Biteensio strengthener

Jim Sheldon W0EB, TSW Project Coordinator, has indicated a way to secure the BITeensio to the uBITX main board when it’s plugged in.

He used a 3D printer to come up with a nice set of hold down clamps for the BITeensio.  These  mount using the front corner mounting holes on the main board and hook over the cable clearance notches on either side of the BITeensio. He has updated the TSW website ( with all the details including pictures.

Jim will sell printed brackets, but only in the US, as international shipping would be too costly.   Anybody, however, who has access to a 3D printer can print their own, nas Jim has made the printable .stl file available on the website

So if you have one of Jim’s BITeensio cards installed in your uBITX then it should also be available on “Thingiverse” shortly.

These strengtheners only take about 40 minutes to print and if you use the print resolution and parameters included in the zip file they will be quite strong and easy to install.


5″ Nextion screen files

Mark AJ6CU has added an updated version of the KD8CEC Nextion code for the 5″ screens (Basic and Enhanced) to the files sections of GROUP IO BITX20 list. (Only the 5″ Enhanced has been tested, as he doesn’t have a 5″ basic screen to test with.  This work is an extension to the “heavy lifting” already done by Joe Puma (KD2NFC).

Mark couldn’t help himself and did some “improvements” to the user interface that you may or may not like. He has included the HMI file in the directory as well, so you can adapt it how you would like it to look if you know how to edit HMI files.

If you have a 7″ or 9″ screens, you should be able t load up the HMI, set the device to match your screen and regenerate the TFT file. If you have one of these larger screens and can’t figure it out, it is suggested you contact Mark.

Files: AJ6CU Nextion 5-inch files/5inch June 10

A summary of major changes that were made to Joe’s original effort”

  1. Home page
    • Correction of scale for histogram (have more space, so let’s use it!)
    • Addition of direct access to memory STO/LOC screens (had to eliminate the Radio tower logo, sorry)
  2. Various
    • In case you had not noticed, the button to get “Home” was in various locations, although not done, I am in the process of moving it to a consistent place (upper right)
    • Scaling changes to Bandscan and Spectrum
    • Various pages required you to hit “read” or “refresh” to go get the data. I made this happen on page entry. Kept the refresh button as this seems to be a little flakey.
    • Tried to introduce a consistent color scheme. Blue background, white letters where you can change, yellow for titles.
    • All screens (except home screen) will eventually have the name of screen in upper right in red.
    • Button pushes go green when pushed and return to grey when released
    • Added a few more scrollbar slider sizes so that the slider fit the slide bar better.
  3. Frequency entry (touch the middle 3 numbers on home page) is now a little more obvious. When you are in direct frequency entry, you only see numbers, When you are in Band select, you only see the bands.
  4. Memory to VFO redesigned. Seemed easier to use for me.
  5. VFO to Memory – Mark still doesn’t like this one. He would like to make it more like Memory to VFO where you can see all 10 memory slots and then select the one you want to overwrite. For now, he has just replaced the keyboard with a standard one that pops up when you click in the name and some fancy arrows to spin the mem#.
  6. Although it is against his better judgement, he did make available KD8CEC’s debug screen. Tried to warn you off, but i am sure someone will do something awful to his/her poor ubitx using this screen. 😉
  7. CW setup screen redesign (and it automatically fetches data on startup)

There are some issues remaining … The biggest issue being that when you go into a submenu (e.g. CW setup/MemtoVFO, etc.) the Spectrum Histogram in lower left corner doesn’t always automatically restart.

If you change any control VFO/Freq, mode, etc.) it restarts.

This is going to be a pain to debug because of the extensive use of timers and state machine in the Nextion code…. Would welcome anybody that can make a suggestion here.

I have also not tested it on a Basic 5″. There may be performance issues, especially since the scale of the graphs has increased.

Mark says there is still lots of work, as he also wants to get rid of some of thebackground pictures in the control screens that really don’t match the others. The bandscan is something he would really like to “adjust” because it is really not obvious how it works. And perhaps even a “?” in upper right of some screens for a little help?  He plans to  put together another update shortly.


Add S-meter to VK3YE Audio AGC

Curt WB8YYY has been pleased with the  somewhat unusual VK3YE AGC circuit, that uses a LDR and LED pair,  as it nicely removes the top of large signals.

VK3YE has suggested measuring current in parallel with the LED that drives the AGC action, but he found this gave little indication of relative signal strength.  In fact, it works much better measuring current in series with the LED.

Curt is using a small meter movement supplied by Sunil, about 250 uV peak current.  A shunt resistor across the meter is necessary since the LED current at peak is at least 20 mA.

The approximate value of the shunt resistor can be found using the formula Rsh = ( Im x Rm ) / Ish.  Rm was unknown but Curt was able to measure it with his DVM at around 500 ohms.  Inserting the two known values gives a shunt resistance value of 6.25 ohms.

Curt found a resistor of around 5 ohms and it working nicely.

He says “Its not a real S-meter response – let’s call it a signal strength meter.”  It can discern signals from approximately S5 to S9.  for signals that do not result in meter movement, the LED itself could be observed to sense signal strength – but the meter represents a nice touch.


Running out of room in the enclosure

Olivier Grand shows off his µBITX transceiver.  He complains that he doesn’t  have enough room (even with the IRF510 out of the box) to install the JackAl Board.  He has installed:

  • an audio amp with tone control,
  • a mike compressor
  • the standalone analyser from KD8CEC
  • two 5V rails (one for TX and one for RX) and
  • a Li-Ion battery with protection bar

Olivier asks for forgiveness for the anarchic wiring because his rig is still under construction.


Sourcing boards for the WA2EBY amplifier

A number of constructors have eyed up adding an afterburner to their µBITx.  The usual cautions apply:  make sure your µBITx has clean output with earlier v3 and v4 boards having been upgraded to remove harmonics and spurs, before even considering adding a power amplifier.

There are a range of cheap Chinese and Russian kits available to give you between 40w and 70w output.  However, these may be better avoided, since you can build a WA2EBY power amplifier without a lot of effort.   This is a very solid design, and well proven.

Some list members suggested it may be hard to source boards for this amplifier design.  However, take a look at: (pointer to availability of boards) and and

Allison KB1GMX commented:

Its a good design and allows for getting good performance at higher frequencies. Mine with a little effort does 37W on 10M (1.8W drive) and with the same drive at  40M about 55W. 80 and 20 are about 50. Never though to try 15 or 17m but I’d expect about 44w.  The 1.8W is because I use an attenuator at the amp input as most of my HB radios do 4W which is excessive power or the amp.  FYI I run it at 28V.

It is a good amp.  Mine is now 13 years old and still running the same set of IRF510s. I did use a large heatsink (4×8″ with 1″ fins and the base thickness was .300″).  Some call it overkill, but with no fan running and with a brick on the key for 10 minutes, the amp doesn’t fail.

At least one of the “70W DIY AMP” I’ve seen did produce that much power for about 1 minute into a dummy load before it blew up.  Failure was likely due to self oscillation or overheating of the supplied heatsink.  The heatsink was maybe pentium II vintage with mounting points for
a fan and not at all large or having many fins.

HF Linear Amp 40 Watts Kit

MVS Sarma also points out that Sunil VU3SUA sells  a set of black masked PCBs for the WA2EBY amplifier.


Preventing a computer from powering the Raduino

Doug Wilner  finally got around to putting KD8CEC’s outstanding firmware on his V3 µBITX.  When he is not using his rig for other things, he leaves it on rx on WSPR.  He finds using CAT control for band hopping is fantastic.

He did not want power over the USB cable going to the raduino when the rig is otherwise switched off, so he stripped back the insulation on the USB cable, parted the shielding, and like a B movie bomb tech, he cut the red wire.

With a little heat shrink on the cut ends, some copper foil to repair the shielding, and electrical tape to replace the outer jacket it looks good as new…from 100 yards 🙂

This may not be a revolutionary break through but Doug figured it was worth sharing with µBITX constructors.


Sketch for W8TEE Morse code tutor now available to download


The source code and schematic from Jack W8TEE’s FDIM talk on the Morse Code Tutor (MCT) is now available in the Files section on:

SoftwareControlledHamRadio Group.

Please note that there are still some changes that he plans to make to the code, but there are no plans to change the hardware of the MCT.

Al and Jack consider the MCT to be Open Source, subject to the MIT Open Source agreement. (This more-or-less means that you need to leave my headers in the files.)

Note that there are multiple files in the zip file and those files must all appear in the same project directory. There are also some non-standard headers used that are not part of the standard Arduino IDE. The URL for these non-standard headers are given after their #include directives in the MorseTutor.h header file. This is to be expected because the code uses the STM32F103 (“Blue Bill”) microcontroller.

This requires you to install the STM32F patch, and there are plenty of places to find help doing that. I used “Using the Arduino IDE with the STM32F” as my search in DuckDuckGo (I’m done with Google) and found plenty of entries from which to choose, including video and written guides.


Another new uBITx build … from N0KAI

Jeff N0KAI  shows off what he calls his “fun build”.

Mods to his µBITx include the Nextion 4.3″ screen , a 2.5 MHz high-pass filter for BCI,  a Kit Projects AGC board, and fidelity mods to the LM386 amp.

He says that the Uniden CB mic works, but its gain is a bit low, which needs to be fixed. CW, however, works fantastically apparently.

Jeff brought the RF gain control forward to the front panel on a concentric potentiometer with the AF gain control.  He really likes that, but direct soldering shielded cable to the SMT potentiometer pads on the board was a recipe for disaster. Within hours, the ground pad lifted even though he was gentle as hell with it.

Jeff suggests that it would be nice to see a future revision of the Kit Projects AGC board include better solder points or even headers for all the wires, as he tacked header pins to the pads for the switch connections. He notes, however, that the AGC circuit itself works very well.

Jeff concludes by saying “This is gonna be a fun QRP rig for Field Day…”