The N2PK is a serious SMD soldering exercise - over 300 components on the main PCB and over 700 solder joints. The blank 4.3 PCB was ordered from VE3IVM. All parts are from Digikey. The only additional components were the Valpey Fisher Master Oscillator and the Minicircuits transformers. The VP XO is a very difficult component to find! There is an alternative with Connor-Winfield MO, available from Digikey but I was lucky to find the Valpey Fisher part. I installed all components on one side of the PCB and then moved to the other.
The N2PK VNA is an advanced project - high part count / desnsity on both sides, some fine pitch ICs (not very easy to solder pin-by-pin) and some components in very small packages. Good soldering skills are a must as well as a good set of tools, soldering materials and soldering iron with fine SMD tips (I used Weller WESD51 with ETP / ETH tips). I worked on the board for about 2 weeks spending a couple of hours almost every evening. I could have done it much faster but I was taking my time, double-checking and making sure that there are no mistakes. Troubleshooting is difficult with SMDs and the capacitors are not marked which can cause a lot of headaches should one makes a mistake with the components. My approach was to install all components (small-to-large size order, but starting with the ICs) of the same type/value together, while working on the top side first. After the top side was completed, I did the same thing on the bottom side leaving all connectors for last. I made sure that there is only one type/value components out on the bench at a time to prevent confusion. How well I've done we will see once it is powered up.
I have also prepared custom heatsinks for the MO, DDS and ADC chips. The only thing left to do on the main PCB is the RF shielding cans for both detectors. I need to make screening boxes out of tinplate. After I am done with the power supply / power conditioning board and the wiring harness I'll be able to finally test the VNA.