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Topic Title: Oscilloscope shows extreme variation in frequency
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Created On: 06 November 2012 06:18 AM
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 06 November 2012 06:18 AM
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ubercool

Posts: 19
Joined: 11 September 2011

Hi I am using a Hameg HMO3522 Oscilloscope. I wanted it to display a 350Mhz RF which I was giving through my Rhodes and Schwarz signal generator but the scope is showing extreme variations in frequency from 9kHz to several Mhz, even the voltage is not being displayed correctly although I performed the probe adjustments etc.

What could be the problem?
 06 November 2012 09:02 AM
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amillar

Posts: 1918
Joined: 28 May 2002

How are you measuring the frequency?

-------------------------
Andy Millar CEng MIET CMgr MCMI

http://www.linkedin.com/in/millarandy

"The aim of argument, or of discussion, should not be victory, but progress." Joseph Joubert
 12 November 2012 11:53 AM
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d80s22

Posts: 8
Joined: 08 May 2002

The frequency will be worked out from the voltage waveform (measure period using zero crossing, take inverse), so you need to fix that. At the moment the frequency measurement will be suffering from "garbage in, garbage out".

Get the RF displaying correctly as a sine wave, then apply the measurement to it.

-------------------------
Dr Robin Collings MIET
 12 November 2012 04:55 PM
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amillar

Posts: 1918
Joined: 28 May 2002

I'm also wondering if this is an aliasing issue - there were some advantages to analogue 'scopes!

-------------------------
Andy Millar CEng MIET CMgr MCMI

http://www.linkedin.com/in/millarandy

"The aim of argument, or of discussion, should not be victory, but progress." Joseph Joubert
 22 April 2013 10:44 PM
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kengreen

Posts: 400
Joined: 15 April 2013

Sounds more like an intermittent failure in the sync circuits - dodgy capacitor ? Oh yes they do !


Ken Green
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