[Elecraft] Noise from KAT500?

[Dave (NK7Z)]

Bill,

At the risk of going a bit off topic from Elecraft here--  I use a power 
distribution block, and run 12 volts to every device I can reach from a 
known good supply.

For the items I can get to with that 12V I go to the local thrift 
stores, and look at the used wall wart power supplies.  I buy the heavy 
ones...

I then test them at home, both loaded and unloaded for voltage and RFI. 
If good I use them, if bad, I recycle them.  Most used PS at the thrift 
stores are cheap, and the heavy ones are usually transformer based, and 
RF quiet..

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 12/2/23 21:19, Bill Johnson wrote:
> It gets worse with all the new gadgets and LED lighting.  I just installed new plant lights, LEDs, and the racket from the wall warts is terrible.  I shut them off when operating, or not interested in lighting up the plants.  Terrible view of the noise on K4 graphic display.
> 
> Bill
> K9YEQ
> 
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of Jim Brown
> Sent: Saturday, December 2, 2023 8:25 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] Noise from KAT500?
> 
> On 12/2/2023 5:48 PM, W2HX wrote:
>> I then replaced the wall-wart power supply with a 12V battery. And
>> this is what I saw for BOTH bypass and inline. Clearly the problem.
>>
>> https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-battery.png
>>
>> using a battery, the noise is about -80 dBm. Using the wall-wart, in
>> some cases the noise is as high as -60 dBm
>>
>>
>>
>> My task now is to either leave it on battery or preferably, find a low noise PS.
> 
> 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
> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html Message delivered to k9yeq at live.com
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to dave at nk7z.net