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Re: [FT897] NEW HAM - FT-897 to FT-2900 Simplex Transmit/Receive Range

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  • Matt
    Hi Donovan, the answer is that it depends on a number of issues. Firstly, is the base antenna mounted outside or sitting inside your house - and what height
    Message 1 of 10 , Apr 1, 2013
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      Hi Donovan, the answer is that it depends on a number of issues. Firstly, is
      the base antenna mounted outside or sitting inside your house - and what
      height above ground level is it? What is the terrain like over the distance
      that you are trying to communicate over and is your house elevated or in a
      valley? Have you tested the antenna and feedline in both the car and the
      house to see if they are resonant or near resonant for the frequency in use.
      Do you have a long coax run between the radio and the antenna at the house -
      what length is it and what type of cable?

      If in flat terrain and the antennas are in good working order, then I would
      expect way more than 5 miles range. But, lots of variables to look at.


      Matt
      VK1MA

      ----- Original Message -----
      From: "dcawood" <dcawood@...>
      To: <FT897@yahoogroups.com>
      Sent: Monday, April 01, 2013 2:57 AM
      Subject: [FT897] NEW HAM - FT-897 to FT-2900 Simplex Transmit/Receive Range


      > Hello,
      >
      > I just installed a FT-2900 VHF Transceiver in my wife's car. The radio is
      > transmitting at 75watts and is connected to a 19.5 inch mag mount 2m/70cm
      > antenna. I had to go with that antenna because her antenna is already
      > hitting the top of the garage entrance. The base station is a FT-897D
      > connected to a 2m/70cm Ventenna operating at 50watts.
      >
      > Today we did our first drive test. She started from downtown Dallas and I
      > was at home in west Plano.
      >
      > My first contact to her was when she got to northwest highway which is
      > about 15 miles out. With my rx gain at its highest level, I was not able
      > to receive her till she reached Frankford which is about 5 miles out. With
      > the FT-2900 set to 75watt, even on a 19.5" magmount antenna, shouldn't I
      > be able to hear her at least 15 miles out rather then 5 miles out?
      >
      > Regards,
      > Donovan - KF5TSH
      >
      >
      >
      > ------------------------------------
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
    • Charles Scott
      Dennis: Coiling coax will only choke off what s called common-mode currents. That s the RF that rides on the outside of the coax and is generally what you
      Message 2 of 10 , Apr 1, 2013
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        Dennis:

        Coiling coax will only choke off what's called "common-mode" currents.
        That's the RF that rides on the outside of the coax and is generally
        what you don't want. Coiling coax does not affect current inside the
        cable unless the coax is coiled so tight that it actually damages the
        insulation or substantially changes the distance between the center
        conductor and the inside of the shield. If the coax is not damaged, RF
        will flow through it just fine, coiled or not.

        In a mobile installation, you want RF outside the vehicle. Depending on
        the installation, it's possible that RF will be coupled onto the outside
        of the shield of the coax cable, particularly if it runs outside the car
        to the antenna. When this happens, it can be conducted into the car
        where the coax comes in. That's not good because it results in stray RF
        in the vehicle and permits noise coupled into the transmission line from
        things inside the vehicle to get back out to the antenna. Coiling the
        coax cable right where it enters the vehicle will help to choke off that
        RF on the outside of the cable. This can also be done with clamp-on or
        toroid cores on the cable. I always choke common-mode currents where any
        cables enter my vehicle.

        As to this person's experience with distance, I agree that it depends on
        so many things including but not limited to installation at both ends,
        antenna placement and tuning, position of the antenna with regard to
        surrounding terrain and obstructions, band being used, tropospheric
        propagation conditions, multi-path, etc, that it's really hard to say
        whether 5 miles or 15 Miles is good or not. From experience, I'd have to
        say that with good mobile antennas talking to a decent fixed station and
        reasonable power, 5 miles should certainly be expected in reasonably
        flat and clear terrain. 15 miles would be reasonable if the base antenna
        is reasonably up in the clear. More than that depends a lot on the
        antennas, terrain, and propagation.

        If the base antenna is a good high-gain antenna well up in the clear
        (which he doesn't have) and the mobile is using a good antenna up on the
        top of the car (we don't really know), or something like a mobile
        colinear up in the clear, on 2 Meters (he didn't say) and there's good
        terrain, much more than 15 miles can be expected most of the time.
        That's apparently not the situation in his case.

        So, my answer to the original question about 15 miles is, yes, sort of,
        depending, and possibly.

        Chuck - N8DNX



        On 3/31/2013 10:27 PM, Dennis wrote:
        > This would depend on a multitude of things. First, how much coax
        > is/was/may have been left over in the mobile and did you wind/coil it
        > up? If you did, you just created a choke on the antenna and would have
        > severely limited TX. Uncoil it and run it without coiling/crossing it.
        >
      • Joel
        I have both those rigs and you dont seem to be getting a reasonable distance if your rigs and antennas are in good order. I think that your terrain is pretty
        Message 3 of 10 , Apr 1, 2013
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          I have both those rigs and you dont seem to be getting a reasonable
          distance if your
          rigs and antennas are in good order. I think that your terrain is
          pretty flat if I remember
          correctly.

          I have a 5W HT in my pickup with a 19 inch whip mag mount on the cab and
          I regularly talk
          10 miles mobile to mobile.here. I regularly talk with my HT to a fixed
          station 5 miles or more solid copy. I would
          check the antennas and make sure they are in good order.

          I have to say that a 5/8 Wave 2M mobile antenna clamped to a rain gutter
          may be better than that
          ventenna. I have good success with a 1/4 ground plane in my attic as my
          monitor / local contact antenna.

          But, as someone else said - thats the reason 2M repeaters became so
          popular.



          On 3/31/2013 10:57 AM, dcawood wrote:
          >
          > Hello,
          >
          > I just installed a FT-2900 VHF Transceiver in my wife's car. The radio
          > is transmitting at 75watts and is connected to a 19.5 inch mag mount
          > 2m/70cm antenna. I had to go with that antenna because her antenna is
          > already hitting the top of the garage entrance. The base station is a
          > FT-897D connected to a 2m/70cm Ventenna operating at 50watts.
          >
          > Today we did our first drive test. She started from downtown Dallas
          > and I was at home in west Plano.
          >
          > My first contact to her was when she got to northwest highway which is
          > about 15 miles out. With my rx gain at its highest level, I was not
          > able to receive her till she reached Frankford which is about 5 miles
          > out. With the FT-2900 set to 75watt, even on a 19.5" magmount antenna,
          > shouldn't I be able to hear her at least 15 miles out rather then 5
          > miles out?
          >
          > Regards,
          > Donovan - KF5TSH
          >
          >
          >
          > No virus found in this message.
          > Checked by AVG - www.avg.com <http://www.avg.com>
          > Version: 2012.0.2240 / Virus Database: 2641/5717 - Release Date: 03/31/13
          >

          --
          KQØJ



          [Non-text portions of this message have been removed]
        • Dennis
          The coax being coiled does make a difference. I have seen it in person and the wow factor after it was straightened out. In this case, if memory serves, he
          Message 4 of 10 , Apr 1, 2013
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            The coax being coiled does make a difference. I have seen it in person
            and the "wow" factor after it was straightened out. In this case, if
            memory serves, he is on the side of a "mountain" (based on different
            post about different subject).

            But in agreement, there are so many factors in UHf/VHf that it can make
            someone say "why bother?". However, the mobile is pushing 75 watts. He
            SHOULD have heard SOMETHING at 15 miles, even a small S-1 something but
            again, it could be the local noise level killed that too. We just don't
            know. We are working on this off board at this time. I gave him
            several things to check on and am waiting the outcome of that
            investigation before moving on tho something else.

            Dennis - N8BMB
            On 4/1/2013 09:34, Charles Scott wrote:
            >
            > Dennis:
            >
            > Coiling coax will only choke off what's called "common-mode" currents.
            > That's the RF that rides on the outside of the coax and is generally
            > what you don't want. Coiling coax does not affect current inside the
            > cable unless the coax is coiled so tight that it actually damages the
            > insulation or substantially changes the distance between the center
            > conductor and the inside of the shield. If the coax is not damaged, RF
            > will flow through it just fine, coiled or not.
            >
            > In a mobile installation, you want RF outside the vehicle. Depending on
            > the installation, it's possible that RF will be coupled onto the outside
            > of the shield of the coax cable, particularly if it runs outside the car
            > to the antenna. When this happens, it can be conducted into the car
            > where the coax comes in. That's not good because it results in stray RF
            > in the vehicle and permits noise coupled into the transmission line from
            > things inside the vehicle to get back out to the antenna. Coiling the
            > coax cable right where it enters the vehicle will help to choke off that
            > RF on the outside of the cable. This can also be done with clamp-on or
            > toroid cores on the cable. I always choke common-mode currents where any
            > cables enter my vehicle.
            >
            > As to this person's experience with distance, I agree that it depends on
            > so many things including but not limited to installation at both ends,
            > antenna placement and tuning, position of the antenna with regard to
            > surrounding terrain and obstructions, band being used, tropospheric
            > propagation conditions, multi-path, etc, that it's really hard to say
            > whether 5 miles or 15 Miles is good or not. From experience, I'd have to
            > say that with good mobile antennas talking to a decent fixed station and
            > reasonable power, 5 miles should certainly be expected in reasonably
            > flat and clear terrain. 15 miles would be reasonable if the base antenna
            > is reasonably up in the clear. More than that depends a lot on the
            > antennas, terrain, and propagation.
            >
            > If the base antenna is a good high-gain antenna well up in the clear
            > (which he doesn't have) and the mobile is using a good antenna up on the
            > top of the car (we don't really know), or something like a mobile
            > colinear up in the clear, on 2 Meters (he didn't say) and there's good
            > terrain, much more than 15 miles can be expected most of the time.
            > That's apparently not the situation in his case.
            >
            > So, my answer to the original question about 15 miles is, yes, sort of,
            > depending, and possibly.
            >
            > Chuck - N8DNX
            >
            > On 3/31/2013 10:27 PM, Dennis wrote:
            > > This would depend on a multitude of things. First, how much coax
            > > is/was/may have been left over in the mobile and did you wind/coil it
            > > up? If you did, you just created a choke on the antenna and would have
            > > severely limited TX. Uncoil it and run it without coiling/crossing it.
            > >
            >
            >



            [Non-text portions of this message have been removed]
          • Radio_Randy
            I, too, must disagree with the inference that coiled coax causes a noticeable loss in range. If this were the case, coax baluns would have been rejected, years
            Message 5 of 10 , Apr 1, 2013
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              I, too, must disagree with the inference that coiled coax causes a noticeable loss in range. If this were the case, coax baluns would have been rejected, years ago.

              I operate a VHF communications over a large part of rural Washington state and have never noticed any coverage differences in mobiles with coax either coiled or not. Of course, if your friend's coax was of the foam variety, I would have attributed the improvement to the center conductor migrating to the shield braid, which I have seen.

              73, Radio Randy N7CKJ

              --- In FT897@yahoogroups.com, Dennis <n8bmb1@...> wrote:
              >
              > The coax being coiled does make a difference. I have seen it in person
              > and the "wow" factor after it was straightened out. In this case, if
              > memory serves, he is on the side of a "mountain" (based on different
              > post about different subject).
              >
              > But in agreement, there are so many factors in UHf/VHf that it can make
              > someone say "why bother?". However, the mobile is pushing 75 watts. He
              > SHOULD have heard SOMETHING at 15 miles, even a small S-1 something but
              > again, it could be the local noise level killed that too. We just don't
              > know. We are working on this off board at this time. I gave him
              > several things to check on and am waiting the outcome of that
              > investigation before moving on tho something else.
              >
              > Dennis - N8BMB
            • Alex
              Hi Donovan; The answer is: Yes, you should be able to communicate for a lot more than five miles . Get a SWR meter either off ebay or amazon and check your
              Message 6 of 10 , Apr 22, 2013
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                Hi Donovan;
                The answer is: "Yes, you should be able to communicate for a lot more than five miles". Get a SWR meter either off ebay or amazon and check your antennas. The feed line does not need to be resonant if it is 50 ohm coax, but the antennas definitely need to be resonant, that is, SWR of 2:1 or less. If the antennas are cut for 450, and they are both vertically polarized, you should get "line of sight" all day long, which is a bit more than 5 miles even in flat terrain IF (very large "if")your base antenna is off the ground level. Of course, if your base antenna is only a few feet, then 5 miles might be all you can do. See: http://en.wikipedia.org/wiki/Line-of-sight_propagation
                I would play around with it (the HAM way!), and see what I got with different installations and configurations.

                Note: If your home/base ant. is horizontal and the mobile is vertical (almost certain), then you will have a LOT of attenuation, some say as much as 50dB.
                Another note: Use of a SWR meter is very important in both mobile and base operation. Antennas are rarely tuned from the factory due to the fact that the installation can change the SWR radically. A resonant stretch of coax on VHF can cause lots of problems; stay with a random stretch and tune the antenna. Ebay has several workable SWR meters for under $40 US. Make SURE you get the one for VHF/UHF.

                There's more, but all that is a start...


                No repeaters out there?

                73 es GUD DX.

                Alex KC4BO

                --- In FT897@yahoogroups.com, "Matt" <doormatt@...> wrote:
                >
                > Hi Donovan, the answer is that it depends on a number of issues. Firstly, is
                > the base antenna mounted outside or sitting inside your house - and what
                > height above ground level is it? What is the terrain like over the distance
                > that you are trying to communicate over and is your house elevated or in a
                > valley? Have you tested the antenna and feedline in both the car and the
                > house to see if they are resonant or near resonant for the frequency in use.
                > Do you have a long coax run between the radio and the antenna at the house -
                > what length is it and what type of cable?
                >
                > If in flat terrain and the antennas are in good working order, then I would
                > expect way more than 5 miles range. But, lots of variables to look at.
                >
                >
                > Matt
                > VK1MA
                >
                > ----- Original Message -----
                > From: "dcawood" <dcawood@...>
                > To: <FT897@yahoogroups.com>
                > Sent: Monday, April 01, 2013 2:57 AM
                > Subject: [FT897] NEW HAM - FT-897 to FT-2900 Simplex Transmit/Receive Range
                >
                >
                > > Hello,
                > >
                > > I just installed a FT-2900 VHF Transceiver in my wife's car. The radio is
                > > transmitting at 75watts and is connected to a 19.5 inch mag mount 2m/70cm
                > > antenna. I had to go with that antenna because her antenna is already
                > > hitting the top of the garage entrance. The base station is a FT-897D
                > > connected to a 2m/70cm Ventenna operating at 50watts.
                > >
                > > Today we did our first drive test. She started from downtown Dallas and I
                > > was at home in west Plano.
                > >
                > > My first contact to her was when she got to northwest highway which is
                > > about 15 miles out. With my rx gain at its highest level, I was not able
                > > to receive her till she reached Frankford which is about 5 miles out. With
                > > the FT-2900 set to 75watt, even on a 19.5" magmount antenna, shouldn't I
                > > be able to hear her at least 15 miles out rather then 5 miles out?
                > >
                > > Regards,
                > > Donovan - KF5TSH
                > >
                > >
                > >
                > > ------------------------------------
                > >
                > > Yahoo! Groups Links
                > >
                > >
                > >
                > >
                >
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