Q1: Why do the tubes in test mode stop after a short time?
A1: Test mode is intended to help you get the clock going, and it uses a much simplified firmware to make the High Voltage generator run. In this simplified mode, the feedback loop to control the High Voltage generator is driven hard to make sure that the tubes light up. It's not safe to run the clock like this for long periods, otherwise the MOSFET can overheat. For this reason, the test mode HV generation is shut down after a short period. To restart the test mode, just power off and back on.
Q2: Where do I mount the LDR and switch, there is no location for them on the PCB?
A2: The switch and LDR (and the PIR if your kit supports it and you have one) are intended to be mounted on the case of the clock, not on the PCB. For this reason, you will not find a location for them on the PCB. You will need to mount them by soldering them to the header (usually marked "CONN_FRONT"), following the schematic for the "External Components".
Q3: Where do I get the code?
A3: You can find the code related to your clock on the manuals page (www.nixieclock.biz/Manuals.html
). Each section has some links at the bottom saying "Code Repository Clock" and "Code Repository Wifi", which takes you to the relevant software repository.