[Elecraft] KX3 12kHz audio spike

[Johnny Siu]

Hello Lyle,
 
I really like your last sentence.  I can still hear somewhere around 12Khz or higher.  This hearing ability is good for Hifi audio but bad for listening to radio.  My ears are very sensitive to DSP artifacts.  This is the reason why I found the DSP board upgrade for earlier version K3 was necessary.

TNX & 73,


Johnny VR2XMC

寄件人︰ Lyle Johnson <kk7p4dsp at gmail.com>
收件人︰ elecraft <elecraft at mailman.qth.net> 
傳送日期︰ 2013年08月6日 (週二) 8:51 PM
主題︰ Re: [Elecraft] KX3 12kHz audio spike


This is most likely power supply ripple from the variable loading of the DSP, which occurs at a 12 kHz rate.

You may be able to reduce it by setting MENU:RX ISO to ON.  This increases average current in part by preventing the DSP from "sleeping" between tasks, thus smoothing out some of the power supply load.

It is always best to use headphones or external speakers that have limited response above 5 kHz with the KX3.  The radio will not pass audio information above this frequency, so the only thing wide response headphones or speakers will provide is additional noise.  This is particularly true if your ears haven't "aged" to provide some low-pass function for you :-)

73,

Lyle KK7P

> While doing some tests tonight to compare the white noise of my Icom
> IC-7000 to the white noise of the KX3, both having the AF gain turned all
> the way down, I noticed...
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