[Elecraft] KIO3B Audio Spec

[Bob McGraw - K4TAX]

In Knut's plot with the 1 kHz peak, the 2nd harmonic and 3rd harmonic 
are clearly visible.  In the one with the low end, I agree, no 60 Hz, 
120 Hz or 180 Hz is seen.   I measured my K3S with the radio connected 
to the computer via the USB port.  No 60 Hz, 120 Hz or 180 Hz signal 
observed.

I suspect if anyone is experiencing "hum" they best look for a ground 
loop which likely exists as there is a difference in potential between 
different pieces of equipment.

73
Bob, K4TAX

On 12/31/2015 1:15 PM, ab2tc wrote:
> Hi again,
>
> BTW, some people have been complaining about 60Hz hum in the audio. I zoomed
> in one the low end:
>
> http://ab2tc.com/k3s_usb_lows.png
>
> There is absolutely no sign of 60, 120 or 180Hz in this spectrum. I have
> also listened to the signal with good headphones and hear no trace of hum.
>
> AB2TC - Knut
>
>
> ab2tc wrote
>> >Hi,
>> >
>> >Here is the spectrum out of the USB codec with a -73dBm carrier from the
>> >XG3:
>> >
>> >http://ab2tc.com/new_k3s_usb.png
>> >
>> >The K3S setting is USB with a passband of 300 to 2400Hz. I left the LINE
>> >OUT level set to the factory setting (10), and set the recording level
>> >with the Windows mixer (Win7).
>> >
>> >AB2TC - Knut
>> ><snip>