I ordered one, along with an attenuator and RF bridge for SWR measurements, and after the usual wait for postage my anonymous grey package arrived and it was time to give it a look and consider its usefulness. We’ve already taken a look at the $50 VNA, and this time it’s the turn of the $30 spectrum analyser, in the form of a little device that I succumbed to while browsing Banggood. It has been available from all the usual outlets for a while now either as a bare PCB or in a metal box about the size of a pack of cards.
The LTDZ spectrum analyser on the bench today covers 35 MHz to 4.4 GHz, and has a USB interface and tracking source. Greetings and forgiveness for the extension and possible-probable inaccuracies and bad english.As mildly exotic silicon has become cheaper and the ingenuity of hardware hackers has been unleashed upon it, it’s inevitable that some once-unattainably expensive instruments will appear as cheap modules from China. This contributes to the low refresh rate, which also prevents an AM signal from being displayed correctly and as an extreme case a telegraphic signal.Īs a summary of the above, to say that the signal of an RF generator without modulation is looked and measured "good" but "practical" signals (the carriers alone do not serve much in real life) look bad. This makes signals with a significant frequency modulation look very bad on the screen. Properly choosing the span this inconvenience is soslayable. Recognized, the signal must fall exactly on any of the sampled frequencies because otherwise it is strongly or completely attenuated.
The third problem I have appreciated is that to be Of the two peaks, the "real" is the higher frequency (the one on the right). In a "real" spectrum analyzer this image frequency is separated at several GHz and is rejected by the input LPF. Secondly, below 1MHz of span two peaks appear instead of one, as the image frequency also appears separated twice the value of the IF (i.e. Known that offset, is not a major problem. I assume that it is because the nanoVNA accepts as 0dB the value applied in its CH1 in the calibration, which is that provided by CH0 and has those values (in the measurement frequency). The second thing I am going to say is that I have been trying to check the operation of the CH1 input as a spectrum analyzer and I have been able see under what circumstances it is more or less usable.įirst, the level measurements appear to be around 15 dB higher than the signal applied below 300 MHz and around 20 dB higher to over this frequency. I received my nanoVNA a couple of weeks ago and I have been doing many tests with it.įirst I must say my unit came without shields and I added them, but there was no considerable improvement in the base noise level. Hello again Eric and other possible readers.
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