IC-7200 question

Discussion in 'General Technical Questions and Answers' started by N0AVR, Dec 3, 2017.

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  1. N0AVR

    N0AVR Ham Member QRZ Page

    I'm just getting back in the hobby and bought an IC-7200 with an LDG Z-11Pro tuner (connected with the Icom cord). I have a G5RV at about 35 ft. I think I followed the tuner's directions correctly. To check SWR, the 7200 manual says to set the radio to RTTY and check the meter when you transmit. When I do this, the radio's meter shows an SWR off the charts (over 7!) Yet the tuner (it's LED anyway) shows an SWR of less than 1.5. When I transmit on SSB, the radio's meter shows a low SWR also. It's only when it's on RTTY does the meter read very high. Also, it looks like it's only happening on the lower frequencies (40 and 80m).

    Any help would be greatly appreciated!

    Ethan
    NØAVR
     
    Last edited: Dec 3, 2017
  2. N2PQW

    N2PQW Ham Member QRZ Page


    Ethan,
    Let's get back to basics... are you certain you have the IC-7200's METER set to SWR? My guess is that the LDG tuner is doing its job, and the ICOM's meter is set to POWER.

    IC-7200 SWR Measure.jpg

    If you have the METER set to POWER, and the power is adjusted to about 70%, the meter would behave the way you describe. In RTTY mode, the meter would move to the "70" range. In SSB mode, the meter wouldn't deflect much until you are speaking, and then only brief peaks.

    Check it out, and let us know what you find!

    Cheers,
    David / N2PQW
     
    KF5RRF likes this.
  3. AI4RA

    AI4RA XML Subscriber QRZ Page

    Yes, as David said, check to make sure that your SWR meter is what is showing in the display and not the power output or ALC. When checking for SWR, I prefer to put the IC-7200 in AM rather than RTTY so that not so much power is output during tuneup.

    Also, if you're using a G5RV, I would recommend making an air choke using your feedline (basically, coil it up about 6 to 10 turns at a diameter of about 12 to 18 inches) to avoid RF feedback into your shack. I've done this for years with a setup very similar to yours (inverted vee about 35 ft up at the apex) and it works very well on all HF bands, 80m through 10m and also on 6m as well.

    If you're using digital modes, make sure that your ALC shows no reading while transmitting when adjusting your computer output that feeds into the rig. This is when the rig is cold! I've found that after having run quite a few cycles transmitting digital signals, my ALC will sometimes start showing one or even two ticks on its reading when the rig is warm. Even reducing the computer control (the output slider on the computer) down to near zero doesn't change that. So I'd recommend just leaving it alone at that point and not worrying about it. However, do make sure you have no ALC reading during transmission when the rig is cold, as we should be careful to put out as clean a signal as we can.

    Just a couple of bonus recommendations there! :) Good luck and welcome back to the hobby.

    73,
    Raf
     
  4. KK5JY

    KK5JY Ham Member QRZ Page

    If you are going to use a radio in the 7000 series with an external tuner, you will benefit greatly from building one of these:

    http://www.ad5x.com/images/Articles/TuningIntfc706.pdf

    I just built one for my 7200 a few weeks ago, and it works very well. You push the button and you get something like 10W of CW output, specifically for the purpose of working an outboard tuner. This happens independent of the mode you have selected, or the power level you have selected, making the extra button very handy for a quick tune-up.

    Other radios have integrated this as a built-in feature that you could activate from an existing button, but on late-model Icoms, you have to make your own button.
     
  5. KC3RN

    KC3RN Ham Member QRZ Page

    No need to do this with the OP's setup. His LDG tuner is connected to the radio with the Icom interface cable. Pushing the tune button on the tuner will automatically switch the radio to CW and reduce the output to about 8 watts. The DIY tuning interface is really only necessary if you're using a manual tuner, or a "generic" auto tuner.
     
    KK5JY likes this.
  6. KK5JY

    KK5JY Ham Member QRZ Page

    That's a very good point. I had forgotten about the "Icom cable" that comes with those tuners.
     
  7. N0AVR

    N0AVR Ham Member QRZ Page

    Thanks everyone! I reset the tuner and made sure the meter was set to SWR and everything seems to working ok now. Raf, thanks for the advice on the G5RV.
     
    N2PQW likes this.
  8. N0AVR

    N0AVR Ham Member QRZ Page

    Thanks Raf. I'm going to make the choke tomorrow. 73 Ethan
     
  9. W5DXP

    W5DXP Ham Member QRZ Page

    We cannot wind an air choke that is effective over all of HF. Take a look at Steve's common mode web page and you may decide to install an effective ferrite toroidal choke on that G5RV. The G5RV that I bought in 1988 came with a w2du choke-balun.

    http://www.karinya.net/g3txq/chokes/
     
    W9AMM likes this.

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