[Elecraft] RE: Spectrogran plot interpetation

[DAVE HEALY]

Hi Jim!

Here's a shot of Spectrogram with a smaller 60Hz spike:

http://home.internetcds.com/~barbados/spectrogram3.jpg

On all the shots the K2 was on a Gel-cell.

You know what dropped the hum?

Unplugging my floor heater!  It is a little 1500W job using Nichrome =
wire and a small fan.  It is on a seperate breaker than the computer on =
the otherside of the room.  Must be the fan as the heating element is a =
closed loop, yes?

Anyway, I am learning bunches and I always look forward to reading your =
posts Jim, as I can see you are the resident audio expert.

73,  -dave- N7DKK, Medford, Oregon



On Sat, 3 Jan 2004 09:18:06 -0500, Dan Barker wrote:

>Is it 60 Hz hum?=20

I suspect that the larger one is, and that the smaller one just to the
right of it is either 120 Hz or 180 Hz.

>Why is it even there?

It is quite common for there to be hum on the interface to a sound
card. Some causes are a pin 1 problem in the sound card, or IR drop on
the shield a difference in the ground potential between the computer
and the ham rig.

For purposes of tuning your radio, you can ignore it.

Jim K9YC

Jim Brown
Audio Systems Group, Inc.
Chicago
http://www.audiosystemsgroup.com

On Sat, 3 Jan 2004 09:18:06 -0500, Dan Barker wrote:

>Is it 60 Hz hum?=20

I suspect that the larger one is, and that the smaller one just to the
right of it is either 120 Hz or 180 Hz.

>Why is it even there?

It is quite common for there to be hum on the interface to a sound
card. Some causes are a pin 1 problem in the sound card, or IR drop on
the shield a difference in the ground potential between the computer
and the ham rig.

For purposes of tuning your radio, you can ignore it.

Jim K9YC

Jim Brown
Audio Systems Group, Inc.
Chicago
http://www.audiosystemsgroup.com

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