Fine tuning with external manual tuner

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KC3RAA, Jun 7, 2021.

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  1. KC3RAA

    KC3RAA XML Subscriber QRZ Page

    Probably another dumb question, but I was wondering if the below method is ok for tuning in my antenna, without harming my radio.

    First off, radio is the icom 7300 and tuner is the MFJ-949e

    I found the easiest method for me is of course I turn off the 7300 built in tuner, then on the 7300 I select the SWR function (where you are supposed to quickly key the mic and the screen displays the SWR for a specific frequency or range)

    I start at low power, like 10%, key, and hold mic and I then turn the transmitter and antenna dials until SWR is at it's lowest (I previously set the Inductor dial to best setting as I know you should never move that while the mic is keyed) I seems much easier this way than watching the 949 needle. I can actually watch the bar graph of the 7300 SWR raise or lower while tuning the dials

    I just wondered if tuning this way will somehow harm the radio or is there some other way I should be using this external tuner
     
  2. KI8DJ

    KI8DJ Ham Member QRZ Page

    Find the inductor setting that seems loudest then tweak the caps until it is louder still key rig in am or FM mode with Mic at low power adjust the two cap knows until meter shows lowest swr. Using 10 watts should not hurt transmitter in the time required to achieve a match.
     
  3. W9WQA

    W9WQA Ham Member QRZ Page

    sounds good 2 me. then do the internal as a final touch up or to see if it will make a difference...
    i often/ usually use both.
     
  4. AA5MT

    AA5MT Ham Member QRZ Page

    The radio meter is the one that counts. It is always looking at a 50 ohm reference. On the outboard tuner, it no longer has a 50 ohm reference when the internal tuner is selected. It works fine in practice, as long as you remember this. The radio sees the total antenna system, where the outboard tuner only sees the antenna side as seen by the transmitter side. It is all relative.

    Tom
     
  5. KL7AJ

    KL7AJ Ham Member QRZ Page

    Yep no problem. My Johnson Matchbox, alas...doesn't do WARC bands, so I get it as close as I can with the matchbox and then use the internal tuner for "interpolation"
     
  6. KE6HXF

    KE6HXF Ham Member QRZ Page

    Okay , I have johnson matchboxes here also , With the cobra antennas i have found in the 15 meter position, I have enough range to do 12 meters and 17 meters .
     

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