[RFI] Base Power Company

[K9MA]

A spectrum analyzer or a tranceiver with a spectrum display can allow 
you to see interference you might not hear on a receiver without a lot 
of tuning around. Most RFI is composed of one or more discrete 
frequencies, but they may be very unstable.  The one that was at 13.950 
when you listened on 14.050 might drift into the band at some time.

I'm not sure any receiver or SA is likely to hear "band noise" with a 
very small, untuned antenna. A good test would be to see if it can hear 
any of the weaker signals you can hear with a larger antenna.

73,
Scott K9MA


On 7/8/2025 6:52 PM, Richard Karlquist wrote:
> For antenna measurements with a spectrum analyzer, if you have a fairly
> efficient receiving antenna, the preamp will typically overload, and in
> addition you may have to add attenuation.  I suspect that anything
> described as "tiny" does not have a high dynamic range preamp.  If you
> connect a short whip as an antenna, the noise from the preamp will
> dominate and you not be able to hear over the air noise.  Any ham type
> radio receiver will run circles around a spectrum analyzer for the
> purpose of this test.  We all own one or more of those; why not use
> them?  An SA is simply the wrong tool.


-- 
Scott  K9MA

k9ma at sdellington.us