Re: Some basic load measurements
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There is no second harmonic from the square wave of the Si5351, only the 3rd and 5th harmonic.? Also if you look at the specs of the SA612 it's only up to nominally 500MHz. The latter is pushed way out of spec. If Philip's or whoever changes their chip die, this project is stuffed.Over 200MHz of the Si5351, the instrument's capability seems to rely entirely on the maths routines, FFT or Hilbert.Sent from my Samsung Galaxy smartphone.
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-------- Original message --------From: Warren Allgyer <allgyer@...> Date: 08/08/2019 15:00 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] Some basic load measurements Elaborating: The "measurement range" quoted by the manufacturer is the range between the displayed carrier level and the displayed noise level. That range deteriorates from 300 - 600 MHz because the lower energy second harmonic is used for those ranges. It further deteriorates for the upper ranges because the third harmonic is used there.The manufacturer does not specify accuracy in measurement and Alan Victor's mathematical observation is borne out by the variance of observed return loss measurements at values lower than -30 dB. Not only are RL measurements below -30 fairly inaccurate, they are also nearly irrelevant for the sort of work this unit was designed for. If you truly need RL measurements below -30 dB then you need to be prepared to spend more than $50.Warren AllgyerWA8TOD
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