[Elecraft] Noise from KAT500?

[W2HX]

Mike, K8CN wins the cigar!



The issue is the power supply ☹ I took some spectrum analyzer plots to 7 MHz and you can see what I saw. The set up is spectrum analyzer -> KAT500 -> Dummy Load. First picture are two "max hold" traces superimposed where the problem can be seen.

https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-AC-Power.png

The "lower" trace is what I saw with the kat500 in bypass. The "top" trace is with the kat500 inline (auto or manual).



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.



Thanks everyone for the ideas.



73 Eugene W2HX

Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos



-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of Michael Carter via Elecraft
Sent: Saturday, December 2, 2023 5:52 PM
To: Elecraft Reflector Reflector <Elecraft at mailman.qth.net>
Subject: Re: [Elecraft] Noise from KAT500?



Hi Eugene,



Are you using a switch-mode power supply to feed the KAT500?  If so, try a linear regulator supply or a battery instead.



Is your KAT500 bonded to your other station equipment and AC ground with a short, wide conductor? (not just the coax shields)



Since you're not the original constructor of the KAT500, I would check inside the case to be sure that the case sections have the powder coat removed where circuit board standoffs and case section screws are placed.



What kind of cable do you use to connect the KAT500 to your shack computer?  One should NOT use a standard VGA cable as the manual makes clear.



73,

Mike, K8CN

______________________________________________________________

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 w2hx at w2hx.com<mailto:w2hx at w2hx.com>