600 watt HF Linear Amplifier Project

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

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  1. WB2GCR

    WB2GCR Ham Member QRZ Page

    Hmmm... I thought I knew that larger gauge wire had higher inductance...
  2. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

  3. WB2GCR

    WB2GCR Ham Member QRZ Page

    Odd... in audio speaker cables, when you start to get thicker than 12ga the inductance starts to rise and
    the HF response starts to droop. Which is why "jumper cables" or "welding cables" are not recommended
    for speakers that run into the higher freqs.

    I'll look at ur link.
  4. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    I would like to see the speak cable data....
    That goes against the formula for inductance.
  5. SWL37632

    SWL37632 QRZ Member

    Thanks Sue....I was out of pocket the last day or so and couldn't respond to the follow-on questions.. BW
    AF6LJ likes this.
  6. SWL37632

    SWL37632 QRZ Member

    I'd like to see this data also. Note...there's a difference between solid wire and multistrand wire conductor of the same equivalent gauge for an AC type signal/circuit. Depending on the weave or lay type of the multistrand conductor 'bundle', the fundamental conductor parameters can be different. You also need to consider the operational frequency range of interest and any 'sneak' paths for unwanted currents.....but now I'm being a 'purist'... BW
    AF6LJ likes this.
  7. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello All,

    I am back from the Xenia Hamvention. Bottom line:

    I had a great time and it will take a week to clean the mud from the outside and inside of my truck. The flea market was brimming with treasures looking for a new home and I have never seen so many vendors at Hamvention before. I sold 2/3 of the stuff that I brought with me brought home a few things that I didn't know that I couldn't live without.

    Now it is time to finish this project up.

    AA7QQ and AF6LJ like this.
  8. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello all,

    I am at a frustrating place now on this project. A metal box was made to cover the Icom interface board but it made no difference with my relay chatter problem on 160 meters.


    Moving this board away from LPF filter and changing it's orientation ninety degrees to the front panel helps but doesn't eliminate the problem completely. Another thing that I noticed is that the position of the short copper covered ribbon cable makes a difference as well but only if the interface board is perpendicular to the front panel. Otherwise the 160 meter LPF relay chatters with very little drive power and moving the ribbon cables around doesn't do anything to improve the situation.

    The worse thing is the power and swr LCD is acting up again. The indicated power goes down and the SWR increases as I move up the bands where as before I started fooling around with the interface board the power and swr reading matched the linearity that the Telewave was showing me.

    I stopped for the evening to ponder over these problems.

  9. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    I have some thoughts.
    Remove the Icom interface board and run the amplifier in manual mode, see if the problem persists.
    Once you have made the amplifier work without the interface, reinstall it and see if the problem is still there.
    If it is try a proper ferrite bead on the cable close as possible to the outside of the interface housing.

    If this approach doesn't work your options may be limited.
    Make a mock up rear panel and route only the output wires to a connector on the rear panel, see if you can get the interface to work as an external device. If you can try mounting the housing to the mock up.
    If it works there I think I would go with it, make a new rear panel, a new housing for the interface box and be done with. My biggest fear has been from the beginning is that you have too much in too small of an enclosure.
    Don't give up there are no doubt alternatives I have not explored, and one way or the other you will have success.
    WA9WVX likes this.
  10. KV4PD

    KV4PD Ham Member QRZ Page

    Don't forget, it has to be oxygen-free copper. Any audiophile worth his salt knows that.....
    AF6LJ likes this.

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