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Author Topic: Backround noise  (Read 5298 times)

9H1FQ

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Backround noise
« on: June 06, 2011, 08:11:11 AM »

I am experimenting with Tayloe switching front end.
I have an FST3253 switching mixer, fed from 74ac74 divider and an SI570, with a FIN1002, controlled by an MC9SQ8QG8 and 24AA32 controller. An LT6231 op amp amplifies the whole thing.
The set works excellent, but I have noticed a 1Khz backround tone, present on alll bands and frequencies, it is static, does not change in the  frequency or level.
Any ideas how to eliminte please ! The whole project is well decoupled.
Paul
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WB5BL

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RE: Backround noise
« Reply #1 on: June 06, 2011, 06:45:29 PM »

What happens when you disconnect the antenna and terminate the input with a dummy load?

73 de Brian, WB6RQN/J79BPL
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W6RMK

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RE: Backround noise
« Reply #2 on: June 06, 2011, 08:35:43 PM »

What's digitizing the output of your detector? 
Or are you seeing the 1 kHz on the analog outputs?

What frequencies are you running at?
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9H1FQ

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RE: Backround noise
« Reply #3 on: June 07, 2011, 04:10:44 AM »

When diconnecting the LCD screen the tone stops.
The screen is too close to the SI570, and the FIN1002 !

Thanks all folks

Paul
9H1FQ
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An unknown gem of the Mediterranean sea is the Island of Malta. blessed with warm sun , all year round.
In just one day, you can see places which will make you travel in history from the Prehistoric temples throu the middle ages, the Knights of Malta, all the way to world war two. All the major civ
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