V 1.0 January 2022
The Bad, the Good and the Ugly !
Work in progress
Contest transceiver
Teensy 4.1 SDR
Yet another hamradio project I am working on
As hamradio, I love buiLding things !
Even it will not be a factory like tranceiver, I will give my best to be as small as possible, only few bands
Will be CW only, 80 to 20 meters bands. Also, will be interfaced with computer via USB and Kenwood emulated codes. No fancy waterfall, no zillions of menus to get lost into !
2x FST 3257 + 2 x AD8599 frontend
2x4 channel multiplexers used as IQ mixers, SI5351 and flipflop as IQ VFO followed by 2 x AD8599 high gain / low noise audio stages. The output will be feed into digital processing board
To keep it simple stupid, only CW mode will be on both transmit and receive
Having a 15 W output MOSFET power amplifier available, will filter / reduce the signal in such way that only 10 W constant output will be transmitted in all bands.
Tennsy 4.1 to the rescue
01.
First Teensy 4.1 controller
First Teensy will be used as IQ audio processor delivering 100-1500 Hz audio, rejecting unwanted side band.
02.
Second Teensy 4.1 controller
Another Teensy will be in charge of T/R switching, PC connectivity, PBT filter, noise reduction and AGC output voltage with raise time, knee time and time delay.
03.
Digital controlled AGC
While a direct conversion receiver can be hard to AGC control and not willing to use software audio AGC leaving front end unprotected, Teensy will control a chain of RF variable attenuators directly at antenna port, hopefully in 0-120 dB range.
04.
Transmit Board
2 x Mitsubishi RD15 mosfets board, purhased from Ebay long time ago. It is more than capable to withstand output shorts and high swr without any dammage. ( I did test that ! ). It will be input and output filtered with Chebyshev 5 poles filters., also no relays will be used on T/R but powerful FET switches.
05.
Display
Not sure yet , but I am in keen using Nextion 7 inches capacitive display where all graphic code is written inside it, so no heavy burden on Teensy.
“Good things happen when you set your priorities straight.” Scott Caan
While being caught in multiple projects like shack building, antenna tower, smart home controller as well as smart antenna controller, I have to prioritize my projects not leaving family aside.
Special thanks
for outstanding work
For intensive work, passion, will to "GET THE JOB DONE !" , my gratitude goes to Charlie Morris, a True self-learning hamradio. Great job Charlie !
Ian, your English is the most understandable, pleasant and straightforward I have ever listen from a hamradio . PCB art true artist also, same gratitude goes to you man !
