[Elecraft] LDMOS for QRO [OT]

[David Cutter]

Thanks for showing us that, Gerry, be nice to see more of the water works.  Do you have any pics of the build?

David
G3UNA
  ----- Original Message ----- 
  From: Gerry Hull 
  To: David Cutter 
  Cc: Reflector Elecraft 
  Sent: Tuesday, December 16, 2014 3:19 AM
  Subject: Re: [Elecraft] LDMOS for QRO [OT]


  Here's a 144MHz 1.5Kw water-cooled LDMOS amplifier putting out full power in a June VHF contest, with me operating at W2SZ/1.
  It was a cloudy day, and the amp was so cool, in fact, we were worried about condensation.  Look at the size!  The power supply is a 50v/50a surplus PC supply off of ebay.
  The amp was built by Brian Justin, WA1ZMS.  


  I have found cold plates on the surplus market.   Every once in a while, Electronic Surplus Sales in Manchester, NH has em.


  Amp in Action:


  https://www.youtube.com/watch?v=vegBv6ddAUA



  73


  Gerry Hull, W1VE   | Hancock, NH USA 



  On Sun, Dec 14, 2014 at 6:32 PM, David Cutter <d.cutter at ntlworld.com> wrote:
    I'm a little surprised that folks in this group haven't suggested liquid cooling for this modest application.  Semiconductor cold plates have been around for a long time, are economical to use and in my view a much better solution than forced air cooling.  They are compact, quiet, require far less cabinet space, keep junctions cooler and more stable than air could ever and enable higher reliability.

    Look at Aavid for instance, whose devices I used on many occasions:
    http://www.aavid.com/sites/default/files/products/liquid/pdf/liquid-cold-plate-datasheet-hicontact.pdf

    If you play your cards right, you can cool the amplifier and the power supply on a short 4-pass plate.  Put the heat somewhere convenient, not in your shack.

    73

    David
    G3UNA