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nanoVNA: Measuring the Frequency Response of a Filter (068d)

In this video I will be showing you how to use your nanoVNA in stand alone mode to measure the frequency response of what was *supposed to be* a 50 MHz bandpass filter that I threw together. This filter was supposed to have a 50 MHz pass frequency. I discovered that one (or more) of the unmarked components were not the value I expected them to be, so the reality of this filter is somewhat different than planned. How different? You have to watch the video to find out. Included in this video are Set up the nanoVNA for a frequency response (through) measurement Proper VNA calibration Make the measurement results more readable by changing the SCALE. See below for the time markers ... ========================== Filter Autopsy Results ... ========================== First, this was a true "throw-together" filter, built without regard to various topologies and the like. So, its response will not adhere to any given standard response. Yes, the component values were different than expected. I measured the components in place (I know, not recommended for best accuracy). This included a wire jumper (AKA: inductor) which was part of the implementation. After putting the measured and adjusted values into the LTSpice model the estimated theoretical frequency response was f1 = 27.19 MHz, f0 = 45.037 MHz, f2 = 78.29 MHz The measured frequency response was f1 = 27.1 MHz, f0 = 45.1 MHz, f2 = 76.6 MHz I still do not quite get what is happening on the upper side. 1.69 MHz dif??? Nonetheless, for a thrown together filter, it is ... 'OK.' ====================== === PROMISED LINKS === ====================== nanoVNA Official Site (so they claim) https://nanorfe.com/nanovna-v2.html nanoVNA Manual (with menu map) https://nanorfe.com/nanovna-v2-user-m... Purchase nanoVNA V2 Plus 4 at https://www.tindie.com/stores/hcxqsgr... ====================== ==== VIDEO LINKS ===== ====================== VIDEO: VNA Foundations (first video in the series)    • VNA Introductions: What is it? and Wh...   == THIS SERIES == VIDEO#1: nanoVNA: A Practical Menu Walk Through    • nanoVNA: A Practical Menu Walk Throug...   VIDEO#2: nanoVNA: Measuring the SWR of an Antenna    • nanoVNA: Measuring the SWR of an Ante...   VIDEO#3: nanoVNA: Measuring the Input Impedance of a Filter    • nanoVNA: Measuring the Input Impedanc...   ======================================= ---------------------------------- Time Markers for Your Convenience ---------------------------------- 00:05 Introductory Comments 02:00 Step 1: Planning 02:05 The Electrical Side 04:10 The Mechanical Side 05:13 Step 2: Measurement Preparations 05:16 Setting up the nanoVNA 05:22 The Frequency Settings 06:09 The Display Setup 06:20 TRACE setup 06:50 Setup TRACE 0 07:00 CHANNEL setup 07:28 FORMAT setup 07:56 MARKER Setup 08:11 Select the Markers 08:34 Connecting Things Up 09:01 Calibration 10:21 Final Preparation: Connect to the UUT 10:32 Step 3: The Measurement 10:32 Changing the SCALE 11:22 Marker Movement for Measurement 11:55 Finding the Pass Frequency, f0 12:07 MARKER SEARCH function 12:12 Select the Marker 12:37 Invoke the SEARCH function 12:56 Measurement Results 12:57 The Pass Frequency, f0 13:19 Low End Response: MARKER 1 13:39 High End Response: MARKER 3 13:59 Comparing Results with Theory 14:59 Final Comments and Toodle-Oots