I need to test that my project will not interfere with radios in the 27 - 72 MHz band.

I can't afford a spectrum analyser. Nor can I afford to buy all tx/rx pairs in between 27 and 72 MHz (27, 35, 47, 72...) My budget is a maximum of £100.

I was thinking of modifying a radio to have a much larger tuning range, but it would need to be sensitive to very low EMI emissions. I've found AM radios are slightly sensitive to noise but probably not enough.

Does anyone have any suggestions?

  • 2
    \$\begingroup\$ 500MHz analog spectrum analyzers start at about 3X that, which is pretty cheap... \$\endgroup\$
    – tyblu
    Jan 11, 2011 at 2:53

2 Answers 2


If my time was worth nothing, or I was doing this as my own fun project, I would design and build my own rf power meter. There are schematics available for this in AARL back-issues.

If this is for work, I would go and rent the tools.

If this isn't for work, and you don't know very much about RF, and you don't have a lot of money - go make friends with amateur ham radio people in your area and butter them up.


Well, you can't be sure about 'very low EMI emissions' with all these tricks.

Just find a mate in city with spectrum analyzer and do a proper test. Even if he would ask for money, it is not gonna be much.


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