KF5N Radio Experimentation Site
T41 Blog
A new version QSE2DCEZ transmitter module PCB design is released:
PCM1808 ADC Module Modification
The PCM1808 module, as shipped, includes RC low pass filters on both inputs. The resistor value is 10kohms, with a capacitor value of 330pF. This creates a 3dB cut-off frequency of about 48kHz.
The experiments continue! Here is a demo of a T41-4 receiver which is based on the TAC5212 codec IC:
A new version QSD2EZ receiver module PCB design is released:
I needed to revise the rear panel of my T41 to fit the T41-2 power amplifier. Rather than tweak the design with FreeCAD, which is what I have used before, I decided to give “OpenSCAD” a test drive. A few weeks ago I purchased this book:
T41-2/T41-3 Off-The-Shelf Modules
This is a list of example off-the-shelf modules which are used in the T41-2 and T41-3 series of T41 radios. These modules are easily found on eBay, Amazon, Aliexpress etcetera.
QSD2 V1.0 Regulator Circuit Change
This note covers a recommended change to the QSD2EZ V1.0 circuit. The board will probably work well without this change, however, in some boards the 2.5 volt regulators may not properly regulate. This is due to the very light load on the regulators. Also, I recommend removing one of the regulators, and installing an option “DNP” (Do Not Place) so that the circuit works with a single regulator.
From the very beginning of the T41 project, Al and Jack recommended “Bourns” brand encoders. I agree that they are 100% correct on this.
T41-2 Low Power Amplifier Silkscreen Error
The back side silkscreen of the T41-2 Low Power Amplifier has an error in the silkscreen. This is on the back side.
The T41-2 Switch Matrix Board V1.0 is released:
The T41-3 Main Board V1.3 is released.
T41EEE.93 Arduino Firmware Released
A new version of T41EEE is released here:
https://github.com/Greg-R/T41EEE
T41EEE.93 adds an iambic keyer. This keyer is loosely based on this project: