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Author Topic: Power Supply size?  (Read 3710 times)
N4NYY
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Posts: 4758




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« Reply #30 on: February 18, 2013, 06:43:24 PM »

If you need a small footprint switcher for portable use, this is about as small as you can get for 25 amp continuous. I work at HRO on Saturdays and sell a lot of these. These are hugely popular for ecom because of their size. And it has powerpoles. The Astron 35M if perfect for a base but too big for portable use. I have that as my base PS.


http://www.powerwerx.com/power-supplies/powerwerx-30-amp-desktop-switching-power-supply-powerpoles.html


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K1CJS
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« Reply #31 on: February 19, 2013, 01:59:40 AM »

Those who say a twenty or a twenty five amp supply would be plenty aren't remembering that supplies used to their capacity get warm--sometimes very warm.  For use in an emcomm box where air circulation may well be problematic, that is asking for trouble--and one thing you do not need is a failure right in the middle of an activation.

Excess heat is the cause of most power supply failures, not electric line transients (although the cheaper switching supplies sometimes don't have sufficient protection against them) and heat is what has to be protected against.  You do this by making sure you never draw a full rated load from the supply.  Taking the maximum amperage rating 'pull' of the radios and adding twenty percent more as a cushion almost always insures that the power supply will never get so hot that it's mounting in an enclosed space will hurt it.

As I said before, Do you want to spend a LITTLE MORE NOW, or a LOT MORE LATER?
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K8GU
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« Reply #32 on: February 19, 2013, 05:06:40 AM »

Buy the biggest power supply you can afford, lift, or tolerate in your shack.
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K8AXW
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« Reply #33 on: February 19, 2013, 07:32:41 AM »

Quote
Buy the biggest power supply you can afford, lift, or tolerate in your shack.

 Grin  You're my kinda guy!  I also feel a kinship to Tim, the Toolman, Taylor of TV fame. 
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W8JX
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« Reply #34 on: February 19, 2013, 10:47:34 AM »

As I said before, Do you want to spend a LITTLE MORE NOW, or a LOT MORE LATER?

There is another way of looking at this too. A big oversized linear supply draws a lot more power when idle and under load than a modern compact switch so you can pay more now to buy that big door stop and pay even more later over its life span to feed it with its lower efficiency.
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K1CJS
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Posts: 6034




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« Reply #35 on: February 20, 2013, 07:55:26 AM »

There is another way of looking at this too. A big oversized linear supply draws a lot more power when idle and under load than a modern compact switch so you can pay more now to buy that big door stop and pay even more later over its life span to feed it with its lower efficiency.

I'm not arguing linear vs. switching, I'm arguing having a supply with extra capacity to prevent overheating and/or failure.  Please stop reading more into posts made than are there.
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