600 watt HF Linear Amplifier Project

Discussion in 'Homebrew and Kit Projects' started by KD8UYQ, Feb 9, 2017.

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  1. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello Sue,

    The transceiver and LDG antenna tuner work perfectly together on all bands as long as the amplifier is shut off. Are you suggesting that I add my watt meter to the output of the antenna tuner then test the bands again? Also, I suspect that you want me to monitor the reflected power while I am testing not the forward power so much.

  2. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    That was not what I meant to suggest. ....
    The tuner should be last.
  3. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello dear lady,

    OK, let me play this back to you. The setup would be transceiver to watt meter; output of the watt meter to the input of the auto antenna tuner then out the antenna tuner to my dipole. This test would be done with no interconnecting grounds and no chassis grounds to a common point plus all the RFI isolators removed as well. Does that sound correct?

    AF6LJ likes this.
  4. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Now that I have learned more about the RFI condition in my shack. I agree that the sub-woofer hum and TV in the workshop turning on are separate issues to be addressed, or not, at another time. The good news is my CO monitor doesn't alarm anymore when I am operating on 80 and 40 meters.

    It is too soon to tell but I think by adding the common mode choke to the feed point of my antenna I may have lowered my 80 meter noise floor by 2 S units. I need to operate on 80 meters over the next few days to see if that statement holds true.

    Sue, I also agree that running that copper ground strap out the second story window and down to the ground rod was a futile effort but several other folks insisted that I needed to have a good earth ground and that distance wasn't going to be an issue. It would cure my ills.

    Testing proved otherwise. It didn't fix anything but it didn't make it worse either.

    Today is grounds keeping day and I have other projects that need attention this week but I will report back when I have run those tests.

  5. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    Yes because sometimes ground loops can be a problem.
    WA9WVX likes this.
  6. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    The only thing a good earth ground is going to buy you is better lightning protection.
    But that is a relative statement. If you get hit there is little or nothing you can do to protect your gear, or your home for that matter....
    SWL37632 likes this.
  7. KD8UYQ

    KD8UYQ Ham Member QRZ Page


    Remember though that I placed RFI isolators between the transceiver and linear, the linear and the antenna tuner with no improvement but I like your idea about starting basic then adding things to see what changes.

    AF6LJ likes this.
  8. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    Get rid of all that stuff.
    Start from bare nothing.......
    WW1WW likes this.
  9. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Roger that. Bare bones it is then.

    AF6LJ likes this.
  10. SWL37632

    SWL37632 QRZ Member


    Kinda lost the thread here, but you mentioned that your ground line was about 20 feet long up a second story...don't remember if you detailed it out in this thread...may have missed it.

    First, agree with Sue on starting from scratch with these grounding issues.

    Back to the grounding line....if you are using a braid (flat, circular, oval ...whatever) you basically have an inductor to ground at RF. Recommend that you change it to a continuous flat copper sheet material if possible, as wide as practicable....understand the HOA aesthetic issues. If flat sheet material is not possible, soft copper tubing with as large a diameter as is acceptable in your specific case.

    Suggestion 2: last year discovered a surprise at my shack....the 120 vac lines were reversed at the duplex outlets in the room since the house was built 50 years ago....yup, neutral was wired as hot and and hot was wired as neutral.... shack equipment / pc's etc were originally connected between 2 of the outlets....ouch. If you haven't done it already, recommend that you check the wiring polarity of any outlets in use, also verify that outlets are on the same circuit breaker (phase differential issues) albeit minor in most cases, but in my case proved to be problematic.


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