[Elecraft] K3S Audio buzz on transmit, especially AM

[donovanf at starpower.net]

I had this same problem years ago before purchasing my first K3. 
It turned out to magnetic field coupling between my HyGain 
T2X control box and an audio transformer in the transceiver. 


As Don suggested, be sure all power supplies including computers, 
UPSs and lamps are turned off during the test. 


If this doesn't work, take to K3S to a friends QTH and repeat the test 


73 
Frank 
W3LPL 

----- Original Message -----

From: "Don Wilhelm" <donwilh at embarqmail.com> 
To: elecraft at mailman.qth.net 
Sent: Friday, April 26, 2019 9:51:15 PM 
Subject: Re: [Elecraft] K3S Audio buzz on transmit, especially AM 

In addition to operating from a battery isolated from the solar system, 
I would recommend that you do a quick test - remove all cables from the 
K3S except the power cable and a coax to a dummy load. Power down all 
power supplies in your station, including any desk lamps. 
Go into Transmit by tapping the XMIT button. 
Is the hum still present? If not, then start connecting things to your 
K3S one at a time, doing the same test after each thing connected. 

Of course, if the hum is present with nothing connected, contact 
support at elecraft.com - but I cannot imagine a hum with harmonics of 60 
Hz being induced if you take away all the 60 Hz operated sources in the 
area. 

73, 
Don W3FPR 

On 4/26/2019 5:36 PM, K8TE wrote: 
> The word that struck my attention is "solar" and the possibility of that 
> controller causing noise. When you were connected to just the battery and 
> dummy load, was the battery disconnected from the solar system? And, at 
> what level was the buzz relative to a full power carrier? 
> 
> Every transmitter has some noise on its signal. Specifications and FCC 
> rules in some cases call for a specific ratio. I can't imagine a factory 
> reset solving a problem like this. Be certain you have saved your 
> configuration first. Solving issues like this is not magic, but sometimes a 
> mystery. 
> 
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