Author Topic: G8FEK BBGen+ 6GHz noise source  (Read 1837 times)

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Offline nctnico

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G8FEK BBGen+ 6GHz noise source
« on: September 07, 2016, 08:35:28 pm »
I recently bought a BBGen+ 6GHz noise source from http://www.g8fek.com/BBGen+.htm because I wanted to try and see how useful it would be.

I played a little bit with it and it turns out the output level is quite low. According to the specs -77dBm/MHz at 443MHz. I tested it by averaging the noise floor of my spectrum analyser and then averaging the output from the noise source. At the higher frequencies the difference between the two is less than 5dB so it does not seem very usefull at higher frequencies. Ofcourse when using a narrower RBW both traces drop by the same amount. On my scope (1GHz bandwidth) I measure an output of 3.3mV RMS (around -35dBm) with peak-detect on. All in all I think it needs an extra amplifier (especially for the higher frequencies) before it is really useful.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Offline g8fek

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Re: G8FEK BBGen+ 6GHz noise source
« Reply #1 on: April 26, 2017, 09:45:54 am »
Noticed the spectrum analyser has 10dB of input attenuation selected.

Select 0dB input attenuation on your SA and the BBGen+ will demonstrate 10dB more noise above the instrument floor than seen on this plot.

If you have a spectrum analyser with internal preamplifier then expect typically a further 20dB more noise above the instrument floor (30dB total increase on this plot).

Hope that helps.
 
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