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[AMPS] Transformer ++

To: <amps@contesting.com>
Subject: [AMPS] Transformer ++
From: wc6w@juno.com (Radio WC6W)
Date: Mon, 26 Mar 2001 19:13:48 EST
On Sun, 25 Mar 2001 17:07:11 -0500 "Alex Von Yonkers"
<avy@qwestonline.com> writes:

Hi Alex,

>Ok Marv...
>
>With this all said and done it appears that a 60V/50-100A
>Transformer+Rectifiers+chocke+ 1F cap will be cheaper and more
expedient...
>However, the size and weight will kill an elephant :)

   Ahhhhhh... would an elephant even notice an extra 200 lbs?

>Thus, I believe a 2KW PS building block is more manageable and if need
arises for
>more, I can always parallel them, assuming I build in power sharing
>circuitry.:)
>
>I think the PS will be twice more expensive than the whole amp :)

   The switcher should cost less than just one of those RF FETs that you
mentioned initially.


>What do you think?

  My vote is for the 20 lb option.

>
>One more thing I have not addressed. The overshot at power on... And
also
>Thermal Management of the PS itself. IF we have ,say, 75% efficiency,
1/4 of
>the power will be delivered as heat. A substantial amount at these power
>levels :(

  That's two things.  :-)

  The initial power up will have to be somehow soft-started to protect
the mains -- so, no overshoot here.

  With just a little bit of care the SPS should run over 90% efficient. 
Of course, that still means there will be 500W to remove with a decent
sized heatsink & fan arrangement.

>But overshoot is what really waries me.

  And there shouldn't be any significant overshoot during transmit power
switching either.  Both the input stage (PFC) and output stage (Phase
controller ZVS) are regulated.   The PFC should stay within about 5% of
its nominal voltage under all conditions and the output stage should
easily hold better than that over load.

   

>Thanks to you and Jeff

  You're welcome.

73,
  Marv WC6W  





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