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Spectrum Analyzer

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Eaglepride82:
I have an old Spectrum Analyzer (HP8591EM - EMC ANALYZER) and I would like to Measure the Amplitude and Frequency (Sound Level) of audiable noise that is present from coil whine of a common mode inductor.  Basically, is there an easy way to connect a microphone to a spectrum analyzer? Is there a simple preamp circuit than can be used with the microphone?  The purpose for these measurements are to demonstrate different dampening techniques and record sound level reductions.

bob91343:
That spectrum analyzer probably isn't suitable.  It doesn't have the required frequency resolution to analyze audio signals.

I have a similar model 8594L and its best resolution is 300 Hz and not too good there at that.

Eaglepride82:
OK. THanks.  This analyzer will scan 9kHz to 1.8GHz.  I was hoping I could put it in continuous sweep mode and scan the range from 15kHz to 20kHz.

TimFox:
For audio purposes, the 9 kHz lower bound on typical SAs is a nuisance.  Within the range of your unit, you could use a preamplifier after a reasonable microphone.  In my collection, I have an -hp- 465A and two PARs:  113 and 117/114.
The 465A has a fixed bandwidth (covering audio up to about 1 MHz), a high-Z single-ended input, and can drive 50 ohms.
The two PARs have high-Z differential inputs and selectable hp and lp  filters.  The 113 has a 600 ohm output (needs a pad to drive 50 ohms neatly), while the 117/114 combination can drive 50 ohms.  I don’t offhand know the modern equivalents.

daqq:
Unless there's something weird going on you should be able to pull it off with an oscilloscope + simple preamplifier.

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