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Hello, I discovered this project last Fall and this reflector even more recently. I have been reading the discussions about "Display Noise' and"SPI issues" with much interest and since my experience is a bit different I will share it here. I have built a V12 radio with RF, Main, and Front panel boards in an AI6YM chassis, using STDVer050.2 software. I originally built the radio with a TFTM070A3-5 v4.0 (7") display and immediately noticed significant amounts of noise not normally heard from a radio with the antenna disconnected. This noise was below the level of the noise coming from my antenna on bands up through 15M, but above that the radio's internal noise was higher than antenna noise. I made a simple probe from a piece of coax by removing 1 " of the shield from the end, connected the other end to my spectrum analyzer, and probed around the inside of my T41. I discovered what I believe to be a smps in the upper right corner of the rear of the display running at about 1.15 MHz. This smps exists in both the 5" and 7" displays. The 6th harmonic of this can be heard at the bottom of 40M and the 12th harmonic at the bottom of 20M; neither can be heard with my antenna connected but are very noticeable with the antenna disconnected. I discovered very high levels of EMI radiated from the middle area of the circuit card on the back of the display. The spectrum of this EMI starts in the HF band, peaks around 160 MHz and has very significant strength in the 6M and 2M bands. I then noted that the layout of the boards in my chassis places the receive input circuitry about 2" from both the smps and the display EMI source. Not good! I then clamped my coax to the chassis such that the 1" "probe" was right next to the receive RF input circuitry. I then made a simple shield/cover for the 7" display. In doing so, I discovered a few issues with the displays. First, the pads around the four mounting holes are not connected to the circuit ground, nor are they even connected to each other. On the 7" display, the four oblong, exposed, pads across the top are connected to the circuit ground, but the four across the bottom of the board are not, nor are they connected to each other. When I then measured the noise from the probe with and without the shield in place on the 7" display there was some improvement, most noticeably on the smps noise, but the noise on the upper HF bands was still higher than the noise from the antenna. I then looked at the 5" display. All four of its exposed, oblong, pads are connected to ground. I soldered small clips (from a Harmon EMI kit) to each of those four pads and made a shield to fit in those clips (see attached picture). I had to run a short wire from each clip to the closest mounting post to tie the shield to the chassis. This provided a very significant reduction in the level of noise present at the receive input circuitry. To quantify the improvement, I measured the radio's sensitivity on each band and converted that to a receive noise figure. That can be compared to the level of noise that I measure from my antenna. This data is shown and graphed in the attached Excel file. The T41 receiver is very quiet now up through 10M. 6M is much improved, but further improvement is desired. Perhaps the cable..., perhaps moving the RF board away.... 73, John W2TX

As Jack mentioned in a recent post, I've accepted the weighty responsibility for maintaining the code for the T21 V12 radio. I've learned so much by participating in the T41 project, I'm happy to help keep this project going so others can get as much enjoyment and knowledge as I have. Here's how we're going to manage the code. Jack and Al have written a fourth and final edition of their book describing the T41 theory and operation of the T41 radio. We will maintain Version 66-9 of the code on GitHub in a state that reflects the book so that anyone buying the book in the future can download code that corresponds to the structure and features described in the book. We'll fix bugs, but not add any new features to this code. It will live here: https://github.com/KI3P/SDTVer066-9 New features and changes to the code will be hosted in a new repository on GitHub: https://github.com/KI3P/T41-V12-SDT At the moment these two repositories are identical (other than a change in the name of the sketch). Expect them to diverge over time. So what comes next? A lot of discussion in this forum over the last few years has centered around the display and the need to restructure or reformat the code to make it easier to change this code. Similarly, the changes to the hardware between V11 and V12 necessitated making many changes sprinkled through the code base. Updating the code to accommodate changing hardware becomes very challenging. Both of these issues are derived the same root cause: the software is not structured in a way that abstracts the hardware implementation. Before leaping into any major feature upgrades, I think that restructuring the code to make it more modular and hardware-portable would be a good idea. So I'm thinking a lot about how the software works and what a different architecture might look like.

I'm looking for test equipment suggestions. I have an oscilloscope, DVM, LCR meter but need enough equipment to at least finish this T-41...doubt I will live long enough to build anything more complicated ;-) In the DSP and SDR book they mention an audio signal generator with quadrature and a spectrum analyzer. Any suggestions on models that won't break the bank but are sufficient for building, testing and tuning the T-41? Anyone advice on this signal generator, not sure if it can generate quadrature? https://www.amazon.com/Professional-Generator-Seesii-Precision-Dual-Channel/dp/B08T9H9FBY/ref=asc_df_B08T9H9FBY?mcid=b9e572b8f8e63e6fbdcf4c21c805b61f&hvocijid=15043490532578762466-B08T9H9FBY-&hvexpln=73&tag=hyprod-20&linkCode=df0&hvadid=721245378154&hvpos=&hvnetw=g&hvrand=15043490532578762466&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9002666&hvtargid=pla-2281435177858&th=1

Well, after a long, arduous (my opinion!) but enjoyable journey, I finally got on the air. 10 watts, EPA into Southern Louisiana using a home brew 20M vertical dipole, thru 50' of coax. RST of 52 (I'll take that). I really wasn't sure how well my HT mic would work, but apparently it did well. V12, Ver66.9. Plenty of signals booming in, crystal clear. Mostly from down south, but one from CA. Of course most were running 1KW. Thanks everybody for the help that was provided. Mark KU3O

Completed RX and TX IQ cal all working fine. I went into menu to change display options, as soon as menu came up it returned went back to spectrum display which was only partial display. Now it reboots on its own every few seconds and display is only partial. Locked up power cycle does not help. Tim W4YN

I recently did some ADC measurements in preparation for an update to my Audio VNA. I mention it here as I think it has some stuff of interest to the T41 project. The measurements are on-going, but as of now included the SGTL5000 (ADC side)and the PCM1808. I believe it was the T41 use of the PCM1808 that got me to look at that part---thanks. The web page for the study is https://www.janbob.com/electron/Codec/CODECTest.htm For this group, one interesting element that came out is that the PCM1808 produces 24-bit output data, but this is lost back to 16 if you input I2S via the Teensy AudioInputI2S followed by a Q15 to F32 conversion. If you do the input via AudioInputI2S_F32 of the OpenAudio_ArduinoLibrary, the F32 library, it will include all 24-bits automatically, as well as saving a conversion. Questions, comments and corrections are all appreciated. Bob W7PUA

Greetings All, I don't see much mentioned lately regarding the MCT, but having recently purchased the 'Microcontroller Projects for Amateur Radio' book (via Amazon); I've decided I would like to build an MCT of my own. I've been a licensed ham since 1971 and would like to take one last(?) crack at CW. I've been searching the web for either a kit, or at the very least a PCB (as mentioned in the book) but so far haven't found anyone (in my hemisphere) currently offering one that goes with the text. I also understand that the gerbers, schematics, source code etc., have been made available in the files section and github. I just thought I'd ask before messing up square feet of perf board, whilst attempting to wire up the pieces-parts. I also considered trying to have a PCB made, but I've only ever done that once. The results were good enough, I simply don't need a handful of boards when one will suffice. :) Sorry for the ramble. Any advice...? Thanks. 73, Vern - N7GTB

I've been wrestling with the datasheet for this 7" display. I checked all the jumpers and it is configured as 4-wire serial. It seems like there is a typo in the datasheet, as they have two J2 connectors, one with 10 pins and the other with 40 pins (labeled Parallel/Serial Interface and CTP (capacitive touch panel) interface. I want to double check if my assumptions are correct in the following connections to the display: Use only the first 8 pins of the 40 pin connector Pin Number (J2 AKA J3 on the device) 1 and 2 VSSGroundGND 3 and 4 VDDPower SupplyVCC 5 /SCS Serial Mode Chip Select (/CS), Low activeC/S 6 SDO 4-wire SPI Data Output (MISO)MISO 7 SDI 4-wire SPI Data Input (MOSI)MOSI 8 SCLK SPI Clock (SCLK)SCLK I've attached the datasheet. Thanks for you help.

Hi everyone. Its been a LONG time since I've done any compiling, so I don't know how to go about understanding the meaning of : undefined reference to. . . Would someone be so kind to enlighten me? Thanks, Duane - K5CA