nanoVNA balun test harness by N9LR

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STD nanoVNA balun test harness by N9LR

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License: GPL 3.0

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Update time： 2022-07-09 17:18:23

Creation time： 2022-07-09 17:02:42

Description

Block diagram and schematics (not for simulation or PCB) of a hand wired test board to automate balun testing using nanoVNA. Only intended for HF range, not tested on UHF/VHF, but chances are it will work OK there as well.

Board supports:

SOL Calibration
S11 using 50 ohm
S21 in DM (differential mode)
S21 in CM (common mode)

Current implemnetation uses dual relays (had those in stock), but can be simplified with SPST

NOTE: asumtion is that nanoVNA internaly bonded grounds have no significant impact on test

Board pictures here https://photos.app.goo.gl/ceLchzVR9721NXH3A

Design Drawing

schematic diagram

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Block Diagram
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Schematic
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50 ohm S11
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DM S21
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CM S21
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SOL Calibration
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PCB

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BOM

BOM download Purchase Parts

ID	Name	Designator	Quantity
1	50 Ohm	R11	1
2	+12V 200mA	H1,H4,H5,H7,H9	5
3	SHORT for calibration	H2,H3,H6,H8,H10	5
4	2N3906(SOT-23)	Q1,Q2,Q3,Q4,Q5	5
5	50 ohm	R1,R4,R5,R7,R9	5
6	1k	R2,R3,R6,R8,R10	5
7	Port 0	RF1,RF4,RF5,RF7,RF9	5
8	Port 1	RF2,RF3,RF6,RF8,RF10	5
9	dual relay	U1,U2,U3,U4,U5,U6,U9,U10,U11,U12,U13,U14,U15,U16,U17,U18,U19,U20,U22,U23,U24,U25,U26,U27,U29,U30,U31,U32,U33,U34	30
10	SW	U7,U8,U21,U28,U35	5