What's interesting is that all of 60 Hum and it's harmonics are gone.
The line out is 2.
I have the Mike volume:
Balance is all the way over to one channel.
Volume in full
I adjusted line out to flat top and halved it.
The JT65/JT9 display looks good now.
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Thanks Jim & Rick for your help.
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On 5/18/2014 12:42 PM, Larry Lopez wrote:
So I set the balance control to kill the "chaff".
I then raise the volume in the K3 line out until it flat tops
and I back it off by 2.
Good method, BUT -- better to drop the level by half the voltage from
the "flat top" point. That's because the disto
The gain of the sound card (the volume) can be changed by the driver so even
if the K3 output doesn't change, the levels can still change.
I leave the software (driver) maxed out and the K3 Lin Out at 1 (almost off),
but this risks swamping the card AGC so I use the K3 filters to limit what th
So I decide to give up and set the audio level right.
So I get the free for private use sound card oscilloscope
http://www.zeitnitz.de/Christian/scope_en.
I picked this one because it was first when I goggled "sound card
oscilloscope".
Very nice.
But gee, there are 2 channels for the mike and a
I switched to a Creative Sound Blaster X-Fi Go!
USB dongle and that got rid of the hum from
the laptop charger.
I got this originally because the desktop
I use has no sound support at all.
It was an extremely cheap server box
that runs Linux.
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I was wildly optimistic in this.
A second source of "hum" is the switching supply
of the laptop.
It's similar to the power supply hum.
Even though it's clearly a switching supply.
Curiosly the laptop need 12 volts.
So perhaps I can pick that off of the linear
power supply.
Or maybe run everythin
This is actually covered already but I need to mention it.
When the WSJTX waterfall started losing signals into the noise
I noticed that there was a neat periodic set of signals that
lined up with the frequency ticks. Eventually it dawned on me
that they were 120 Hz apart and eventually I found a
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