[Elecraft] Noise from KAT500?

[David Gilbert]

Most of them have almost no reliable voltage regulation either. They are 
typically designed for a certain load, and if they don't see that load 
the voltage is much higher than rated.  I've tested dozens of these 
things (I tend not to throw anything away) and it's fairly typical that 
a 12 volt rated wall wart power supply presents 16 to 18 volts (or 
higher) no load.  That can be death to a piece of 12 volt gear that 
doesn't draw much current.

Dave   AB7E



On 12/2/2023 8:25 PM, Jim Brown wrote:
>
> 99.9% of stuff that plugs into the wall has a Switch-mode power 
> supply, most of which are varying degrees of noisy. They were mandated 
> to save energy about 20 years ago, but thanks to small government, the 
> FCC has no money to enforce their Rules that they be quiet. So they 
> aren't.
>
> A typical home has several dozen of them, either in the form of wall 
> warts and line lumps or built into equipment and appliances. Rather 
> than buying bigger and better anything for our station, our time and 
> money is far better spent identifying and replacing as many as 
> possible of these nasty noise sources.
>
> There's a tutorial on my website, k9yc.com/publish.htm  about how to 
> find and replace them. All of the 12V gear in my shack runs on two big 
> batteries that are float charged by re-purposed Thinkpad power 
> supplies using Genasun charge regulators. A 100Ah LiFePO4 runs the 
> rigs, a 100Ah Sealed Lead Acid runs the rest of the stuff.
>
> 73, Jim K9YC