Work in progress

Contest transceiver

Teensy 4.6 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 4.6 to the rescue

01.

First Teensy 4.6 controller

First Teensy will be used as IQ audio processor delivering 100-1500 Hz audio, rejecting unwanted side band.

02.

Second Teensy 4.6 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.

V 1.0 January 2022

The Bad, the Good and the Ugly !

  • PCB will have to be redesigned. Also, some MLCC smd  capacitors produce audio noise upon vibrations. Teensy audio shield stereo output is not using ground but it is floating.
  • Due to electronic components crisis, will have to wait some time for variable RF attenuators.
  • 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 !