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Sunday, 18 December 2016

C-Band LNB test using 2x VMA Simple Spectrum Analyser


Inspired by John at [Click here to go to relevant thread], I tried out a setup to test if a C-Band LNB is working properly.

Being a bit lazy, I just used a Deviser S7200 field meter to power up the LNB (I could have used a regular receiver or even a plain power source for coax, which I do have - I just didn't felt like searching for it, unboxing it, etc.). Connected the LNB is a simple 1-IN, 2-OUT 2-way splitter.

One output connects to the Deviser S7200, the other, USING A DC BLOCKER, connects to the SMA device #1.

The SMA device #2 connects to a basic antenna, pointed to the C-Band LNB.

Starting two sessions of the VMA Simple Spectrum Analyser (side by site on my desktop, thanks to two 22" FullHD monitors), I obtained these results:

The spectrum is inverted (and thus shown mirrored) and the frequencies are displayed, accordingly. For this I set a negative LOF of -5150 MHz, used by my AMERICAN BIRD GCF-D11C LNB. The "-" sign indicates that the spectrum is to be inverted.

Notice that you can set the "Min. Bandwidth" for transponder recognition to values smaller than 1 MHz!

Hope this inspires new ideas!



  1. Also can be used to test either a Ku or Ka lnb using a suitable harmonic from the SMA. Very useful indeed, thaks Vitor.

    1. Hi John!

      Stay tuned as the next version will allow direct frequency input for harmonics signal generation.


      Regards, Vitor