uBITX Transceiver semi-kit build

Discussion in 'Homebrew and Kit Projects' started by KD8UYQ, Aug 14, 2018.

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  1. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello All,

    There was one more mod that I wanted to try on my uBITX tested bed before moving on to building a linear amplifier for this rig. That being CAT control and a SDR based pan-adapter.

    uBITX Panadapter Display.jpg

    There are several discussions on the web pertaining to how to do the later but the former is very easy using Ian's version 1.071 firmware for the uBITX or later. In my case I am running v1.097. Go to http://www.hamskey.com/ and download the version of firmware that supports the display that you have on your uBITX. Earlier in this thread you might remember that I upgraded the standard 16 x 2 LCD display to the Nextion 2.8" color touchscreen so UBITX_CEC_V1.097_NX .hex is what I loaded into my Radiuno.

    v1.097 firmware screen.jpg

    I didn't have to do anything to implement CAT control on my uBITX once the 1.097 firmware was loaded, it is enabled automatically, at least it was on my rig. All I had to do was download, install, and configure Omni-Rig but I don't want to get ahead of myself. I will walk you through step by step what I did to get this all to work.

  2. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    The place that I choice to tap the IF from the uBITX main board to feed my SDR dongle was right before the 45 MHz roofing filter, specifically right across R16 which is the emitter resistor for Q12. Oh, don't be confused by that little stand up board with a crystal mounted on it in the picture. This is the filter that I discussed previously to reduce spurs on the higher bands. The 45MHz roofing filter crystal is marked Y1 on the main board.

    HupRF buffer Bd tap point.JPG

    As others have noticed this point gives a broader view of the selected band then after the filter plus you don't get a big bump in the middle of the display as you would if you were on other side of that filter. Now the catch is if you sample the IF at this point without some kind of buffer circuit the SRD will load down the receive circuit degrading the performance of the uBITX and the SDR device itself.

    I choice the HupRF 50MHz buffer board available from SDR-Kits.net http://huprf.com/huprf/pat-board/ Please note that the SMA connectors don't come with the board I added them.

    HupRF buffer board.JPG

    You have a RF input, a RF output, and a connection to the 12v RECEIVE supply on the uBIX main board. A convenient place for me to make that connection was by the K1 Relay. The reason that you want to use the receive only 12 supply line is to protect your buffer board and SDR device during transmit.

    12v receive tap point.JPG

    To be continued.

  3. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Alright, now that the hardware is setup it is time to download, install, and configure some software to your Windows PC. I am running Windows 10 on a hardware platform which is about six years old so you don't need anything super speedy. As I mentioned before Omni-Rig provides computer control of the uBITX so that is downloaded first. http://dxatlas.com/OmniRig/ Scroll about half way down and click on the downloads link. You will end up here.

    OmniRig install page.jpg

    Scroll about three quarters of the way down and click on OmniRig to install the software then go back to this same page and click on INI files for OmniRig. After the program has been installed click on the Omni-Rig icon to start the program. A little "fill in the blocks" page will open up that looks like this.

    Omni-Rig config page.jpg

    Ian's firmware that you uploaded to your uBITX's Raduino emulates a Yeasu FT-817 so that is the radio that you want to pick from the drop down box. The Port box is filled with whatever com port is listed on your PC when you have the Raduino plugged into your PC.

    MiniUSB connection.JPG

    com port setting.jpg

    You can see on my PC the Raduino shows up on COM3 so that is what I clicked on from the pull down arrow. Lastly, select your Baud rate. 38400 is recommended. the rest of the blocks can be left as they are. Click on OK and you are done.

    That's it for this evening I will continue on again about mid week.

    73's and Stay Safe,


  4. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello All,

    Now that Omni-Rig is installed and configured it is time to move on to the SDR software. I like HDSDR http://www.hdsdr.de/ and used it when I added a SDR based Pan-adapter to my Yaesu FT-990. Use whatever SDR software that you prefer but the following instruction pertain to the installation and configuration of HDSDR.

    Go to HDSDR website and download the application but don't run it yet. You need to add a .dll file associated with the type of SDR device that you are using to the folder where the HDSDR application is installed. In my case I am using an inexpensive dongle that I purchased from eBay five plus years ago.

    SDR dongle.JPG

    Over on the HDSDR website click on the Hardware button and scroll down until you see this list of devices. The one that works with my device is close to the bottom of the screen.

    HDSDR DLL pick list.jpg

    I clicked on the DLL link and downloaded that file to my PC then I moved it over to the file folder that contained the HDSDR program.

    SDR dongle DLL file.jpg

    The file name for my device is ExtIO_RTL2832.dll. With the SDR device connected to the buffer board at one end and a USB port on your PC on the other, go ahead and run HDSDR. You should see a display that looks like this and hear static noise coming from your PC's speakers.

    HDSDR screen.jpg

    If not or if you get an error click on the Options button then the Select Input tab at the top. Your SDR device should be selected. If it's there but not selected then click on it. If your device is not listed then you either selected the wrong device or the appropriate .dll file is not in the HDSDR program folder.

    HDSDR Select Input screen.jpg

    If you have made it this far then its time to configure HDSDR to work with the uBITX transceiver.

    More to follow.

  5. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Let's finish up.

    Click on Options then RF Front-End Configuration. Note and copy the setup that I have shown below. Because we are taping the IF from the uBITX you want to fill in that frequency in the IF-frequency box. Note that the IF frequency is entered in Hz so you have to enter 45000000 not 45 MHz. I am not sure exactly what the Global Offset does but when I was setting up HDSDR to work with my FT-990 nine kilohertz seemed to be the magic number that worked best and it also applies here.

    In the Additional Offset per Mode in Hz boxes the Offsets that I entered worked best with my v4 uBITX main board. Starting with all zeros in the boxes listen to your rig and then the speakers on the PC to see if what you hear on the uBITX matches with what you hear on the PC. If not try the numbers that I have and work up or down from there.

    RF Front-END config screen.jpg

    I should have mentioned this first. Match the setting on you PC with I am showing on the screen capture of my uBITX. click on Options then Input Channel Mode for RX.

    INput Channel Mode screen.jpg

    You want to have a check mark by Swap I and Q Channel for RX. This swaps the frequency scale so that the upper end of the band is on the right hand side of the display and the lower edge is on the left. Next click on the Options then Calibration Settings. There are four tabs at the top. Click on the one that says DC Removal Calibration for RX At this screen copy what I have shown below. Also notice that you can calibrate the S-Meter here by clicking on the S-Meter Calibration tab.

    DC Removal Cal screen.jpg

    You are almost done.

    Click on the SDR-Device [F8] button and once again copy what I have shown on the screen below.

    SDR-Device screen.jpg

    The Frequency Correction box is used to fine tune the audio quality as it comes out of your PC's speakers. On my setup I found that a value of plus 1 gives me the best sounding audio. That's It! now its time to play with all the slider controls for the audio and Frequency display waterfalls. Refer to the HDSDR web page FAQ tab for instructions and YouTube videos.

    Have fun


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