What am I doing wrong! IC-718 and MFJ 949E

Discussion in 'General Technical Questions and Answers' started by kd7nmn, Jul 28, 2007.

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  1. kd7nmn

    kd7nmn QRZ Member

    I picked up a used IC-718 radio and MFJ 949 tuner and cannot figure out what I am doing wrong. I have the tuner set as the instructions said to do. However, when I transmit the needles don't move at all. I've tried it up to 30 watts of power and still no movement. What am I doing wrong? I know I am getting out because I've listened to in on my handheld.

  2. K9ZMD

    K9ZMD Premium Subscriber QRZ Page


    How about telling us what band you are attempting to transmit on, what sort of antenna you are using, and what sort of handheld you are using to monitor the transmission of an HF transceiver?

    Gary, K9ZMD
    Palmdale, CA
  3. kd7nmn

    kd7nmn QRZ Member

    Yeah, I guess that info would be useful [​IMG] I am using a Yaesu VX-7R to monitor the transmission. The antenna is a Dipole and I am transmitting on 80 meters.

  4. kd7nmn

    kd7nmn QRZ Member

    Just to make sure I am right on this. The tuner does not need to be powered to work right? I only need power if I want the meter to be lit correct?
  5. N4AUD

    N4AUD Ham Member QRZ Page

    You don't need any power for your tuner. The power jack on the back is to connect 12v for the meter light.

    A J-pole on 80 meters??? What band is that J-pole cut for anyway? If it's two meters and you've transmitted with any power, I think I can probably guess what's wrong with the tuner. Does your tuner smell like smoke, by any chance?
  6. K9ZMD

    K9ZMD Premium Subscriber QRZ Page

    An IC-718 transceiver is an HF rig that works from 160 meters to 10 meters. The smallest antenna you should want to use with that rig is a 10 meter dipole, which would be 16 feet long and center-fed. On 80 meters, where you are attempting to transmit, a dipole antenna is in the neighborhood of 135 feet long. Attempting to use any practical J-pole antenna on 80 meters, even with a "tuner", is going to be an exercise in frustration. Your IC-718 is most likely to sense a tremendous mismatch and "fold back" its power to nearly zero. That is probably why your meters are not moving. I highly recommend getting an ARRL Handbook for Radio Amateurs, and learning about antennas. If a publication like that is beyond your means, then go to this web site, where you will find a wealth of knowledge about antennas, all written by one of the best.

    Meanwhile, stop transmitting into that J-pole so you don't burn up your IC-718. If you feel compelled to transmit on 80 meters before getting a decent 80 meter antenna, use a dummy load. It will get out nearly as well as the J-pole, but it will not damage your transceiver.

    If you want to begin gathering materials for an 80 meter antenna, start with about 135 feet of copper wire, 3 insulators, and some coax for a feedline. If the books and the W4RNL web site don't make dipole construction clear to you, please ask here, and we'll provide some guidance. Good luck with your new rig. 73

    Gary, K9ZMD
    Palmdale, CA
  7. K9ZMD

    K9ZMD Premium Subscriber QRZ Page


    Based on your posts here, it sounds to me like you could benefit by hooking up with a local amateur radio club. There's a lot you can learn by just talking face-to-face with some experienced hams, and even more by visiting them at their home stations. The ARRL web site lists one club within 20 miles of Laramie; it is located in Cheyenne, WY, and they call it the SHY-WY RADIO CLUB. They specialize in help for newcomers, Entry-level classes, Higher-level classes, RFI help, etc. Go here to get more details about the club. Just in case you have never visited the ARRL web site, here is a
    link to the www.arrl.org home page.

    Gary, K9ZMD
  8. W5HTW

    W5HTW Ham Member QRZ Page

    Many things wrong here.

    The 718 is an SSB transceiver, and the VX7 is not an SSB receiver. The VX7 may hear something rather garbled but not much.

    Hearing a transmitter of any kind, two feet away, is not an indication the transmitter is working.

    A J-Pole is too large to manage on ten meters, and below that, becomes rather huge.

    The MFJ tuner requires manual setup on each frequency you use it on. You can't do that if there is no output from the transceiver. It is remotely possible you could get the 718 and the MFJ to operate on ten meters with a six meter J-pole, but it would in no way be efficient and you wouldn't likely be heard more than a quarter mile away.

    Continued efforts along this line are definitely going to be fruitless, a total waste of your time, and may very well damage your IC718. And the tuner as well.

    You need to take the time to learn a very few very basic things about antennas and radio. You are currently in way over your head, and I don't say that in a mean way. You need local help, for one thing, to put up an antenna for HF, not for VHF, and to learn to use the tuner.

    Crack the book. Look in the ARRL handbook in the part about antennas. Remember your formula for determining antenna length? Use it, to figure out what size (length) dipole you need, and what a dipole is, how to construct it, how to put it up, etc. You really need a few basics, and you won't regret learning them.

    Good luck.

  9. W4INF

    W4INF Ham Member QRZ Page

    An 80m J-Pole? Wow... 130+ ft of copper pipe up in the air must be quite a sight!
  10. AG3Y

    AG3Y Guest

    Your radio might be doing exactly what it should be doing, that is, folding back the power to zero so that you don't destroy the finals!

    You definately need to hit the books! The Arrl Amateur Radio Handbook comes to mind, along with several of their Antenna handbooks. You do not need to get brand-spanking-new editions of those books, because antenna theory does not change over the years. I have books here that are 10 and 20 years old, and still answer the questions that pop up here on the "zed" all the time!

    Follow the advice given by others above. Join a local club, ask lots of questions, and listen to the answers carefully and attentively.

    I certainly hope you haven't "popped" your radio! Good luck to you.

    73, Jim
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