ANTENNA Tuner Correct Specs But Misleading

Discussion in 'Ham Radio Discussions' started by KC3EPA, Apr 15, 2018.

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  1. KM1H

    KM1H Ham Member QRZ Page


    It was proven by many that a 50's era Johnson Viking I and II could and did load up those sort of things without any outside help.

    Carl
     
  2. KA0USE

    KA0USE Ham Member QRZ Page

    i had a club loaner johnson viking ranger II.
     
  3. KM1H

    KM1H Ham Member QRZ Page

    But only the V-1 and V-2 had a roller inductor ganged to the Tune cap and a wide rang Load circuit. I used to work afternoon commuters on 160 AM with a V-I using a 40M dipole and 72 Ohm twin lead, no ground either....Also used on 80, 11 (still a ham band), and 10....didnt know better when still in HS in the mid to late 50's:eek:.

    These days I have a V-1, V-II CDC, Ranger, Valiant, and Adventurer.
     
  4. KC3EPA

    KC3EPA Ham Member QRZ Page

     
  5. KC3EPA

    KC3EPA Ham Member QRZ Page

    20 meter vertical MFJ 1979 5 meters high
     
  6. KC3EPA

    KC3EPA Ham Member QRZ Page

    Antenna is 5 meters high and used 5 watts to try
     
  7. KC3EPA

    KC3EPA Ham Member QRZ Page

    In any case it works with coil
    Yes the efficiency is down but not going to be able to put 1/4 wave 40 meter antenna on car.
    I will settle for the 5 meter as HOA is not allowing any antenna.
    The MFJ 1979 is antenna the tuner 939MFj

    I understand hamstick or any shortened antenna will have lower efficiency
    I understand the swr is still there with tuner but hopefully PA sees a 1/1 and the output from tuner still sees mismatch but main unit is safe

    In any case it has a coil now for loading a 1/8 wave vertcal which is actually an off center match when you consider the car is other side of dipole.
    If it were a large truck with length than it probably would load.

    It did load in my Honda Pilot just not my accord.

    I have been using on 20 meters during day and have gotten everything to eastern Europe and California with 5 meter antenna.
    I used a 20 meter hamstick before and worked just as far but now get much better reports

    I am forced to use the 5 meter antenna and it is working OK with a home brew coil.

    I was just hoping the MFJ 939 tuner was beefy enough for my use.
    I did get a 3/1 so it does work
    I did try a friends tuner manual with big roller inductor and it worked
    It also worked on my friends 20 meter vertical at his house with MFJ 939

    I was just hoping the 6 to 1600 matching would apply inside car
    In any case it is great from around 30 meters to 10 and that saves time getting out and retuning.


    The coil for 40 takes about 5 minutes to remove or attach and the tuner will give me 20 or 40 with no problem with coil if need be.
     
  8. KK5JY

    KK5JY Premium Subscriber QRZ Page

    That will work fine. Concentrate on lowering ground losses. See K0BG's website for a good discussion on how to do this.
    With a good RF counterpoise (a well-bonded vehicle body in your case), you can make a λ / 8 antenna like the 1979 reasonably efficient on 40m. With a shortened whip, the efficiency is more dependent on ground losses and coaxial cable losses. So do the best you can with those two areas.
     
  9. KC3EPA

    KC3EPA Ham Member QRZ Page

    Agreed that is why it liked the Honda Pilot
    Has a much larger surface area in length and diameter

    Coaxial cable is pretty short but I can take it from 15 feet to about 7
    I am using trunk lip
    Center of roof could possibly good place
    I did notice some resistance from shield to body in order of about a little under one ohm
    I did add a grounding strap and that resistance did go away
    Right now I am using homebrew coil but I like the auto uner as it keeps me in one seat and inside car.

    I was thinking 1/8 wave would be much better than a 40 meter hamstick which has like low efficiency
    You are very savy and have open ears and mind.

    I was hoping a for a decent efficincy based on it being 1/8 wave which is not shoddy for a mobile.

    The interface cable did have one wire that was broken but MFJ assured me it is only memory related and they are sending new one.

    Thank you for insight.
     
  10. W2AI

    W2AI QRZ Lifetime Member #240 Platinum Subscriber Life Member QRZ Page

    Stick to VHF/UHF operation in the mobile. As heavy RF losses are associated with electrically and mechanically short HF antennas--you are, in essence, running QRP (a few watts) into an inefficient antenna.
     

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