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Radios auto tuner keeps hunting and a fix

Discussion in 'General Ham Radio Discussion' started by Tallman, Jun 1, 2017.

  1. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Been a long while since I went mobile with my ham radios. I use the MFJ antennas that resemble the fire sticks. Even though they were tuned with my antenna analyzer, the radio tuner will still hunt the lowest SWR when keyed. I hooked up a radio I hadn't used for a while and the tuner kept hunting with out stopping.
    I hooked up the analyzer and the SWR was almost perfect. Now I was confused. (Not unusual anymore)
    Trying to remember if I had this problem on this radio before I checked my notes and had no troubles listed for this radio. I got my 50 ohm test load and tested it again and lo and behold the search was on. After about ten seconds it finally locked down. I tested on the other bands and the process repeated on all of them.
    I retested each band again and lock down was less than a 1/4 of a second for each one.
    Went out to the mobile and it worked perfectly. By tuning it back up on a resistive load it, I guess centered the tuner on the frequency on a resistive load. it must have been 7 or 8 months since the radio had been used as the base unit and not in the mobile. The base antenna check out okay just a little high on 20 meters.

    So if you have one that's hunting take it to a dummy load and see if that fixes it. It could save a repair cost you don't need.


     
    #1 Tallman, Jun 1, 2017
    Last edited: Jun 1, 2017

  2. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    That's strange. Tuning into a dummy load should have nothing to do with clearing any issue. Are you sure you didn't have a loose coax connection you overlooked and it was tightened when hooking the tuner back up to the antenna? A loose shield connection and stray RF can cause tuner hunting.
     
  3. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Cables were the first thing I checked. The tuner is loaded with reactive components.
    The very function is to react with the antenna to get SWR minimized. Running it into a resistive load forces it to go back to center and nonreactive state. Sort of like a wheel alignment eliminates pulling to one side.
     
  4. fourstringburn

    fourstringburn W9WDX Amateur Radio Club Member K5KNM

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    Break down and get a Little Tarheel screwdriver antenna and remote tune all bands (model dependent) with 1 antenna.
     
    RatsoW8 likes this.
  5. RatsoW8

    RatsoW8 Supporting Member, W9WDX ARC Member - WD8T

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    I agree with CK on rf getting into the tuner. I used to use an LDG tuner that would hunt for a tune when it didn't need to and just grind until I bypassed it. Just turn off the tuner and check the swr.
     
  6. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Yeah I know how the tuners operate. I have an automatic tuner (Yaesu FC-40) but have NEVER had an issue like that where I had to tune into a dummy load to "reset" the relays to prevent hunting. I have had it fail to tune and simply go into bypass mode but that was due to an extremely highly reactive antenna with a very low impedance. I would have thought your tuner should have been able to find a match after running thru all the combinations even if it took 10 seconds or so to do it.
     
  7. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    You guys are probably correct. I don't know if the issue was because of no activity for a long time, going from base to mobile for the first time. It could be I misinterpreted the results, or my cat had a hair ball, or feed back through the DC power, I wasn't holding my tongue right the Band-Aid on my finger fell off, Rod Serling was in the house...
     
  8. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    He's a frequent visitor to my house as well as Mr. Murphy. :D
     
  9. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    They live here and I guess when things are working right they are out visiting other people. Although Mr. Murphy is behind on his rent......
     
    Captain Kilowatt likes this.

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