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Yaesu FT-847, MFJ-998 and ALS-600

Discussion in 'Amateur Radio Amplifiers' started by N5TEN, Jun 29, 2012.

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  1. W1QJ

    W1QJ Ham Member QRZ Page

    Pardon me, you seem to be new here. Many of the folks that come by with problems don't know the proper way to set up a radio,tuner and amp. No kidding! I'm awfully sorry for asking a question which many times turns out to be the problem.
  2. N5TEN

    N5TEN Ham Member QRZ Page

    I'm not using any ALC at all. MFJ called me back and I knew more than the guy who was supposed to help me with the problem. Now I have to call Mike at Ameritron back next week. My AD is not that close to the operating position. It's up 50 feet at the apex in the inverted v position with both legs at least 60 yards from the station point... one leg is probably 100 yards from here. You're right, no balun.

    I've noticed that the 847 is way different in how it excites the amp and tuner, compared to the 897. Seems more sensitive. I'll try turning the drive down even more to see if that helps.
  3. N5TEN

    N5TEN Ham Member QRZ Page

    I thought you were being a smart guy...if you were really trying to help me out sincerely, then thanks. I'm not new here. I've been a ham for 16 years. I'm just trying to work out the bugs with this one issue and the new radio. Anyway... 73 bud de N5TEN aka K6WLT
  4. KK7EL

    KK7EL Premium Subscriber QRZ Page

    It might be the new rig is putting more than the 50-60 watts the ALS-600 wants for drive and maybe the old rig did not? Also, I had an ALS-600 and never had high temp faults, but my recollection is there was a fan in the PA in addition to the one in the PS. In case my memory is stil intact, ensure your PA fan is still functional.
  5. N5TEN

    N5TEN Ham Member QRZ Page

    Thanks for that suggestion... I'll take a looksie in there. I just did the LED mod on the amp and PS and had both open...should have looked at that.
  6. K0BG

    K0BG Ham Member QRZ Page

    Don't rule out common mode! All sorts of things can happen as a result, especially in view of the fact the amplifier's PTT is routed through the 998. Have you hooked it up to a dummy load yet?
  7. N5TEN

    N5TEN Ham Member QRZ Page

    I don't have one that will handle the amp power. I'll have to buy or make one. I haven't ruled out common mode and you're probably on to something as I do have rf in the station with my monitor going off and on etc. I eliminated some of it with low loss LMR cable jumpers, and the coax out of the station is 213 to the AD. I will need to make another LMR jumper for the radio to the amp. If the issue is common mode (which it might be) what would you suggest other than the LMR, grounding (already done), and ferrites? My ground wire might be too long under the house to the grounding rod, but everything is grounded in the station.

    Choke coax balun at the base of the AD?

    I'll try the alc to the amp and see if that works. It didn't on my other radio. One more LMR jumper and then I'm at a loss on what else I can do.
    Last edited: Jul 1, 2012
  8. N5TEN

    N5TEN Ham Member QRZ Page

  9. NA0AA

    NA0AA Ham Member QRZ Page

    So you never tried my suggestion: Turn down your exiciter? Check your antenna SWR to see you are not out of spec? It still sounds like you are exceeding the SWR limits of the Solid state amplifer.
  10. N5TEN

    N5TEN Ham Member QRZ Page

    Actually, I followed your suggestion first. I did a lot of stuff that day, including turning it all down. But if it's a common mode problem, turning it all down is not solving the problem of RF coming back down the coax into the shack and screwing with my amp and other stuff. The SWR was checked via a direct sweep and it's the same as before with a 1.0 to 1.5 on tune up.

    I'm out of town right now, so the testing and such has been delayed. Plus, my wife hit a buck at 65 mph this morning and totalled her car. She's okay. I will have to put the radio on the back burner until that and work next week is dealt with.
    Last edited: Jul 1, 2012
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