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Categories | Power Supplies | Pyramid PS-9KS Help

Show all reviews of the Pyramid PS-9KS

You can write your own review of the Pyramid PS-9KS.

WB4QWA  Rating: 2/5 Jan 27, 2014 01:03  Send this review to a friend!
Marginally Usable - Don't Believe The Specs  Time owned: 0 to 3 months
Let me start with the good things...

I wanted something that took up a small amount of desk space and was quiet (fanless) to power a CB or a 2-meter unit at low power. It does that as long as I keep transmit power down to 10 watts.

The ripple at idle is only 2 to 4 millivolts depending on which oscilloscope I use. I did not check ripple under load.

For those who open up such things, the capacitors dissipate within two minutes.

The inside gives easy access to components, and the schematic is available.


Now the darker side...

The power rating should be more like 4Amps rather than the claimed 5A. At 4A, the voltage has dropped to 13.2, and the voltage goes downhill quickly from there. It looks like a puny transformer that just can't deliver.

Looking around the board, I found one bad solder spot where the solder only covered half of a wire lead.

In the rectification section, rather than use single diodes of a proper amp rating, they used weaker diodes coupled in parallel pairs. This is a design that can lead to trouble later as components age, so I replaced them with Schottky 8A diodes and added heat sinks for good measure.

Checking the voltage across the smoothing capacitors, I measured 25V. Looking at the maximum voltage rating printed on the caps, I saw 25V. Cutting things close, eh? I thought of doing a preventive replacement, but since I have another power supply available, I decided to just see how long they lasted as a matter of curiosity.

It claims to have short-circuit protection, but I don't have knowledge of what a proper circuit for that should look like. If someone else has a chance to look at that aspect, I would be interested in your opinion.

While the plug-in adapter is a nice feature, its negative ring extends somewhat beyond the faceplate and sits less than a centimeter from the positive post connector. This means that if you are using the positive post, you need to be very, very careful as to how your positive connection is bent or insulated lest it bump into the negative. It looks like an accident waiting to happen.

So I would conclude that the company is run by accountants rather than engineers. 
Product is in production.
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