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

    Hi Reg,

    Well thank you for the comment. I always appreciate when someone shows me how they did a particular task or technique and this is a great site for sharing ideas so I thought I would do my bit.

  2. N1OOQ

    N1OOQ Ham Member QRZ Page

    This level of detail is perfect. Those of us who build and experiment are always looking for ideas. Those of us who don't probably aren't reading this.
  3. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hi Tom,

    Thank you for the comment and you may be correct, builders tend to like to learn new tips and tricks. I know that I do.

  4. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello All,

    One of the tasks that I needed to complete sooner than later was to wire the selected band indicator LEDs. For the mock up board I mounted a string of Green LEDs on a project circuit board but in the cabinet the LEDs are going to be Blue and arranged in a semicircle. I have been thinking for a while about the best way to mount the lights and neatly wire them. Scrounging around in my box of project circuit boards I found this one that I think I have had for 20 years or more.


    Holding it up to the inside front face of the cabinet I marked the placement for the band selector switch hole and LEDs. Then I drilled holes for the band selector shaft to pass through and the LEDs to mount. It took about an hour and a half to solder the connections and test the board. Now all I have to do is to secure it to the cabinet.


    In the picture above you can see my mock up LED selected band indicator board below the one that will be mounted in the cabinet.

    A front and rear view of the selected band indicator board positioned in the cabinet.


    LED selected band board.JPG

    My plan is to mount this circuit board to the aluminum "L" shaped bracket that the holds the band selector switch.

    Until next time.

    AF6LJ likes this.
  5. AA7QQ

    AA7QQ Ham Member QRZ Page

    Hackalicious !!! That's a compliment.

    AF6LJ likes this.
  6. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Thank you Ed.

    AF6LJ likes this.
  7. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello again.

    The LED selected band board is now mounted on the "L" shaped bracket and the whole assembly is back in the cabinet. The brass standoffs were made from thick wall tubing that you can get from a well stocked hobby shop if you are lucky to have one nearby. The one that I frequent is only a mile from my house.

    I cut the brass tubes to length, tapped both ends to take 4-40 pan head screws, then mounted the board to the bracket. The whole assembly mounts to the cabinet with four screws.

    LED selector BD mounted.JPG

    This evening I drilled two holes to accommodate the high SWR fault LED and PA input over drive protection fault condition LED. The power amplifier was moved from the mock up board to the cabinet as well.

    PS-PA-LPF boards in cabinet.JPG

    The hinged bottom plate will the surface where the input protection and power supply boards will be mounted along with Mu metal shield to keep RF away from the digital displays.

    Cabinet with bottom open.JPG

    Along with those boards I still have to find places for the transmatch and high SWR boards, the bias relay board, the current shunt, and the RF output bypass relay to name a few.

    Bottom line, I still have a long way to go.

    AA7QQ and AF6LJ like this.
  8. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    Very nice, construction is coming along nicely.
  9. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Thank you Sue.

  10. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hi All,

    A quick note to update you. Just about everything has now been relocated to the cabinet.


    I have the switching power supply wired to the power supply protection board and from there to the +12 volt power supply daughter board. You can see it in the picture below along with the 50 amp shunt for the digital current display.


    The relay connects the bias voltage to the PA board during transmit. I am trying to keep the cable runs between the circuit boards mounted on the hinged bottom panel and the cabinet itself to a minimum. Keeping that in mind everything that requires the +15 volt supply is on the bottom plate and everything needing +12 volts is mounted inside of the cabinet. This evening I look some time to wire the +12 volt supply voltage to the digital displays, LPF diplex board, the selected band LED board, and the power LED.


    It is hard to see because of the camera flash but the voltage and current displays are also lit. I am using the dark gray smoked Plexiglas panel in this picture and the blue LED looks kind of like a star in the night. The picture really doesn't do much to show the effect.


    But I really like it.

    Another picture of the cabinet on its top with the bottom panel swung open.


    This one is the bottom panel closed up and you are looking in from the top of the cabinet. To say the least I am very pleased with the layout so far.


    Have a good evening

    N1OOQ likes this.

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