开云体育

All: It's been since last March that we've made a new source code release and a lot has happened in the interim. First, I doubled the number of Beta testers for the software and that has been invaluable in testing the software, especially since there are some minor hardware differences within the Beta group. A special note of thanks and appreciation goes to Greg (KF5N) who led the Beta effort with notable help from Len (KD0RC), Wes (AC8JF), John (G0ORX), Jack (KC7VLO), Nev (ZL2BNE), and Jerry (KF6VB). Dr. Bill Schmidt (K9HZ) has made numerous hardware additions to the project, including PCB's and a PA kit of his own design. To all of them, a huge thanks! Please note that we are now requiring a micro SD card be in place in the onboard Teensy 4.1 micro SD cardholder. Also, the preferred IDE is now Release 2.1.1. Compiles give two warnings: 1) that the memset() call has overlapping elements (I want it that way), and 2) a warning from the Open_Audio library. I don't want to wade into someone else's library code and make changes since everyone using it in their T41 would have to do the same. Just ignore the warning. Finally, if you do find a bug, post it with the same tag line as seen here. I'm going to "sticky" the post so they stay together. You will find the new code in the Files section. (Go to the File directory, double-click on the right-most column, Update, two times. This will bring the post near the top of the list.) Jack, W8TEE

I tried to automate the v12 transmit IQ calibration using the receive side of the RF board. I didn't expect much success given Oliver's previous work, but I had a backup plan that I soon switched to. I programmed my v12 T41 to control my v11 T41 over serial. Most of the required control commands are already available. The key control command that I had to add to the v12 was a request for the signal strength (currently the units only respond to a request for this). There are many ways to establish communication between the two units, both wired and wireless. While my v11 has Bluetooth, I took the easier wired approach for this proof of concept. And, instead of dealing with figuring out what hardware serial ports are still available on the two transceivers, I just modified my T41Server PC app to pass messages back and forth between the two T41s, connected to a PC over USB. Connecting my v11 T41 through a tap on a dummy load to the RF out on my v12 RF board was the final step. I don't have any pretty displays created yet, but here's the serial printout for the T41Server PC app (left) and the v12 unit (right). Currently it takes a couple of minutes to calibrate a band. This is to accommodate a delay in the communication link which at times results in a previous signal strength request being interpreted as applicable to the current calibration factors. I think the timing can be greatly improved with a proper handshake between the two units. I'll work on that next and then I'll automate calibration for all bands, similar to what I did with receive IQ calibration.

I've been working on a system to accurately evaluate HF linear power amplifiers. It took quite a while to figure out how to get the system working. Here's the first tangible results in the form of a spreadsheet: https://docs.google.com/spreadsheets/d/138sPdKcTFQpIvmHmLKDrkX9qBx5XPdpHhbpr-ZZSzzw/edit?usp=sharing There are 3 worksheets. The first "PA out cal" is nothing more than measurements between reference plane 1 (PA output), reference plane 2 (radio output), and the input of the power meter. Sheet #2 is the "Small Balun" version of the T41-2 Power Amplifier (final + driver). Sheet #3 is the K9HZ amplifier I built here a couple of years ago. PEP output powers are not as high as expected. Remember to halve the PEP numbers to get average power. Quite low! Note that the K9HZ PA drops to below 2 watts average power on the higher bands. The amplifier was tuned up according to the build instructions. The critical thing seems to be the bias current for the final transistors is probably too low at 250mA each. I've seen comments by others that the part used in the final amplifier (Mitsubishi RD16HFF1) needs quite a bit of quiescent bias current for decent linearity. Thus I've tuned the T41-2 Power Amplifier to a bias of 700mA each. You can see the total current drain in the last column of the measurements. I would be interested to compare my measurements to other's evaluations. Here is a video summary of the measurement system and procedure: The system: https://drive.google.com/file/d/1-3cjIAoKSbCHuvjIMmhjsgW8LgXUU7tV/view?usp=sharing The measurement procedure: https://drive.google.com/file/d/1W--Irsi-DzRKJorHyny76610ldFMG4Ph/view?usp=drive_link -- 73 Greg KF5N

Is there an easy way to remap some of the PB functions? Version 66.9 Tim

I am working on a 3d printed mic case, still needs some tweaking. Not my design (above my pay grade) but I think I can make a few tweaks to STL files. Tim

In the spirit of posting efforts currently underway, I have been working on a new RF board and associated driver software. In a nutshell, the new board uses the Skyworks SI5340 instead of the SI5351. This change addresses several issues. The SI5340 offers rock solid performance from 100 KHz to 250 MHz with LVCMOS outputs (employed by the prototype RF board), dramatically reduced phase noise and jitter, much improved clock symmetry (upon which the performance of Tayloe mixers depends), and much simpler application-level control software (no mucking about with the PLL, Multisynth, or phase at the application level). The new RF board replaces the 5351 with the 5340, and restores true split operation (the SI5340 has four outputs, three of which are used for RX, TX, and CWTx). The most challenging part of the software was the algorithm for setting output frequency, that is, given a desired frequency, find near-optimal numerator and denominator values for the various dividers used within the SI5340. My software employs a mediant-based algorithm attributed (incorrectly) to Farey, and efficiently produces results comparable to those produced by ClockBuilder Pro (the stand-alone program for configuring Skyworks parts). Current status: 1) Driver and driver example code complete and tested with main board and SI5340 EVB 2) T41 software (forked from V66.9) patched to ifdef choice of SI5340 or SI5351 RF Board compiling and in test 3) New RF board hardware under construction (PCBs back from China; parts on hand) For the curious, prototype schematic and board pic are attached. 73, John Bennett AE0AM

Al I noticed that the Hilbert filter coefficients in v66-9 don't exhibit the same structure as in v50 where the negative 45 phase shift coefficients are just the reverse order of the positive 45 phase shift coefficients. Can you provide the Hilbert filter design files for v66-9 and v50. Thanks Terrance

Can anyone tell me if the changes made regarding the MF frequencies are documented anywhere? Were changes made in the BOMs or assembly manuals for the affected boards? I have been unable to find them. Thanks. Dave. W0DF

After learning that Hans Summers was at Dayton Hamvention promoting his QMX which can now operate SSB using Polar Modulation, this got me thinking. Has anyone considered a T41 using Polar Modulation? How difficult would the software be to implement? I am sure I can sort the hardware side of things. John, G0SDF

By way of https://makezine.com/products/boards/m5stack-dial/ I was just looking at this https://shop.m5stack.com/products/m5stack-dial-v1-1 With my limited programming skills it would be a coin toss if it ended up on the shelf of shame or in something useful but in the right hands this could be interesting, assuming it isn't too noisy.

The T41 Information site is live at https://t41sdrtransceiver.wordpress.com and we are getting a lot of traffic. So far, just since yesterday at noon, we have gotten over 400 visits and more than 1200 page views. I just added a new photo gallery of images gleaned from this site and other places. If you want to have your rig featured on the User page, send me a photo and short paragraph describing your experience. Send to albertfpeter@... Thanks, Al