This instructional video details the configuration and operational workflow of the Sys Joint SV4401A handheld vector network analyzer (VNA) for tuning a K&L mobile band-reject duplexer operating in the lower 300 MHz range (specifically 314.75 MHz low-side and 350.75 MHz high-side frequencies). The procedure covers setting an analytical frequency span of 275 MHz to 400 MHz, executing a complete Open-Short-Load-Through (OSLT) calibration at the test cable ends, configuring trace selections (Log Mag S11 for return loss/SWR and S21 for insertion loss/notch depth), optimizing mechanical cavity tuning slugs, and refining measurement accuracy via intermediate frequency (IF) bandwidth reduction and trace averaging.
Key Highlights & Timestamps
0:00 Duplexer & Frequency Scope: Targets a K&L mobile band-reject duplexer operating at a low-side frequency of 314.75 MHz and a high-side frequency of 350.75 MHz, utilizing a VNA frequency span configured from 275 MHz to 400 MHz.
1:09 OSLT Calibration: Executes an Open-Short-Load-Through calibration at the end of the port 1 SMA cable using a barrel connector, open standard, short standard, 50-ohm terminator, and a port-two through connection, saving the profile to slot 5.
3:53 Trace Configuration: Retains only two active traces—Log Mag S11 for return loss and S21 for insertion loss (notch depth)—while disabling the S11 phase trace and S11 Smith chart.
4:38 Port Hookup & Termination: Connects VNA port 1 to the duplexer antenna port and port two to the high-side port, terminating the unused port with a 50-ohm load.
6:31 Vertical Scale Adjustment: Modifies the S21 vertical scale from 10 dB per division to 15 dB per division to fully visualize the bottom of the deep notch filters on screen.
7:05 Mechanical Cavity Tuning: Physically adjusts the cavity tuning screws to align multiple resonance notches with marker 1 positioned at the target frequency of 314.75 MHz.
9:16 IF Bandwidth Reduction: Decreases the VNA intermediate frequency (IF) bandwidth from 6.25 kHz to 1 kHz to suppress the instrument noise floor and improve measurement consistency below -80 dB.
11:11 High-Side SWR Analysis: Places marker 2 at the high-side frequency of 350.75 MHz, recording an S11 log magnitude of -22.15 dB and a corresponding SWR of 1.17:1.
12:24 Trace Averaging Implementation: Enables a running average of 10 acquisitions to stabilize trace variation when measuring insertion loss deep within the noise floor.