PiHPSDR built with Hammond extruded enclosure
Mike Lewis
I received the Hammond extruded box yesterday and assembled it last night. I had a few mounting and encoder holes slightly off but was able to fix them and hide any evidence. The LCD cutout is also slightly off exact center. I did not have calipers at design time, just an old worn ruler. Despite measuring a thousand times, I still got some errors. I remeasured the box after it was milled with digital calipers and the errors are obvious. Should have splurged for some at design time. I have updated the front panel drawing (V1.3) as I went so in theory the latest drawing should just work. The back panel seems fine at V1.1. They are both set to 2.5mm thickness. The box is 2.5 thick, the back panel is 2.3mm. At 2.5mm Front Panel Express allows a 45 degree bevel. This box is a 60degree which is nice, but 45 would be better. Using the $40 Hammond box vs. the Schaeffer box from FPE is about $100 less overall and is taller, longer and deeper at 66mm. Not perfect but good enough. You can save another $63 by hand drilling the back panel as you need. I will hand drill the end panels as needed. That will be easy since I am not making large square holes for the RPI.
I used Dayton 30mm open frame speakers on the back panel which was milled for those speakers, vent slots and a 40mm fan. A short audio test with the end panels slipped on shows they are usable, not great. It could change once I finish installing the rest of the parts inside. I used a pair of $8.00 1.25” square enclosed speakers on the SmartiPI Pro case version and they actually sound good. The enclosed plastic case helps add a lot of bass response and filters out some high freq noise. I install a speaker select switch and external speaker jack on these controllers for better sound options. The USB dongle drives the amp and is also the mic input.
I will add a mezzanine board to mount a SSD salvaged from a laptop, a 12V 3W stereo amp module, USB dongle(s) and maybe a USB hub inside. This box is an inch longer than the PCB and I decided to shift the PCB to the far right making room on the left for a Mic and phones jack and had just enough room for right angle USB and Ethernet connections on the RPi so that I can hide most all internal cabling and bring out only what I need on the back or an end panel. I could also move the RPi to the mezzanine board and use a 40 conductor ribbon IO cable giving more freedom to place things, direct connect USB audio dongle(s), keyboard or headset dongles, without need for USB extension cables. I have a RPi Zero hat 4 port hub board with Serial to USB converter that could be used, TBD for serial connection to external computer. More likely the hamlib TCP connection will be used but depends on the SDR app using on this controller at any point in time. I am keeping the HL2 and OXCO separate, located nearest the antennas and amps elsewhere in the house or outside, or in the back of the VHF rover truck.
I tried a cheap Boefang speaker mic and it works but not great. I normally use a Elecraft MH2 mic and that works very well. Mic button is used for PTT (MOX).
I will be looking for a tilt bail solution. The sound improves a bit when it is tipped back also.
The encoder I used is a tad short and the only knob I had that would fit was an Elecraft KX2 aftermarket solid aluminum knob with spinner dimple. It works fine, but I will be looking for a larger weighted knob. If I was to build another one I would look for an encoder with a longer shaft or mount it to the front panel.
The PCB bows a bit in the middle causing the lower row of buttons and encoders to not extend to the proper height. This makes it hard to fit my aluminum concentric knobs. I am thinking a 10” long piece of aluminum angle stock behind the board mounted to the 2 lower corner PCB mounting screws will fix that.
The headphone jack I used required me to nibble out a couple mm of the PCB for clearance.
Mike
K7MDL EL87sm & CN88sf
