[Elecraft] Noise from KAT500?

[Victor Rosenthal 4X6GP]

This is usually true of the linear type of wall-wart, which is the quiet 
kind! They generally are composed of just a transformer, rectifier, and 
capacitor.They are almost extinct these days, but I look for discarded 
ones for use with equipment for which it is safe to use an unregulated 
power source.
The switching types mostly are well-regulated, but of course they are 
often noisy.

73,
Victor, 4X6GP
Rehovot, Israel
formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/

On 03/12/2023 5:33, David Gilbert wrote:
> 
> 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
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