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Transmitter not going up to full FWD Power

Discussion in 'Radio and Communications' started by Alex@Marvelworx, Mar 30, 2017.

  1. Alex@Marvelworx

    Alex@Marvelworx New Member

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    I just got into Radio Station Installation & Transmission.... On a project recently finished; the forward power is not going up to the maximum power (700 w); only going up to 470. When I did a dummy load with one antenna connected it would reach the peak, but after putting it up on a mast through a power divider and four antennas, I couldn't hit the peak power. That's just after the first day. What could the problem be?

    I am using an RVR TEX 702
     
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  2. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    What is the reflected power?
     
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  3. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    It really helps to get more information:
    http://www.broadcastpartners.com/website/uploads/files/products/40962.pdf
    If you can put full power into a dummy load this makes me think the transmitter is OK but:
    Some thing is wrong in the coax, divider, or antenna. Please send more information or pictures.

    Is the antenna tuned for your frequency? Not just FM band but your part of the band.
     
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  4. dave

    Dave New Member

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  5. Alex@Marvelworx

    Alex@Marvelworx New Member

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    The forward power is at 478 while the reflected is 70
     
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  6. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    It is possible that at a SWR of 2.23, the internal protective shut-down circuit inside the transmitter is reducing the output to protect the output transistors...

    Do you have a 1kW resistive RF dummy load? If so, what output do you get if you connect the transmitter to the dummy load?
     
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  7. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    I had a small 10,000. watt transmitter years ago. I remember the reflected power was about 5 watts.
    I can not remember what the big transmitters did. Too many years.
     
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  8. RadioRon

    RadioRon Well-Known Member

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    The reflected power is a bit high in my opinion. I agree with MikeMl that your transmitter may be backing off the power to keep from overheating as a result of the SWR being less than ideal. You will have to diagnose why your SWR is only fair.
     
  9. davenn

    davenn Active Member

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    I apologise in advance
    I just have to comment, it scares me that some one playing with a 700W transmitter installation doesn't know how to test his transmission line system
    and fault find

    is this a private personal system eg -- a ham radio station, or a commercial station ?


    Dave
     
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  10. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    If you have money you can get a radio station.
    In most countries you need a license.
    Back when I did this; you had to pass tests.

    You know he is trying to make a commercial station.
     
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  11. davenn

    davenn Active Member

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    you are most probably right
    Its just scary when people are doing this and they have no idea what they are doing and the dangers to be aware of

    RF currents that are producing 700W of power can do dreadful things to equipment and the human body if mis-handled, aye


    Dave
     
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  12. Alex@Marvelworx

    Alex@Marvelworx New Member

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    Thank you all for your responses... I managed to fix it.... the connector to the power divider was faulty...
     
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  13. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Thank you for telling us. Nice to know.
     
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  14. Alex@Marvelworx

    Alex@Marvelworx New Member

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    Unfortunately though there were some remarks put up by davenn And ronsimpson, That in my opinion defeat the purpose of this forum; I think I did mention that I was a newbie.... I saw quite a lot of helpful responses by other members that offered insightful remarks (the likes Mikemi & Dave) of whom when they understand a question tackle the problem not attack and criticize the one that asked. I had not divulged any information as to where I am doing it from but surprisingly, someone already had assumed the where... And how. Which I thought was of no help at all... Just a mere case of "trolling" ( bored let me go through the forum and see who to castigate; coz they are a newbie)...

    Next time please... If you don't understand how to deal with a certain problem one has presented (or you don't wanna help out) please leave it to those that do understand; or that want to share their knowledge.

    Thanks again to those that offered positive remarks... Please do keep it up
     
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  15. atferrari

    atferrari Well-Known Member

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    Hola Alex,

    In this (and other forums) I tend to watch more than contributing. Let us admit that for someone who is dealing with such a power in the final stage, your question sounds frightening, much more if you qualify yourself as a newbie. You cannot avoid that since, as you only know how limited is your knowledge on the matter in question, those contributing here know what is at stake.

    Do not complain and be objective while enjoying having your problem solved.
     
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  16. davenn

    davenn Active Member

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    you couldn't be further from the truth
    I was VERY WORRIED about you and your safety dealing with high transmitter powers and that you obviously didn't have any idea what you were doing
    This was a VERY dangerous situation for some one who admitted to being a newbie

    Dave
     
  17. davenn

    davenn Active Member

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    upload_2017-4-17_11-17-46.png

    Alex@Marvelworx .... VERY silly to disagree with the truth

    Dave
     
  18. davenn

    davenn Active Member

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    Sorry @MikeMI

    wrong post tagged, have changed rating
     
  19. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Watch out Dave, that scary current is sqrt(700/50) = 3.7A
     
  20. davenn

    davenn Active Member

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    I have had nasty RF burns on fingers from a 10W 144MHz TX
    700W is going to be much worse
     
  21. JimB

    JimB Super Moderator Most Helpful Member

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    Been there done that!

    Never done that, I still have all my fingers and hands and arms.

    JimB
     

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