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Connector losses

Discussion in 'General Ham Radio Discussion' started by Captain Kilowatt, Mar 19, 2018.

  1. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    This video shows what I have been saying all along and that is that connector losses are insignificant and using a figure or even 0.1dB for each connector is wrong. I have repeated this experiment on several occasions to demonstrate that coaxial connector insertion loss is negligible.



     
    DXman and Shadetree Mechanic like this.

  2. riverrat373

    riverrat373 Supporting Member

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    Thanks for showing us that you can't believe everything that "experts" tell us! (y)
     
  3. binrat

    binrat WDX Club Coordinator
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    I knew about the connectors. Only time I've had problems is when the el-cheapo ones corrode up from years of mobile service.
    Coax on the other hand adds up quickly, especially when QRP or near QRP portable. I'm doing HF portable (SOTA) now so I've been driven to ensure minimal losses with my KX2, coax, antenna system.
     
    wavrider likes this.
  4. MicroWave

    MicroWave Survivalist

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    In your situation is this absolutely necessary, but there are also other scenarios in which these losses are basically never negligible. These include, above all, stationary facilities and everything outside, such as Beverage antennas, free-running antenna cables, larger poles with multiple antennas installed and so on. The more connections, the greater the chance for losses. As long as everything is new, clean and dry it is true, these losses are actually negligible, but unfortunately it doesn't remain in the course of time, which may change depending on the installation effort.

    Therefore, the principle still applies today, keep the number of connections always as small as possible!
     
  5. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Yes of course keep the number of connectors to a minimum but even just one connector improperly weather proofed can yield near infinite losses. My point was that all too often people worry about the losses of this series versus that series of connector or if adding a barrel connector will introduce too much loss on HF. The truth is they won't .
     
    binrat, wavrider and Road Squawker like this.
  6. fourstringburn

    fourstringburn W9WDX Amateur Radio Club Member K5KNM

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    Nice video,

    Now find one that explains how minimal losses on HF frequencies ( 11 meters in particular) between RG213 coax and LMR 400 coax just because LMR has a higher velocity factor and power handling and why one is better on HF than the other.
     
  7. 543_Dallas

    543_Dallas Sr. Member

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    That double shield thing impresses a lot of people. They think of coax as a water hose. The more shielding you have the less rf leaks out on the way to the antenna, you'll have less receiver noise too. Common mode currents are never considered and they'll give you some crazy looks (while chuckling) when they see you're ladder line.
     
  8. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    Define better???

    What determines at HF frequencies which type of coax is "BETTER"
    Is it to be measured in a laboratory environment? If so then the specifications provided by manufactures should be sufficient.

    IS it to be measured or compared to in a real world install using an uncalibrated receiver as the reference test equipment? Then no one will ever see the difference between the two type of coax.
     
    Captain Kilowatt likes this.
  9. MicroWave

    MicroWave Survivalist

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    The most important and very first decision basis for the purchase of a cable is always the manufacturer's information. The loss factor is just as little a secret as all the other specifications that the manufacturers provide. The only problem with this is that manufacturers rarely document their measurement methods precisely, which means that the results can only be verified in the very few cases.
    If I'm allowed to give advice here, then I suggest that anyone believe what they provide as information, saving a lot of time and headaches! ;)
     
  10. StrangeBrew

    StrangeBrew Sr. Member

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    I think this is one of those areas where as good as possible should be replaced by as good as practical, seems like you could very easily wind up chasing your own tail if you really dive into this subject.
     
    Captain Kilowatt likes this.
  11. K3ACZ

    K3ACZ W9WDX Member

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    In my setups over time using new coax and connectors I usually figure about .06 db loss per connector. Gives me a warm fuzzy feeling when figuring out what my system watts may be to the antenna tip. I've used a few online calculators to figure antenna gain and such and put connector loss at .06 per connector..

    Then using radiation and distance calcs and actual drive tests I can self test my systems limits.
     

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