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T41 transmit died
So - I was trying to break in to one of those endless 40M roundtables. They weren't hearing me. Even with the amp. Looked over at the power meter - zero output! Huh? Switched to CW, hit the key - normal output. Stuck my oscilloscope on the IQ inputs to the RF card - no talky-waveform. OH, no! Did something break? Do I have to do hardware troubleshooting? Waah! Nope, I don't. The problem is the transmit equalizer. For some reason, if you turn it on, it sets all the bands to zero. Set them up properly, go back to transmit...and they're zero again. Guess I'll upload Al's latest and see how that does. WRT equalization: I'd like to have a couple quick-modes for that: "Ragchew mode" - nice flat response, mellow lows - and DX/Contest mode - lows suppressed, mid-highs accentuated for punch. Maybe I'll code something. - Jerry, KF6VB
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Feedback into T41
6
Hello all, I was trying out my station with a second antenna - an 65-foot End Fed Half Wave. I had built it to the kilowatt level, with a big toroid core on the matching transformer. Instead of a counterpoise, I used an 8-foot ground rod - the kind they sell to ground your house. Probably needs a counterpoise also... The far end of the antenna is supported by a monster oak tree on my property. Got it up there with a slingshot. I hooked up a spare MFJ998RT autotuner to the EFHW and thence to my station through a 40-foot length of Davis Buryflex RG/8. It worked fine on the base T41 - decent SWR on 40, 20 & 15M. And it actually worked on 80 - although the autotuner was clearly struggling. HOWEVER, when I turned on my KW amp, I pushed the PTT, and the power immediately rose to 950W or so out...without me talking. And somebody on the frequency said "what's that noise?". I figure that RF is getting back into the T41. Probably need to stick a counterpoise on the EFHW, and maybe a common mode choke. My main antenna does not give me any such problems; it's a trap vertical up the hill, and it has an excellent ground - an Ufer ground, consisting of 80 feet of thick copper wire embedded in a 10 by 70' concrete slab. I'm trying the EFHW to see if it's any quieter than my vertical. So far, it's about the same. - Jerry, KF6VB
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[AmateurRadioBuilders] RP Pico 2
5
I actually have a couple pico 2's. No wifi, though. It does do SPI, so it could control our current display - assuming that there's an RA8875 library available. The first step would be to isolate all access to the display. Make sure it's all in one file. I would use C++ objects to encapsulate it. Pages and items. A "page" would be an entire display - say the normal radio display. Or the BIT test display. Or the IQ calibrate display. An "item" would be one of the things that the page displays. Once something like that was in place, it would be straightforward to substitute "page" calls with calls to a different file that squirted the info out to the Pico. The object of the exercise is to minimize this info. Only the Pico would know exactly where on the screen something goes, for example. So if the Teensy can just say "display the main screen" to the Pico, that's a lot less work for the Teensy. There's no way around sending the individual readings for the spectrum. But the Pico would maintain the waterfall. The Pico supports hardware debug, so development could be relatively fast. A quick websearch revealed that there IS a working RA8875 library for the Pico. - Jerry, KF6VB
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[AmateurRadioBuilders] Alternative to Pico?
2
*** Hardware debug? - Jerry, KF6VB
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RP Pico 2
2
All: I just read that the RP Pico 2 is now capable of running at 200MHz, up from 133MHz earlier. Using CMake, the new speed setting in the compiler is a symbolic constant: PICO_USE_FASTEST_SUPPORTED_CLOCK=1. I don't know if the Arduino IDE recognizes this or not. There's been interest here in using the Pico as a second I/O processor in the T41. The Pico W has 26 I/O pins, 2Mb of Flash, and WiFi/Bluetooth support. No price was given for the Pico 2 nor did it say anything about WiFi/Bluetooth support, but the standard Pico W is about $8-$10. If I see additional info, I'll post it here. Jack, W8TEE -- Jack, W8TEE
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I was furtunate enough to received from Ron AG1P a T41 kit back in December of 2023. The plan to get to it in early 2024 didn't work out, I've just this last week gone through the box and have a good start on the book. Before I dive into building it are there modifications or other that I should do right away? The 5 inch display and other not included in the box I should get on order ASAP. Retirement should have happened in 2020, hopefully this later this year. Ron VE8RT -- Ron VE8RT <ve8rt@...>
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T41 BPF 6m confusion
3
I started to wind the coils for the 6m band and am confused about L601, L603, and L605. The directions say L601 and L605 are 39nH, 5" 24AWG, 5 turns on a 1/8" drill bit. However, L603 is 24nH, 4" 24AWG, 7 turns on a 1/8" drill bit. How can 7 turns require less wire than 5 turns and how can 7 turns have less inductance than 5 turns? Bob W3RDL -- This email has been checked for viruses by Avast antivirus software. www.avast.com
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Just some Friday sharing¡ Here is a finished dual encoder board with 3D Printed knobs (all out on the GITHUB). Replaced TWO encoders. One ribbon cable from the encoder board to the Fron Panel Electronics (FPE) board (one of 8 possible FPE boards BTW!). I guess I should make a video of the combo AF/RF gain on one encoder¡ Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. email: bill@...
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[AmateurRadioBuilders] RP Pico 2
2
Hi Jack, do you have any links where we can see that info about the *pi pico 2*? afaict, news has been released that the original Pi Pico has been bumped from 133MHz to 200MHz. I don¡¯t see anything about the Pi Pico 2 though? Having said that, the Pi Pico 2 is interesting because¡ - it already clocks at 150MHz - it has FPU and DSP on the arm cores - is available as a ¡®W¡¯ version already (for about ?6.60 in the UK) with 4MB flash and 520KB RAM I won¡¯t be surprised if a speed bump for Pico2 is announced later, but it has taken some time for that to come for Pico(original), and the Pico2 has not been out that long, so I guess we wait and see. Graham, 2E0WRW
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All: I've also experimented with the XIAO processor from Seeed Studio. It's about the size of your thumbnail and costs $5: It has 256K of flash and 32K of SRAM with 19 general I/O pins, ADC/DAC pins. I have used earlier versions of this microprocessor and is compatible with the Arduino IDE and libraries...I haven't found a library yet that didn't work, but there may be some. I use this over the Nano--the clock is 2x faster, a lot more memory, and a much smaller footprint. I don't know if it speed is fast enough for T41 I/O duties. More specs at: https://www.seeedstudio.com/Seeed-XIAO-RA4M1-p-5943.html Jack, W8TEE -- Jack, W8TEE
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V66.4 Calibration Instructions
Here is a revised version of the V66.4 calibration PDF. Al AC8GY
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Hi Everyone, I have attached the latest version of the T41 code. I believe it is in good shape but has yet to be thoroughly vetted. I am posting it now, ahead of a formal release to enable some of the builders who are having a difficult time with earlier versions to run a known working version. This version has the latest Calibration routines; however, it has not gone through Jack's review yet. Jack and I agreed to put this out temporarily so you can give it a try. Please report any issues to Jack and me. We will review the code and post a final release in a week or so. I am also attaching a copy of the Calibration instructions PDF. You will also find abbreviated instructions in each calibration routine. Note that this is for V12.6 hardware only. Some of the calibration routines will not work with V11 or earlier. It is good practice to erase the Teensy4.1 prior to up-loading, since much of the EEPROM has changed. To clear all memory, press and hold the Teensy load button until the LED by the USB port flashes. Release and wait until the main LED begins to flash. The Blink program is then loaded and EEPROM is cleared. In the code go the Setup in the .ino file and uncomment the line at 3130 the first time you upload. Comment out that line the next time you upload. In the IDE select "Optimize: Faster with LTO", set the USB type to "Serial". You may have to select the Teensy port the first time you upload. We encourage everyone to upgrade to V12.6 Main and RF boards. The V12.6 performance is greatly enhanced. Good luck and let us know how it works for you. Regards, Al Peter AC8GY
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T41 SDT Version 66.3 with Calibration
3
This version fixes the button response problem in Receive Cal and a couple of other small issues. Al AC8GY
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Last evening, I finally got my version of the T41 on the air for an extended period of time on 75M. Talked all over the US and even down to British Honduras with my home brew amp running about 800W. I call it the "Franken" T41 because the RF portion is not a T41. This is my FPGA implementation with a DSPic CK doing the actual demodulation/modulation. Sensitivity is such that I can hear a -127dB signal; low, but it is there. On all bands the antennas generate way more noise than the rig. The FPGA splits the RF signal two ways: One set to a DAC for the panadapter and one set to the DSPic via I2S. Other than the panadapter signals, all analog "audio" is at high-level. No calibration is needed; the beauty of getting to digital as soon as possible. The UI is run by the Teensy using much of Al and Jack's code for noise reduction and equalization displaying on a 7" capacitance touch screen using an 8bit bus. The panadapter only displays +/- 48K as I like that display format the best. The display is not the ones used in the T41 as the capacitance touch "areas" of those displays are much larger than the one I am using and I need that resolution. No buttons on the front panel. Touch panel handles all "buttons" including band and mode changes. CW keying is crisp and the rise/fall times are handled totally via software in the DSPic. Built-in Iambic keyer. I'll get some internal pics up later today. I should receive a PCB today that has the Teensy in place of the DSPic... Next project and we'll see how that goes. I am using Bill's BPF, LPF and control board. The control board is modified slightly to provide for a receive antenna so I can attach my Beverage. The BPF is only on the RX path as my transmitter is squeaky clean before the 100W PA. The PA board is one I got from Glenn, VK2PE many moons ago for another project. I want to thank Al and Jack for putting this out in the public domain and for Bill and Oliver doing the boards. I get great compliments on the audio and the cleanliness of my signal. Russ NQ0U
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All boards complete (Except PA) and building ked out Biggest headache was caused by using Chinese Long pin header in Teensy. All kinds of issues croped up. Changed to Long Pin headers made correctly with almost square pins not pins stamped from thin brass sheet. ProtoSupplies.com has correct headers and lots of other quality STUFF. I can now install audio hat without issue. Installing ferrite sleeves on Display and Front panel ribbon cleared hang ups. Still have some FW issues, 66 looses audio and or decode after rx calibration. Also lots of wide band noise on sections of 20m (maybe others) parts of band work ok. The experimental Hex file that I believe Jack sent me seems to be the most stable. I did mess up a few of the BPF's that was my issue and I know what to did wrong. Happy for now, I needed to get to a feel good spot before starting big project for scout camp that got ravaged from Helene. Thanks all who contributed looking forward to finishing in near future. Tim
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V010 Boards
5
Hi all, I have a set of V010 boards and the original? issue of "Software Defined Radio Transceiver". If I build the boards in accordance with the book, will I get a functional radio? 73 John M0JBA
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SDT 63-1
4
I installed all of the required libraries and compiled this version. Looks good, but when I tried to do the Receiver Calibration, it worked like the directions(some of the switches were mapped differently), but when I pressed Select to save, it returned to the normal display with a lot of the text from the cal screen overlaid and was non functional. I had to cycle power to get it working again. I tried several bands and got the same behavior, however the I & Q corrections were stored in EEPROM. Do I just need to reset the Teensy to Blink and try again, or is there a S/W problem? -- 73 to you! 73 Bob W3RDL Virus-free.www.avast.com
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160 metres
4
Can someone please explain how to turn back on 160 metres and turn off any other band in SDTVer053? I've had a go at it but it seems there are several tabs involved. Roger G8JWT
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BPF L292
2
When you get to L292 3.6 uH 20 38 T37-10 Black 20" of #28 wire, 38T on T37-10 You might want to drop down a wire size to #30 I had trouble getting the ones done with 32 turns let alone 38! #30 I was able to get 38 turns. Frim memory wire size is not that critical just number of turns. I will send SA plot of 30M later to see if it made a difference. These filters are fairly wide (I plotted 80 and 20m so far) to start with so I doubt there is much difference. Tim W4YN
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[?SDX] Digital Interface Transceiver or DIT
here's the video for it..3 FDIM 2022 Al Peter and Jack Purdum 'T41-EP CW Decoder' FDIM 2022 Al Peter and Jack Purdum 'T41-EP CW Decoder' On Sunday, February 23, 2025 at 01:08:08 PM EST, Kees T via groups.io <windy10605@...> wrote: Jack, Thank you for sending the link but I'm having trouble playing the video. Do you happen to have a copy of the presentation you could forward ? I was trying to get a Digital Interface Text Transceiver to perform Texting functions like many do with their iPhones today. The idea was to add a RF section to transmit actual Morse Code so the Text Transmissions could be manually copied. The Transceiver would require no speaker, no headphones, no key.....no audio at all. The only human interface is a keyboard on the display, Text Received, and Housekeeping data. Since you would want to reduce the RF bandwith as much as possible reduce the Dv/Dt, etc. Call that "Fast CW". Using an external ADC and FAST Microcontroller to perform ANALOG signal processing .....is it a DOT or a DAH, remove unwanted noise, compensate background noise, etc, etc and be able to dig the signal out of the muck. Only then to you confirm it was the letter "P" and send it on for display. Weak signal detection NOT nearly as well as WISPR and other small signal algorithms but an improvement. Strong signals with minimal interference are always easier to decode. 73 Kees K5BCQ -- Jack, W8TEE
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Image Name
Sat 8:39am
Sat 8:39am