I have decided to build up another NS3 module to try out some different output transformers and would like to relate some construction tips based on what I notice as I build this one up. I hope this information is found helpful. I plan to build on this page as I get feedback from others.  I will give contribution credit for any received tips that I add to this list.

Mechanical Layout

• I do the mechanical layout and chassis work first before the mounting of any parts on the PC board as shown here: Chassis Preparation. I use the blank PC board as a template for marking holes for drilling the chassis. If your plan is to mount the PC board with #2 machine screw standoff hardware then the board corners should be drilled first. The positioning of these holes is critical. Using my drill press I first drill a 1/16" pilot hole followed by 5/64" and then the final 3/32" hole which is slightly oversized for #2 hardware. Using a square needle file I then file notches in the connector board edge to mate with the coaxial connectors. The notch depths should be filed up to the edge of the center conductor connection pads to fully remove the narrow ground strip along the board edge. Otherwise the centre conductor may become shorted to ground when soldered as the filing disrupts the solder mask protection. A photo of a board I prepared for a diecast aluminum box can be seen here: PCB Prepared for MountingPCB Mounting.

SMB Connector Mounting

• The three SMB connectors used for the DataIN, DataOut and RF_In are too close together for the connector flange hex ridges to clear. This spacing was predefined and dictated by the surplus enclosure design. This may not be an issue if you plan to use an alternative enclosure as the data lines, which are not particularly critical, can be wired out to an alternative connector mounted away from the RF coaxial connectors. If using the same layout as dictated by the surplus enclosures install the two outside connectors first and then use a #8 split type lock washer as a spacer for the center connector. This will allow the flange nut ridges to clear. You will need to spread the lock washer open a little to clear the #10 SMB connector threads. Refer to these photos: SMB Connector Mounting Photo Gallery

Parts Placement Reference

• For parts placement reference make a color print out of the parts placement pictorial at:  NimbleSig III PCB Parts Layout Pictorial    . It is relatively easy to read this blowup pictorial compared to the PC board silkscreen and there will be less chance of an error if you use them both.
• Note that the IC pin "ones" are identified with a black dot not to be confused with the vias which are purple on the pictorial.    
• It is quite easy to orient the RF detector chip and EEPROM the wrong way. Viewing the board with the silkscreen text the right way up the pin ones for these two chips are at the bottom right corners.

New SMD Parts - Installation Sequence
    With the experience of building up a half dozen or more of NS3 modules under my belt I have settled on the sequence described below. Note that I use conventional soldering techniques with a very fine tipped temperature controlled iron along with very fine (0.015") solder. I use a good quality 7X dissecting type stereo microscope along with good flouresant daylight temperature lighting. This information will be of limited value to those set up for more advanced techiques. The sequence that works best for me is as follows:

1. build the low pass filters up with the tiny 0402 components
2. build and test the power supply sections. (Note: If you are soldering by hand it is easier to install the relatively low profile power regulator chips, resistors and ferrite beads that are located close to tantalum capacitors prior to soldering in the higher profile tantalums. Otherwise the tantalums tend to get in the way of the tweezers. Similarly do not install the JTAG connector until after all the small passive components have been installed.)
3. install the remaining passive components, re-check the power supply busses
4. install the EEPROM and AD8307, re-check the power supply busses
5. install the MPU, complete continuity tests for adjacent pin shorts and re-check the power supply busses
6. the last and probably most critical step is to install the AD9958. I have written a more detailed procedure for this step which can be found here:   NS3_AD9958_ChipInstallProcedure

SMD Parts Management

• Considering most of the SMD components cannot be identified as they are not marked and many have values that cannot be readily measured parts organization and placement management is critically important. If the parts get mixed up it is a nightmare.
• As shown in the linked photo I use labelled pill dispenser organizers for the components. These two pill cases can hold up to 56 unique values. I don't bother keeping the common 0.1uF bypass capacitors here as I buy them in 100 lots and just leave them on a long tape which is well marked.
• When I receive the parts shipment I mark the back side of each tape with the value with either a pen as shown here or by using my trusty scissors I cut the value out of the spare label provided with the part and stick it on to the back of the short section of tape.
• When I am installing parts I only take out one value at a time and place them into a staging area for pickup. I found the inside of the  lid for the Bud enclosure with a small sheet of plain, white paper placed within the ridged perimeter works nicely for me. Once I am done with one value I put any remaining back into the appropriately labelled pill organizer compartment and then (and only then) move on to the next value.
  

Low Pass Filters

• The inside rows of 0402 components consisting of the parallel resonant circuits should be installed first as shown here. Then the bypass capacitors can be installed from the outside edges last. 
• I install these components by tinning one of the pads first whilst leaving the secon bare. Then while viewing with magnification the 0402 component can be slid into place with the tweezers in the left hand whilst the solder is reheated with the iron in the right hand (or visa versa). Notice the center pads have be pre-tinned with solder in preparation of the installation of the bypass capaciotors as shown here.

JTAG SIP Connector

• The JTAG SIP connector should be the last component installed on the board as it is relatively high profile and tends to get in the way.
• I suggest this component be soldered in manually even if a soldering oven is used for the rest of the board.
  
• Prior to soldering I cut the pins off flush to the bottom of the board as shown in the sip connector install photos.

MPU Idle Loop Execution Pin Voltage Reference

• For troubleshooting reference the MPU pin voltages measured while NS3 was running within the idle loop are available via this link.