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Theo Markettos October 7th 10 05:02 PM

Selective level meter
 
I'm reading the calibration section of the service manual for a spectrum
analyser, and that tells me to connect the IF output to a 'selective level
meter'. I've had a google and can find lots of (mostly antique) models, but
I can't seem to find anything that describes what one of these is.

Am I right in guessing it's essentially a narrowband AM receiver with a
power meter for the carrier? So a spectrum analyser with only one
horizontal point? Are they typically more accurate than a spectrum analyser
- or can I just use another analyser?

Thanks
Theo

dave October 7th 10 08:24 PM

Selective level meter
 
Theo Markettos wrote:
I'm reading the calibration section of the service manual for a spectrum
analyser, and that tells me to connect the IF output to a 'selective level
meter'. I've had a google and can find lots of (mostly antique) models, but
I can't seem to find anything that describes what one of these is.

Am I right in guessing it's essentially a narrowband AM receiver with a
power meter for the carrier? So a spectrum analyser with only one
horizontal point? Are they typically more accurate than a spectrum analyser
- or can I just use another analyser?

Thanks
Theo


An audio distortion analyzer has a kind of selective meter, i.e. a
voltmeter with a bandpass filter upstream.

Fred McKenzie October 8th 10 06:58 PM

Selective level meter
 
In article ,
Theo Markettos wrote:

I'm reading the calibration section of the service manual for a spectrum
analyser, and that tells me to connect the IF output to a 'selective level
meter'. I've had a google and can find lots of (mostly antique) models, but
I can't seem to find anything that describes what one of these is.

Am I right in guessing it's essentially a narrowband AM receiver with a
power meter for the carrier? So a spectrum analyser with only one
horizontal point? Are they typically more accurate than a spectrum analyser
- or can I just use another analyser?


Theo-

I expect a frequency selective voltmeter will have an accuracy in the
order of 5% (1/2 dB) or 10% (1 dB) of its full scale reading. The
spectrum analyzer probably has an accuracy measured in dB, probably
greater than 1 dB.

I might depend on another analyzer if that was the only option. Then
the question would be whether the second analyzer is less accurate than
the one you're trying to calibrate! Somewhere along the line you need a
standard to compare with.

Fred
K4DII

Theo Markettos October 13th 10 10:24 AM

Selective level meter
 
Fred McKenzie wrote:
I expect a frequency selective voltmeter will have an accuracy in the
order of 5% (1/2 dB) or 10% (1 dB) of its full scale reading. The
spectrum analyzer probably has an accuracy measured in dB, probably
greater than 1 dB.


Thanks, that's useful to know.

Theo


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