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Antenna Tuning Unit needed or not for mobile and portable?

Discussion in 'Mobile Radio Systems' started by M6AGL, Oct 7, 2019.

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  1. M6AGL

    M6AGL Ham Member QRZ Page

    I'm just progressing from a 2M rig to a Yaesu FT857 which is HF, 2M & 70cm. The 2M&70cm is a separate antenna out, so that would be ok to use a dual band antenna I think, but what do most of you do for HF use?

    Do you keep a collection of antennas in the back and just swap them around which I have seen some users do, or do you use a screwdriver type adjustable load antenna - which are pretty huge by UK standards?

    I think I may end up driving around with a whip tuned for 14MHz and 28MHz in the back, and some kind of push up pole end fed antenna if I'm staying somewhere longer.- But would I probably need an ATU for that?

    Do you prefer a manual type matchbox or an electronic ATU? I see the competition field day folk seem to prefer the electronic black box atu's.

    Fitting and holes not a problem - it's a Landrover, but being an alloy roof I'll use the military side antenna mount.
  2. K0BG

    K0BG Ham Member QRZ Page

  3. M6AGL

    M6AGL Ham Member QRZ Page

    Thank you for the effort you have put into that. May take me a few days to read it and probably a lot longer to fully understand the concepts, but I do appreciate the knowledge.
    Thank you for sharing it.
    AJ5J likes this.
  4. KG5RZ

    KG5RZ Ham Member QRZ Page

    The last three trucks have had a Ft857 with FC40 matching unit. Hooked to a 9 foot SS whip it would do well on 20 through 6 meters and could do well enough on 40 to allow me to check into the net and make some rag chew type contacts. Adding a 7 foot extension to the antenna improved 40, made 60 doable, and gave good enough performance to be able to check into the 80 meter nets.

    Was it the best performing choice? Probably not. It did allow quick band changes without having to stop on the side of a busy interstate to change antennas.
  5. W9WQA

    W9WQA Ham Member QRZ Page

    i use a tuner ,either icom ah4 or sg230 with the sg ? whip, forgot #!
    the best ever was about 27 feet of wire that zig zagged out back,up left right and pulled down over the windshield !!
    that was on a full size ford van. i drove in circles near s.bend and a canadian said,"never heard a mobile with less fading!!" i called it the "pow', piece of wire.
    the sg whip was well made but dissapointing in work, not so hot...

    btw,the yaesu fc40 is ok but the control cable needs real shielding
  6. M6AGL

    M6AGL Ham Member QRZ Page

    Looking inside the Fc-40 I am surprised there is no filtering on the control cables? I can see maybe some ferrite beads but they could also be protection diodes or transils. Certainly no large ferrite unless those pigtails are hiding them. Other than that it seems well made, although I would have liked it in an aluminium can.

    I like the idea of throwing out a wire, but I think I would like to see the resonance point a little easier than the FT 857 will display, as that will be more variable than a whip due to where it goes. I don't want to go through using a separate antenna tuner each time.
    I think I may be looking at an autotuner with some form of meter on it for reassurance.
  7. K0BG

    K0BG Ham Member QRZ Page

    There are no ferrites! There are small, SMD caps, but that is all. In fact...

    None of the current auto-couplers has any ferrite chokes, except for SGC, and they'r almost out of business. As a result, you must choke the coax and control lines, and even then you might have a lot of common mode. How much, depends on how well the unit is RF grounded (radials!).
    KB0MNM likes this.
  8. G6YYN

    G6YYN Ham Member QRZ Page

    M6AGL likes this.
  9. US7IGN

    US7IGN Ham Member QRZ Page

    I have come a long way from jerking off with MFJ whips and trying to work on the air on the move to effective QSOs with wire antennas outside the city. I have ICOM AH-4 and it is very useful for non resonant 7,5 meter long multiband vertical or wire full leight GP on 80


    At 40 meters, I usually use inv.V without a tuner. It is easily adjustable - just shortening or lengthening its legs.

    It all depends on what antennas you will use and under what conditions.
    AJ5J likes this.
  10. N3UML

    N3UML XML Subscriber QRZ Page

    spend the money and buy the dismond screwdriver or some facsimilee of. i currently am running a diamond screwdriver with a west mountain target tuner with an 24 year old icom 706 mk II at about 80 watts and work into europe canada and all over the us daily. Have worked spain and greece on 75. Not sure if the target tuner will work with your radio or not contact dx engineering they can steer you in the right direction. 73 and happy dxing Allan N3UML

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