Re: 30 meter noise


Steve W3HF
 

Steve,
I tried a lower res mode, but it only reduced the noise slightly.
Think a higher res might help? What's the Sys Tray thing you
mentioned?

Jay - AA8QQ
Any change in mode should help. Assuming the noise you see is
similar to mine, it's some multiple of either the line rate. So it's a
combination of your (vertical) resolution and your refresh rate.

Let's see, if you have a refresh rate of 72 Hz (that's 72 video frames
per second) and a video mode that has 1024 lines, that's 72x1024
lines per second, or 73.728 kHz. Depending on the design of your
video card, there are probably harmonics out the wazoo.

But if you were to switch to an 800 line mode, the line rate is 57.6
kHz. And if you went to a 1280 line mode, it would be 92.160 kHz.
The trick is to find one that's clean at the frequency you want to use.

The system tray utility is something that may or may not be needed
depending on your version of Windows. Earlier versions (some
Win95, for example) required you to reboot whenever you switched
modes. There was a utility that came with the Windows Power Toys
set called QuickRes that let you pop up a utility that did the switch on
the fly. Once that came out, many video board manufacturers added
it to their own utilities, so it may not be needed for you.

Steve

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