Spectrum analyzer fun

Gordon Gibby <ggibby@...>

Oh what fun!

Yesterday I built a simple capacitively coupled "probe" to be used with my (1st ever!) spectrum analyzer.   A series cap of 0.01/1kV, 4700 ohm resistor, and 100 ohm to ground, (should have used 50 but didn't have it) -- then coax cable to the spectrum analyzer.

Gives roughly 15 dB attenuation based on touching the tracking generator signal.

Allows me to actually SEE the oscillators and signals as I roam around the uBix.   Wow, the signals are TINY all around the receiver, and most of the gain must be in the audio section....

I built this for 2 reasons: primarilly so I can do this demo for our upcoming Extra Class course, and let people SEE mixers in action and oscillators and filters.   Sending in a 100kHz calibrator (harmonics every 100 kHz) shows ALL the signals heading into the 45 MHz filter --- and then poof, only 1 left afterwards!

2nd, I have a heathkit SB-102 with local oscillator problems and this will help.


Gordon Gibby KX4Z

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