M0WWA_VNA_assembly

VNA Assembling


The bare dual detector v4.3 main board.	Surface mount adhesive heat curable is applied for holding ICs in place during soldering operation.	Chips are gently placed.
Board ready "to cook".	Board goes to the oven to cure the adhesive	The computer controlled oven is progammed for cure operation.
After bake the board is cleaned. Board is cleaning several times along the assembly.	Solder paste is applied.	Remaining oven solderable SMD components are placed on board.
The board goes back to the oven. It is progammed for reflow soldering.	Next, components on top side, connectors, transformers and master oscillator are soldered at hand.	Finished bottom side
Screen walls among detectors and DDS sections. DDS ICs and Valpey Fisher master oscillator cover with two layer heatsink. Current version uses Connor- Winfield master oscillator)	Finished top side. Board are ready to first test.	Multiple tests are conducted along the wiring stage. Once the VNA is totally assembled and boxed, it is burned for 24 hours.

	Measurement bridge assembly details


The measurement impedance bridge is mounted on a 110x36x30mm (4.331x1.417x1.181in) 0.5mm tin plate enclosure, providing more efficiency Faraday screening to electric and magnetic fields that aluminium ones. After punch both halves are soldered with Ag/Cu/Sn alloy, resulting a sturdy assembly.	A thin copper sheet is placed between BNC connectors and box walls to seal any RF leakage. The excess of copper is cut after fixing connectors. To improve ground connectivity Brass Machine Phillips Pan Head Screws are used.	Copper Beryllium alloy crinkle washers and brass nuts fix the connectors.


The bridge PCB ground plane are soldered to box walls using Ag/Cu/Sn alloy. Transformer is original Mini-Circuits. Bridge resistors are precision 0.1% Connectors match with customer preferences.