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Best Moblie Antenna for OTR Truck

Discussion in 'CB Antennas' started by ctvanover, Oct 9, 2016.

  1. HARDROCK

    HARDROCK
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    Lol. .. that is funny.
    Just cut the rug out from under neath us.
    Nothing like the good ole boys from Texas.
    The truth hurts some times.
    Every one Have a Great Thanksgiving.




    Tony 73
    Your delusional. CTR has made statements that contradict your beliefs and you're too full of yourself to realize that.

    #91543_Dallas, Tuesday at 12:37 PM

    543 I stated above The truth hurts some times refering to me and rabbiporkchop post 88 you made.

    I had no intentions of degrading you being from Texas
    As far as .You and I all is well as far as i am concerned.

    Tony 73
     

  2. 543_Dallas

    543_Dallas
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    Were good, just different points of view and maybe a few misunderstandings. Like I said before I don't take this stuff too seriously. I thought you were trolling and it was fun.
     
  3. HARDROCK

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    Thanks 543.

    The only sure way to determine an efficiency change is to measure the efficiency directly

    or in the most direct way possible. Base impedance is NOT the most direct method, but field strength and applied power certainly is. CTR post 55.

    I would like to see info on tuning with a FS meter.
    I could tell Db and probably all of us on this forum would like to discuuss several issues with CTR.

    Too bad his time is limited. He is a walking encyclopedia.
     
  4. 543_Dallas

    543_Dallas
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    Yep, that's too bad. Good luck with all of that.
     
  5. HARDROCK

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    M. Walter Maxwell said:
    THIRD, we should become more familiar with the universally known, predictable behavior of off-resonance antenna-terminal impedance and its correlation with SWR. This knowledge provides a scientific basis for evaluating SWR-indicator readings in determining whether the behavior of our system is normal or abnormal, instead of blindly accepting low SWR as good, or rejecting high SWR as bad.

    Db this is from post 80.

    Which made me think about the conjugate match.
    Is a conjugate match when a matching device is placed at the antenna feedpoint or
    in the vehicle at the rig ?


    This quote also is of value.

    Maybe you can comment on this.
    I think this is a very helpful statement.
    The antenna can be tuned with a FS meter. which can lead to maximum power radiated.'
    Do you agree ?
     
  6. The DB

    The DB
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    Yes.

    I know, I said yes to an or question...

    It doesn't mater where in the system said match is, it functions using the same principles. An easy way of explaining the conjugate match is it is a system that provides a complementary reactance to an antennas feed point reactance to create resonance. Resonance, remember, is a balance in inductive and capacitive reactance. This is one way of achieving said balance.

    So to put it another way, lets say an antenna presents 100 ohms of inductive reactance at its feed point. If you use a matching systems to to counter that reactance with 100 ohms of capacitive reactance, you have balance, and by extension resonance. It doesn't matter where that matching system is, as long as the antenna is provided an equal amount of reactance of the opposite type than its its feed point presents. This is the basis of all matching networks, at least as far as reactance is concerned.

    What many people look for when tuning mobile CB antennas also fits with the conjugate match, and is more of a special case of said match. As we know a conjugate match presents a load (antenna) an equal amount of the opposite type of reactance to achieve resonance. If you have an antenna that presents zero capactive reactance, and balanced it with zero inductive reactance (or vice versa, same thing) it is still a balance of reactance, is it not? This describes standard mobile CB antennas and their ability to have a very low SWR without the need for a separate matching device. It is also the limit of knowledge that many people have when it comes to resonance. In reality, it is nothing more than a special case of the conjugate match, and it had a name, the Z0 match.

    I don't find it strange that, as far as mobile CB is concerned, many think that limited knowledge is all there is to reactance as it isn't difficult to make a mobile CB antenna that can be tuned as such. The fact that pretty much all base CB antennas have a matching system built in to their design that makes them act very similar, from a tuner's perspective, to said mobile CB antennas doesn't help either. For people who stay within the very narrow range of frequencies that is the CB band, living under this limitation is enough for them to do what they need/want to do effectively. It doesn't matter that in the grand scheme of things they are wrong, they simply don't need the additional knowledge for their situation, and that is fine. The problems arise when certain things are said with this assumption, and others believe them unconditionally. Many myths that persist to this day were created that way. Perhaps the biggest problem is when they assume the special case their experience limits them to is all there is...

    I see what you are doing here. Just a note, I don't like being used in this way. Don't do it again.

    Anyway, yes, a field strength meter, used correctly, is the best way to determine an antennas maximum radiation point for a given frequency. This is because it doesn't concern itself with things like SWR or resonance, neither of which is guaranteed to line up with said point. It work by taking a direct measure of field strength, and because of that it takes into account things that no antenna analyzer can get readings on. In essence, it is the ultimate lie detector when it comes to an antenna's maximum radiated signal point for a given frequency. The hardest part of using one properly is making sure it is far enough away that the near field doesn't effect the readings, and being far enough away from it that you also don't affect its readings... I use one in conjunction with my VNA every time I tune an antenna. It is my opinion that anyone who wants to buy an antenna analyzer should get experience using a Field Strength meter first, but no one seems to listen to little ole me...


    The DB
     
  7. HARDROCK

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    Very good. I by no means am playing you off what ctr stated above.
    I am just trying to Learn.
    I agree with what you and m0gvz said earlier. I and others are not on the same level. as you 3 are.

    I believe you all have good solutions , But at the same time it has to be simplified to a point of understanding for some of us.

    Like 543 stated i was using others work which he was 100% correct.

    G3tso states the same as you and i agree on , maximum FS.

    Maybe i am wrong by saying tune for resonance.

    The 5ft firestik i put on was tuned for lowest swr on 27.185 1.2 swr R 48
    I then added the transformer at the antenna feed point.



    The swr at the radio was then 3.1 .

    I adjusted the tuning screw all the way down.

    This is when the swr went flat the internal swr meter dont move.
    I placed the fs meter on the hood of truck, the antenna is on the back.
    Roughly 6-8 ft distance.

    The fs meter pegged the scale.
    This is when the recieve and transmit i coud tell was better.

    Now can I explain why ? No


    A short mobile HF whip is another example. If the loading coil is adjusted to tune the antenna to resonance, the load impedance will often be very low (20 ohms or less). A matching transformer at the base is often used to convert this low impedance to 50 ohms in order to provide a low SWR on the 50 ohm feed line.

    Note that some of the wound fiberglass whips are pretty close to 50 ohms at resonance. That is because the high losses in the wire and ground system add to the feed impedance. Lets say the impedance at resonance is 25 ohms. If the loss is also 25 ohms then the total impedance is 50 ohms and the SWR is 1:1. Nice match, but half the power is being radiated and the other half is being converted to heat.

    This is the best way i know how to explain my situation.
    The last sentence i believe is true.

    I have proved this by experience.
    Am i trying to say this is best ? Yes in my opinion.
    But i do not want to argue about it .
     
    #112 HARDROCK, Dec 1, 2016
    Last edited: Dec 2, 2016
  8. Riverman71

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    I have followed the technical discussions in this thread with great interest. F/S meters, SWR meters, and Analyzers aside, would the following be an acceptable alternative tuning method?

    Adjust the antenna in increments (transmitting each time) as a fellow operator (in a mobile 5 miles away or a base station 10 miles away--exact miles don't matter; just so they are not nearby) listens and watches his/her S Meter. Stop when reported performance is at its peak.

    Then, if so inclined, take meter readings and see what they say.
     
  9. HARDROCK

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    I had the same thought Rm 71 . I have not had time to do further testing.
    There are so many variables in every situation.
    In my situation lack of ground plane is the biggest problem via vicegrip pliers mount , not enough metal underneath the antenna .

    That is because the high losses in the wire and ground system add to the feed impedance.

    So in my opinion Yes why not just use the FS meter .
    When time permits i will do some more test and post it.

    It is alot cheaper than the analyzer . I have a old radio shack fs meter.
     
  10. The DB

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    The problem with using a remote s-meter is, even for radios that are far more expensive than the most expensive CB's, they simply aren't accurate enough. To give an example, an s-meter, properly calibrated, will show an additional s-unit when it receives four times the power as the original signal. That is a lot of power difference, far more than the difference you will see when tuning an antenna, and that is assuming the s-meter is accurate to begin with, and factor in that far more expensive and much higher quality ham radio s-meters are not even really that accurate. That is also before factoring in the ALC circuit and it modifying the incoming signal strength. It would be great if it worked that way, unfortunately, its just not a reliable method.


    The DB
     
  11. HARDROCK

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    What type FS meter do you use ?

    (6) If a suitable matching network cancels all the
    reactance developed by a non-resonant-length
    radiator and a random-length feed line that is mismatched
    at the antenna feed point, the antenna system
    is resonant, the mismatch effect is canceled,
    maximum current flows in the radiator, and all the
    power available at the feed point is absorbed by
    the radiator.

    I found the above by maxwell.
    I believe this is why i now have maximum smoke.

    C o u n t d o w n for a J o u r n e y f r om M y t h o l o g y t o R e a l i t y 2-3

    This is from the maxwell pdf the entirety need be read.
     
    #116 HARDROCK, Dec 2, 2016
    Last edited: Dec 2, 2016
  12. Riverman71

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    I understand.
    And if it takes four times the power to gain one S-unit, there's no sense in driving oneself crazy over less than perfect SWR, Impedance, or F/S meter readings when running a barefoot 3.5 watt CB.
     
  13. HARDROCK

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    Db i am waiting for CTR to respond to your comments.
    I assume he is busy.
    You made some very important points.
    Is his credibility really valuable ?
    I would have though so ....

    Tony 73
     
  14. M0GVZ

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    There is none. Without test equipment, even a basic SWR meter, you cannot do it.

    Not good enough. The meter and the human eye isn't sensitive enough or, more importantly, consistent enough at one level that the differences being measured can be measured accurately enough. A friend of mine does commercial VHF radio installs and runs repeaters. The Kenwood radios he has can be set to display the signal strength being received in dBm. With a repeater 10 miles away clear line of sight listening to the control channel of the trunk system he uses the dBm being measured by the Kenwood receiving it will go up and down by a few dBm. You would need a signal difference of at least 3dBm to notice any difference with any certainty and you have to end up with some really bloody high SWR to get that amount of change in a mobile install. Even a 10:1 SWR mismatch on 27MHz with the 15ft of RG58 a magmount typically comes with results in a loss of less than 1.5dB. You'd notice that mismatch more at your end than the other station would because your S-meter needle wouldn't go up as far as it normally did when you TXd.

    You can end up with a signal received at the other end strong enough to be perceived as the maximum that can still end up with a SWR of above 3:1 at the transmitter. I can guarantee that I could alter the tuning of an antenna from 3:1 to 1:1 and back to 3:1 and you'd not notice the difference at the other end.
     
    #119 M0GVZ, Jan 8, 2017
    Last edited: Jan 8, 2017
  15. Riverman71

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    Good to know.
    Thank you.
     

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