10 Meters, CQ CQ, is anyone on?

Discussion in 'Ham Radio Discussions' started by KG5MLS, Mar 13, 2017.

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  1. W0VRA

    W0VRA Ham Member QRZ Page

    You're funny.

    upload_2018-4-16_14-4-44.png
     
  2. K1FBI

    K1FBI Premium Subscriber QRZ Page

    So you are paying attention and learning. Glad my efforts weren't wasted.
    Now bookmark that link and create a Ham Radio folder.
    One thing I've learned over the years is there is no need to reinvent the wheel.
     
    W0VRA likes this.
  3. WE4E

    WE4E Premium Subscriber QRZ Page

    Here's a little study material for you. The datasheet for Times Microwave LMR-400 is here, and the datasheet for Belden 9258 RG-8X is here. If you peruse those, you'll see specifications for losses. Now, unfortunately, they only list a couple of common frequencies, but taking 50Mhz as an example, LMR-400 specs a loss of .9db/100 ft., whereas 9258 lists 2.1db/100 ft.

    The takeaway, in practical terms, is that RG-8x has ~twice the loss or more n equivalent length of LMR-400. Loss works both ways, transmit and receive. It reduces inbound signals to the receiver and output power to the antenna. It works exactly the opposite of antenna gain. 3db of gain is a doubling of the power. 3db of loss is half. It affects all radio signals in the same way, although cable losses generally become greater as the frequency increases, i.e. loss at 10mhz will be less than at 30mhz will be less than at 100mhz. So cable that is ok for 40m may not be a good choice for 2m.

    upload_2018-4-16_14-6-19.png

    Since you're talking about different lengths in addition to different cable types, the results will be, well, different. 20ft. of LMR-400 will have a loss of ~.18db. How did we get that? 20ft is 20% of 100 ft., so .9db * .2 = .18. 50ft. of 9258 will have ~1.05db loss. Same math.

    Since 3db of loss is ~half, clearly, .18db is for all practical intents, none. 1.05db is ~16%. In real life 1db isn't a huge deal most of the time. There are generally bigger fish to fry.

    So in your specific case, if you have 20ft. of LMR-400 and the installation permits, it's the better choice. If you have 50ft. of RG-8X and that's appropriate for the job, use that, it will be fine. If you have the RG-8X but don't need all of it, consider cutting it and attaching a new connector.

    Either way, hook it up and get on the air.
     
    WA4KCN likes this.
  4. K1FBI

    K1FBI Premium Subscriber QRZ Page

    Or you could just go here:
    http://www.qsl.net/co8tw/Coax_Calculator.htm
     
  5. WD0BCT

    WD0BCT Premium Subscriber QRZ Page

  6. VA3DLO

    VA3DLO Ham Member QRZ Page

    Ok tnanks for info...
     
  7. WA9SVD

    WA9SVD Ham Member QRZ Page

    Sorta weird, but I had an experience some years ago, on the 6 M calling frequency. After listening on 50.125 MHz for over ten minutes, I sent out a short CQ. Sure enough, I was chastised by at least two local others for using the calling frequency, because THEY were monitoring it for openings... DUH? What is wrong here (or was there?)
     
  8. ND6M

    ND6M Ham Member QRZ Page

    Perhaps, you received their ire (that was built up) due to "certain" people using the call freq to "run" stations.

    I'm sure a CQ on .125 followed by "listening up 10" would not have been unacceptable.
     
  9. N4BBQ

    N4BBQ Ham Member QRZ Page

    Well, he pretty much caused the FUNDING of The Internet. Here's a history lesson for you. I hope facts don't confuse you too much.

    https://en.wikipedia.org/wiki/High_Performance_Computing_Act_of_1991

    Just think of all the JOBS and $$$$ this system that was funded by the evil government has created.

    A terrible situation...
     
    W4NNF likes this.
  10. WA9SVD

    WA9SVD Ham Member QRZ Page


    Easy enough to go "UP" once contact was made. I just don't get your logic. If NOBODY calls on 50.125, Then there is nobody to listen to. But the CQ would still have to be made @ 50.125; that is where even DX will CALL.
     

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