Splitters/combiners

Discussion in 'Amateur Radio Amplifiers' started by AA7QQ, Jul 3, 2017.

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  1. WW1WW

    WW1WW Ham Member QRZ Page

    Or he could just buy it all made for less than he could build it.
    https://www.aavid.com/products/liquid-cooling/416501u00000g
     
  2. AF6LJ

    AF6LJ Ham Member QRZ Page

    I have done hand lapping on heatsinks and waterblocks for computers, it takes patience and time.
    That is how it is done, even after it someone takes a surface grinder to it.
    There are some really good territorials on lapping on YouTube.
    Remember the surfaces need to be flat not parallel.
     
  3. WW1WW

    WW1WW Ham Member QRZ Page

    He is purchasing ready made pallets, they already have the transistors mounted on flat plates.
     
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  4. AF6LJ

    AF6LJ Ham Member QRZ Page

    Then all he needs to do is lap in the heatsink .
    I wasn't sure if they came with spreaders or not.
     
  5. AA7QQ

    AA7QQ Ham Member QRZ Page

    I have already ordered thermal transfer epoxy, but thank you for the offer.

    Ed
     
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  6. AA7QQ

    AA7QQ Ham Member QRZ Page

    Well, this is an experiment. I will have about 1 1/2 GPM per 300W pallet flowing. Total dissipation of the LDMOS is 500 watts, so at full tilt boogie, I will only have to remove 200W.
    The fans will be there for a backup.

    Ed
     
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  7. AA7QQ

    AA7QQ Ham Member QRZ Page

    Well, I stopped at Lowe's on the way to work. Picked up a 25' coil of 3/8" .020 wall tubing. Cut a piece off. squished it a bit in the vice to the width of the mid point of the heat sink. Grabbed a piece of scrap 1/4" steel. Grabbed a scrap piece of UHMW & sanded it to .315" (Width of expected depth)
    Worked out very well.
    I will be manifolding these & will try a simple one first to see if it flows equal & if not, I will restrict flow to equalize them. It pops out very easy, so, I ordered some heat transfer epoxy.

    Ed
    Heat sink large.jpg
     
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  8. AA7QQ

    AA7QQ Ham Member QRZ Page

    I like to build. I have a full machine shop at my disposal. I could make anything I want, but would rather put these old GE heat sinks to use. I expext to have 1.2KW on 2 meters for about $400 total. Not a bad deal.

    Ed
     
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  9. AA7QQ

    AA7QQ Ham Member QRZ Page

    We mill & machine many aluminum things at the shop. I am not at all worried about lapping & all that.

    Ed
     
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  10. AA7QQ

    AA7QQ Ham Member QRZ Page

    There are no plates or heat sinks. Just the LDMOSs on the circuit boards & matched broadband.

    Ed
     
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