New build uBITx with Nextion screen

Jim Reagan W0CHL has made a compact build using a Nextion display.

He used a Context Engineering (Fry’s Electronics) case. It’s a tight fit and not for the beginner. I had to “mill out” (dremel) areas for the stand offs (they are nicely recessed on the front panel).   He also chopped off (with a bandsaw) off back 1 3/4″ of the case. It’s using the 3.2″ Nextion display and has a quiet  24 volt fan to keep the finals cool.  The final size of the case is just 3 x 6 x 6 1/2″.



VU3SUA case documentation

The µBITx case from Sunil Lakhani VU3SUA  is popular with constructors based on its value for money.  However, many find it difficult to find wiring guides for this case.    It is documented at various places by VU3SUA.  Sunil Sankaranarayanan VU2MTM has downloaded all of the photos and these are collected together.

VU3SUA case construction


Tips for building into VU3SUA enclosure

Dave, N8SBE completed a build of the µBITx last night in one of Sunil’s µBITx enclosures, and he has helpful observations for others using this case.

Front panel PCB

In spite of the pictures, the main board must fit OVER the front panel PCB, so that you can mount the LCD display up close to the front panel.

Dave put vertical male pins on the ends of the front panel PCB, which meant that there was insufficient clearance.   If you want to put male pins on the front panel PCB, you should use the right-angle ones (and then the mic connector will be a tight fit against the chassis mount four-pin mic connector, but I was able to just make it work).

He ordered a Dupont kit of male pins, female sockets and housings from Amazon and a suitable crimp tool:


The crimp tool works fine, but Dave spoiled a few female sockets before I got the hang of it.

If you are crimping female sockets on the ends of the original wires that come from the Relimate sockets on the µBITx (trim them to 8 inches first, then you can use the extra for other wiring, see below), then it seems the wire gauge is about 22 gauge, but the crimp die in the centre of the tool that is marked for 22 gauge is too large and won’t crimp the wire properly. He ended up using the crimp position for the smallest wire size, and it worked fine.

It is also important to insert the female socket in the tool first (Dave found that by clicking the tool 3 clicks it closed the jaws just enough to make it easy for me guide the socket into the tool), then push the female socket in far enough so that the box that encloses the male pin is completely outside the dies on the back side of the tool.

Then lightly pressing the handles to keep everything in place, insert the stripped wire into the back of the female socket, and crimp.

The wire should be stripped only about an 1/8″ of an inch, and the insulation should be inserted into the back of the female socket such that the bare wire bundle is crimped with the smaller crimps, and the insulation is held by the larger diameter crimp at the back end of the female socket.  If you strip off to much insulation, you will either fail to get the insulation into the back crimp, or you will force wire into the female socket area, and that will interfere with the male pin when it is inserted.  If you’ve done everything correctly, tugging on the wire shouldn’t make it come out, it will seat correctly on a male pin, and you should not have to resort to soldering anything.

Soldering crimp joints is a BAD idea, not only because the clearance in the female connector bodies is very close, but the solder that wicks into the wire bundle will stiffen the wires past the crimp, and create a stress point that will eventually break the wire if subjected to vibration and movement.

Dave ended up using Dupont housings/connectors on the Audio, Digital (both 8 pin), Mic (three pin), Volume (three pin), encoder (4 pin) and speaker connectors (2 pin). 

When you cut the ubitx supplied analog and digital wire bundles to the recommended 8 inches, you end up with enough left over that you can make all the other front panel connections with using the left over wire.  You can even select the appropriate colours, as documented in the wiring instructions on the HFSignals website.

Small PCB for Encoder

Dave completely missed that there was a small PCB board included for the encoder switch.  He ended up tack-soldering the ends of the four-wire bundle coming from the front panel PCB to the actual switch pins.  It works fine.

Wiring the volume control

Dave somehow got the wiring backward on the volume control (hi end vs. low end), and was “surprised” by a VERY loud noise when he first powered it up.  If you mount the control with the soldering tabs on top so you are viewing them directly when looking down at the rig with the top off, then the correct colours from left-to-right (with the front panel closest to you) are yellow, orange, green (given the wiring colors shown in the wiring section on the HFSignals website).

Power supply wiring

The power supply wiring was an issue, due to the power on/off push-push switch.

It is NOT meant for soldering, as the tabs are practically impossible to solder to (don’t know the material, but it does NOT accept solder), and the body melts in an instant. The tabs are meant to be used with push-on tab crimp connectors (You can find suitable ones at the local auto store in the electrical section).

Dave still wanted to use the PCB board, so he ended up inserting the power switch tabs through the board, pushing the auto tab crimp connectors on, and then tack-soldering the crimp connectors to the board.Ugly, but effective.
Before Dave figured that out, though, he had partially melted and loosened one of the power switch tabs.   
The rest of the power PCB board wiring went OK.  Dave put a three pin header and connector on the end of the board going to the ubitx supply wiring.  Originally he used a right angle male header, but discovered that this interfered with the mounting bracket (and likely the board when installed) for the digital interface PCB.  The solution was to bend up the pins from the board at a 45 degree angle.  Ugly, but effective.
Check the actual wiring of the DC power plug.  The diagram supplied with the enclosure kit shows using a pin for ground that was found to have a no-connect.  The other unused pin turned out to be ground (the sleeve on the DC plug). 
Double-check your wiring in this area with a multimeter to ensure that 1) You have continuity where you expect it from power supply to the µbitx board, and 2) You haven’t inadvertently reversed anything or shorted anything out. 
Don’t forget the chassis ground to the solder tab that comes with the SO-239 socket.

Wiring up the Antenna connector

Dave used the supplied antenna 2 pin connector and wiring that was supplied with the ubitx, but it was not possible to keep it only 2 inches long in this enclosure.  It’s more like 4+ inches. You could use a short piece of RG-174, instead, to lessen any possible pickup of birdies.

Digital interfaces on rear panel

Dave hasn’t used the digital interface for the back panel or the front panel RX/TX LED.


Do you like those CEC Buttons on this build?

Breadboard uBITx

Jon Titus  KZ1G  shows off his breadboard construction  technique, which he uses while his rig is under development.  The board is mounted on a piece of plywood and usea 1/8-inch clear plastic as front and rear panels for controls and connectors. This “breadboard” technique has been used by Jon for other projects, because it lets him rearrange control locations, ensure clearances between components, jacks, heatsinks, etc.  In this way he doesn’t ruin a nice front panel when later adding an extra pushbutton or switch, etc.

After learning about the W0EB and N5IB RadI2Cino (Rad I2C ino) project he needed more room for the replacement board and a larger LCD. A section of plywood was glued on the front (see photo) and the front panel  was then able to be moved forward by about 4 cm.   Jon quickly added an extra pushbutton, and drilled holes to mount the LCD.

However, when do you make the call to put the whole thing in a proper metal case Jon?


uBITx in an aluminium briefcase

Aarne Haas WY7ATH has just finished a µBitX build in an old ‘toy’ briefcase.  It makes for a good enclosure – along the lines of µBITx builds in P cases. There is a small manually switched fan inside blowing on the final heatsinks when operating digital modes.  Nice one!

uBITx panels for EF01 Excellway case

Bought the Banggood case?   Want some 3D printed drop in front and back panels so you don’t need to cut out the hole for the display and controls?

Gary AG5TX says:

“I bet some find it hard to stomach buying $27 plastic panels for a $10 plastic case when debating a few bucks differences in micro-controllers.
That said, my building brother, I too get anxious on cutting holes.  We don’t know what tools you have, and given the question, assume not a mill or a drill press.

“What I would do is cover the front side of the plastic panel with blue 3M painters tape. Scribe the centerline for the holes directly on the ‘inside the box’ portion of the plastic where it won’t be seen. I use center drills to start the holes (they are cheap), if you don’t have center drills, use a small drill bit.  Once the initial undersized holes are cut, flip the piece over and drill from the ‘outside the box’ side so if you get a chip out it won’t be seen. Best to start small and step up to one drill bit less than size. When drilling, secure the plastic panel over a scrap piece of softwood, and make this a “pine board project.”  With thin plastic and drilling with hand tools, I find that the final drill bit size is best done by hand. I have an old pcb hand nibbler tool ($10?)  for cutting somewhat square holes with patience.    Just slightly undercut the rectangle for the LCD with the nibbler, remove the tape and finish out with a bastard file and sand paper.  If all goes wrong, you can still try 2 more cases or spend the $27.  Also search this forum for good ideas on printing a full face ‘label’ which might cover up the sins of a nonperfect cut. Stain grade or paint grade? My wood working Grandfather taught me very early in life that a coat of paint covers a multitude of sins. Nothing ventured, nothing learned. Maybe someone else has some tips.”

Michael VE3WMB comments:

“I have now used three of the Excelway EF01 cases for rigs with 16 X 2 displays with good success.   The ABS enclosure panels are quite easy to work with.

“Just to add a couple of comments to Gary’s suggestions. I have found that drilling corner holes and using a coping saw to cut out the “window” for the display works quite well. As Gary suggests you want to make it undersized by a couple of millimetres.   With patience and a nibbler or even an exacto knife and a file you can make a decent looking opening. In all three cases I made
the “window” just large enough to friction fit the display without resorting to using screws to hold it in place and this works fine.

“One other point; I suggest that you mark the position of where you are going to drill holes and then make a small divot (a nail and hammer works fine for this) so that the drill doesn’t wander. Also starting with a small sized drill bit first helps. For larger holes (i.e. for BNC etc) I swear by a stepped drill bit to get the hole  to the proper size.

“The key to getting a good result is to plan and carefully mark everything in advance on the back of the panels and then take your time. Remember if an opening is too small you can enlarge it, if it is too big there is not a lot you can do so, measure twice and cut once.”

MVS Sarma says, “For cutting rectangular windows in plastic, I resort to a lamination cutter sold in India at just fraction of a $. I keep the tool drawing across the 4 lines of the rectangle (the lcd mounting window in this case on the µBITx).  After a while you can push out the small window from the plastic.

This is what a laminate cutter looks like.


Labelling the front panel (updated)

Making nice labels for the front panel of the µBITx may not be all that intuitive.  Many of us use a label writer (e.g. Brother or Dymo device).  The best options (depending on your front panel colour) may be to use “black on transparent” or “white on transparent” tapes.

Vic WA4THR was looking for a way to easily label the front panel of his  BitX40 and was pointed to the use of an Avery product. It is a transparent plastic with an adhesive backing and you can print using either an inkjet or a laser printer. You then just cut the strips where you designed the label, peel the backing, and place on the panel. Really easy, and the results are pretty good. One sheet can produce a ton of labels, too. The product is Avery 4397.

John WA2FZW uses the same product, but makes one big decal for the entire panel. That way you don’t see the edges of the individual labels. There is a full description of the process used in the documentation for his Magnetic Loop antenna controller.

Dave G4UF has another method that he uses. You don’t have to be as careful with the LCD cutting 🙂

And then Dan, W2DLC told us that he printed his out on with an inkjet printer on regular photo paper and then put some clear tape over it to preserve it with a pretty amazing result:

AA9GG adheres his printout to the case using a sheet of 3M adhesive. Basically, it’s a large sheet of double sided tape.

Daniel W2DLC uses “Loktite” spray adhesive.


Another nice build: N8GGI’s uBITx

This is a rather nice µBITx build from Dennis N8GGI.

Dennis says, “Finished wiring up the UBITX today and downloaded the KD8CEC firmware. I took my time with the case. Old retired industrial designers still like to design (and build).

“I added a keyer circuit which has a speed pot…I don’t like to run through menus to match someone’s speed. I also added a Hi-per-Mite audio filter which really makes it a nice CW rig.

“First 40 meter CW contact was New Hampshire from my QTH on Lake Erie in north central Ohio.  Second 20 Meter CW QSO was from Portugal getting a 559 report using a tri-bander at 60 feet. I tried 20 meter SSB and worked the gulf coast of Florida with a 5×6 report. It’s a great little radio! Now I still have to tackle the TX pop and try to tame down the sidetone volume issue. I hope the 1,500 watt linear doesn’t get lonesome from lack of use.”

And what lies beneath the paint!   The “see-through” version!  Dennis says, “Kinda looks like the old ‘visible V-8’ from the ’70s.”