer, transmitted to my base handheld @ about 5 miles.
                          > >
                          > > The radio now only transmits several hundred yards now. receives very well.
                          > >
                          > > The stuff I've done since it worked was dashboard off about 5 times installing
                          analog gages, and hard wired my GPS. no other power items added but the GPS.
                          > >
                          > > While checking the wiring for the radio I found the center post wire at the
                          antenna was loose.
                          > >
                          > > Could this have blown something in the radio?
                          > >
                          > > Things I've tried: tightened antenna, bought new battery, wired direct to new
                          battery, then to my truck battery while running (14 volts)
                          > >
                          > > I am planning on taking the radio out and sending it for repair, but want to know
                          if I missed checking something first.
                          > >
                          > > Thanks,
                          > >
                          > > Rod
                          > >
                          ------- End of Original Message -------
                        • fishmaster232
                          HI Bill, I think my radio and antenna are matched, as I said before it worked fine before I started screwing around under the dash. I may have loosened the
                          Message 12 of 20 , Sep 6, 2010
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                            HI Bill,

                            I think my radio and antenna are matched, as I said before it worked fine before I started screwing around under the dash. I may have loosened the antenna wire then, but I don't think I could have unmatched them.

                            I don't know what type of antenna it is, but I just saw 3 planes at a local fly-in with the same antenna, but different radios.

                            In the radio manual it warns against using a rubber-ducky portable radio antenna for some unexplained reason.


                            Rod




                            --- In FLY-UL@yahoogroups.com, "Bill" <bill@...> wrote:
                            >
                            > RG58 is 50 ohm cable - the BNC connector does not have a specific impedance to worry
                            > about in this application, mostly deals with if it will fit on the cable. If the cable
                            > was RG59, then it'd be 75ohm impedance. Remember that this is not something that can
                            > be measured with an ohm meter, it only has this resistance with radio frequencies.
                            > Your ohm meter will hopefully show a dead short. RG-58C/U cable is optimum for
                            > aviation radio frequencies without getting over priced.
                            >
                            > If you go to your local EAA meeting, someone there will likely be able to help match
                            > your radio to your antenna.
                            >
                            > Test your radio with an rubber ducky antenna to quickly see if you've blown anything.
                            >
                            > Bill Watson
                            > bill@...
                          • fishmaster232
                            Bill, What is the C/U in RG-58C/U ??
                            Message 13 of 20 , Sep 6, 2010
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                              Bill,

                              What is the "C/U" in RG-58C/U ??



                              > Your ohm meter will hopefully show a dead short. RG-58C/U cable is optimum for
                              > aviation radio frequencies without getting over priced.
                              > Bill Watson
                            • fishmaster232
                              You d think for $900+ it would have a bit more power.... Rod
                              Message 14 of 20 , Sep 6, 2010
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                                You'd think for $900+ it would have a bit more power....

                                Rod

                                --- In FLY-UL@yahoogroups.com, "mckenney.eric" <themckenneys@...> wrote:
                                >
                                > It has about the same power as a handheld
                                >
                                > --- In FLY-UL@yahoogroups.com, "fishmaster232" <fishmaster232@> wrote:
                                > >
                                > > Thanks Eric, just what I needed to hear !!!
                                > >
                                > > It seems like a ok unit when it worked, but I was surprised it only 5 watts. Are they all that low power?
                                > >
                                > >
                                > > Rod
                                > >
                                > >
                                > >
                                > >
                                > > --- In FLY-UL@yahoogroups.com, "mckenney.eric" <themckenneys@> wrote:
                                > > >
                                > > > I know that this isn't going to help you one bit, but we stopped by the avionics shop with my instructor(hey free flight time is fre flight time) and was looking at the same unit thinking it would be a nice size to pt in my Avid, He jst shook his head and said you don't want it.
                                > >
                                >
                              • ROGER MILLS
                                Version code for the cable, identifies type of insulation etc. CAREFUL, many whip type antenna read open not shorted. Many of the hand held antenna are
                                Message 15 of 20 , Sep 6, 2010
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                                  Version code for the cable, identifies type of insulation etc.
                                   
                                  CAREFUL, many 'whip' type antenna read open not shorted.  Many of the hand held antenna are actually a flexible coil and will read short, some radios do not like that.
                                   
                                  Disconnect the coax from the radio and antenna and then check the coax from center to outside shell of the connector--reads open, check center end to end--reads short, check shell of connector to the shield at the antenna end--reads short.  AFTER you re-connect the center and shield at the antenna use some silicone on the screws or nuts to keep them from getting loose, don't get it under the nuts or screw heads.
                                   

                                  To: FLY-UL@yahoogroups.com
                                  From: fishmaster232@...
                                  Date: Mon, 6 Sep 2010 16:07:27 +0000
                                  Subject: Re: UL: Radio help

                                   
                                  Bill,

                                  What is the "C/U" in RG-58C/U ??

                                  > Your ohm meter will hopefully show a dead short. RG-58C/U cable is optimum for
                                  > aviation radio frequencies without getting over priced.
                                  > Bill Watson


                                • mark47620
                                  ... loose wires to the antenna can blow the final amplifiers in the sending system, rcv will still work fine,,,,,,,,,, also, friend has the same radio and has
                                  Message 16 of 20 , Sep 8, 2010
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                                    --- In FLY-UL@yahoogroups.com, "mckenney.eric" <themckenneys@...> wrote:
                                    >
                                    > I know that this isn't going to help you one bit, but we stopped by the avionics shop with my instructor(hey free flight time is fre flight time) and was looking at the same unit thinking it would be a nice size to pt in my Avid, He jst shook his head and said you don't want it.

                                    loose wires to the antenna can blow the final amplifiers in the sending system, rcv will still work fine,,,,,,,,,,

                                    also, friend has the same radio and has had a myriad of problems related to being kinda small and subject to vibration

                                    sen ti in once a month for several months

                                    then swapped it out for a new one, now problems with the new one

                                    wishes he had a bigger more reliable one rather than that spensive little one,

                                    mark
                                  • fishmaster232
                                    Ok, here is a update and another question... I tested the antenna wire for shorts and found none, so I sent the radio in to be checked and and they found
                                    Message 17 of 20 , Sep 15, 2010
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                                      Ok, here is a update and another question...

                                      I tested the antenna wire for shorts and found none, so I sent the radio in to be checked and and they found nothing wrong and it air tested to 25 miles easily they said.

                                      The tech suggested the ground plane was not big enough, I have a 24" 50ohm 1/4 wave and he said that needs a 4' ground plane to work to full strength. He said I could use two 4' wires in a cross and attach the ground to the center of the cross.

                                      The question I didn't think to ask him was: I have a alum. floor plate on my CGS Hawk Arrow II. about 18" wide by 6' long. if I re-mount the antenna to the bottom of the plane, can I use the floor plate as the fore and aft section of the ground plane?

                                      What kind of wire should be used, solid? gage?

                                      thanks guys !!!

                                      Rod




                                      --- In FLY-UL@yahoogroups.com, "Bill" <bill@...> wrote:
                                      >
                                      > RG58 is 50 ohm cable - the BNC connector does not have a specific impedance to worry
                                      > about in this application, mostly deals with if it will fit on the cable. If the cable
                                      > was RG59, then it'd be 75ohm impedance. Remember that this is not something that can
                                      > be measured with an ohm meter, it only has this resistance with radio frequencies.
                                      > Your ohm meter will hopefully show a dead short. RG-58C/U cable is optimum for
                                      > aviation radio frequencies without getting over priced.
                                      >
                                      > If you go to your local EAA meeting, someone there will likely be able to help match
                                      > your radio to your antenna.
                                      >
                                      > Test your radio with an rubber ducky antenna to quickly see if you've blown anything.
                                      >
                                      > Bill Watson
                                      > bill@...
                                      >
                                      > ---------- Original Message -----------
                                      > From: ROGER MILLS <irsmiley@...>
                                      > To: <fly-ul@yahoogroups.com>
                                      > Sent: Sun, 5 Sep 2010 17:17:14 -0600
                                      > Subject: RE: UL: Radio help
                                      >
                                      > > If it was a "factory" install kit then it probably has the right stuff.
                                      > > Probable that the bad connection failed the radio. Make sure that the BNC is
                                      > > solidly secure to the cable--it should not twist.
                                      > >
                                      > > To: FLY-UL@yahoogroups.com
                                      > > From: fishmaster232@...
                                      > > Date: Sun, 5 Sep 2010 20:46:35 +0000
                                      > > Subject: Re: UL: Radio help
                                      > >
                                      > > Thanks Roger,
                                      > >
                                      > > The antenna wire that is on the unit came with the unit's installation kit.
                                      > > (it was shortened to about 18" tho... It says RG58 on it but I can't tell the
                                      > > ohm of the BNC connector.
                                      > >
                                      > > AS far as the mis-match, the radio worked well at first, then stopped that's
                                      > > when I found the loose wire. If it was a mis-match I would think it would have
                                      > > not been working well to begin with.
                                      > >
                                      > > As far as the shop goes, they are very limited around here and I was trying to
                                      > > solve this with a eye toward finances...
                                      > >
                                      > > Rod
                                      > >
                                      > > --- In FLY-UL@yahoogroups.com, ROGER MILLS <irsmiley@> wrote:
                                      > > >
                                      > > >
                                      > > > You probably have an impedance mis-match. A mis-match causes the RF power to
                                      > bounce back instead of going out the antenna. A loose center connection might have
                                      > improved the "match", when you tightened it the mis-match got worse.
                                      > > >
                                      > > > Shorted antenna coax will often damage the radio but usually not a mis-match.
                                      > > >
                                      > > > Common problems are;
                                      > > >
                                      > > > Use of 75 ohm automotive FM antenna--should be 50 ohm VHF antenna (shorter)
                                      > =impedance mis-match,
                                      > > > Use of 75 ohm (RG59) TV/video coax--should be 50 ohm rf coax (RG58) =impedance mis-
                                      > match,
                                      > > > Use of 75 ohm (F, RCA or UHF) connectors for TV, FM or CB--should be 50 ohm (BNC,
                                      > TNC or N)=impedance mis-match,
                                      > > > (Note, BNC and N connectors come in both 75 and 50 ohm versions)
                                      > > > Bad shield or center connection to coax connectors or antenna base,
                                      > > > Bad ground at antenna mounting bracket,
                                      > > >
                                      > > > If you can't find the problem, get the aircraft to some place with an avionics
                                      > shop, they can check it all at the same time. They can also provide guidance and the
                                      > right coax, connectors and antenna if you want to fix it yourself.
                                      > > >
                                      > > >
                                      > > >
                                      > > > To: FLY-UL@yahoogroups.com
                                      > > > From: fishmaster232@
                                      > > > Date: Sun, 5 Sep 2010 12:20:57 +0000
                                      > > > Subject: UL: Radio help
                                      > > >
                                      > > >
                                      > > >
                                      > > >
                                      > > >
                                      > > >
                                      > > > This is for all you electronic gurus out there.
                                      > > >
                                      > > > I have a Micro-Air M760 transceiver, was on the plane when I bought it. It worked
                                      > earlier this summer, transmitted to my base handheld @ about 5 miles.
                                      > > >
                                      > > > The radio now only transmits several hundred yards now. receives very well.
                                      > > >
                                      > > > The stuff I've done since it worked was dashboard off about 5 times installing
                                      > analog gages, and hard wired my GPS. no other power items added but the GPS.
                                      > > >
                                      > > > While checking the wiring for the radio I found the center post wire at the
                                      > antenna was loose.
                                      > > >
                                      > > > Could this have blown something in the radio?
                                      > > >
                                      > > > Things I've tried: tightened antenna, bought new battery, wired direct to new
                                      > battery, then to my truck battery while running (14 volts)
                                      > > >
                                      > > > I am planning on taking the radio out and sending it for repair, but want to know
                                      > if I missed checking something first.
                                      > > >
                                      > > > Thanks,
                                      > > >
                                      > > > Rod
                                      > > >
                                      > ------- End of Original Message -------
                                      >
                                    • Jim M
                                      I would first try mounting the antenna to the aluminum floor and see if that works. If that does not work I would than attach the wire to the aluminum floor
                                      Message 18 of 20 , Sep 17, 2010
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                                        I would first try mounting the antenna to the aluminum floor and see if that works. If that does not work I would than attach the wire to the aluminum floor plate. I fly an aircraft with an antenna mounted to an aluminum plate of about 3.5ft x 2ft that is under the pilot's seat. The plate is grounded to the metal tubing of the aircraft structure and the antenna is pointed downward towards the ground. The system works just fine with my handheld ICOM radio.
                                      • fishmaster232
                                        Thanks Jim, I saw two Hawks at a recent fly-in with the same hook-up you described and the same antenna I have. I will try that. Thanks again, Rod
                                        Message 19 of 20 , Sep 17, 2010
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                                          Thanks Jim,

                                          I saw two Hawks at a recent fly-in with the same hook-up you described and the same antenna I have. I will try that.


                                          Thanks again,

                                          Rod



                                          --- In FLY-UL@yahoogroups.com, "Jim M" <jbmm211@...> wrote:
                                          >
                                          > I would first try mounting the antenna to the aluminum floor and see if that works. If that does not work I would than attach the wire to the aluminum floor plate. I fly an aircraft with an antenna mounted to an aluminum plate of about 3.5ft x 2ft that is under the pilot's seat. The plate is grounded to the metal tubing of the aircraft structure and the antenna is pointed downward towards the ground. The system works just fine with my handheld ICOM radio.
                                          >
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