In this video I do some playing around with the ESP32-A1S module which has an ESP32 uController and an ES8388 audio codec on board. I bought mine from Aliexpress for about $4 each (no affiliation) https://www.aliexpress.com/item/2251832759134684.html?spm=a2g0o.order_list.0.0.1b631802RoYkxH&gatewayAdapt=4itemAdapt Heres some links to the documentation available from the manufacturer https://docs.ai-thinker.com/_media/esp32-a1s_v2.3_specification.pdf https://docs.ai-thinker.com/en/esp32-a1s Heres that site that allows you to determine whether you have the ES8388 or AC101 version https://www.deeptronic.com/store/blackstomp-core/esp32-a1s-ai-thinker-audio-module/ Here's that USB to Serial board https://www.amazon.com/gp/product/B00IJXZQ7C/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1 and a great article on the RTS/DTR circuit https://owenduffy.net/blog/?p=21574 My github repo for the circuit https://github.com/thaaraak/esp32-a1s/blob/main/esp32-a1s.pdf My earlier projects for the simple sine wave and phase shift https://github.com/thaaraak/ESP32-IQ https://github.com/thaaraak/ESP32-ES8388 0:00 Intro 1:20 A look at the ESP32-A1S device 2:25 How to tell the ES8388 and AC101 varieties apart 3:20 A look at the ESP32-A1S under the RF Can 4:16 The pins available 6:01 The module with soldered connections 6:32 How to program the board using a USB to Serial adapter 7:58 A schematic walkthrough showing connections 9:38 The Pins used to connect between ESP32 and ES8388 10:33 Walkthrough of the module on a protoboard 11:32 The simple sine wave example in code 12:52 The simple sine wave example in action 13:44 Phase shift example in code 17:17 The simple sine wave example in action 19:25 Wrapup ... https://www.youtube.com/watch?v=bEPe8Pm1mdw

This is the final video in the receiver side. I'll move on in the next videos to a phasing SSB exciter. I ended up with an 8 pole Chebyshev filter the design files for use in the filter design tool https://tools.analog.com/en/filterwizard/ are here: https://github.com/thaaraak/Tinypico-Radio/tree/master/filter Just use the "load" button The kicad schematic and board is here https://github.com/thaaraak/Tinypico-Radio/tree/master/kicad/Receiver I have included a pdf of the schematic also ... https://www.youtube.com/watch?v=zBK2wiLinWk

In this video I build the receiver portion of the QDX digital radio from QRP Labs https://qrp-labs.com/qdx.html Here's the manual and operating guide https://qrp-labs.com/images/qdx/manual_1_11.pdf https://qrp-labs.com/images/qdx/manual_operation_1_03.pdf 0:00 Intro and QDX description 1:00 Walkthrough of board 2:27 A look under the microscope 4:18 Walkthrough of schemartic 7:36 My build order (done at my own risk ;) ) 11:07 uController up and running 13:40 Quick walkthrough of LPF switching 16:17 Building the LPF 17:10 Winding the LPF toroids 18:00 Testing the LPF toroids 16:35 Installing L12 the multi-tap bandpass inductor 23:08 Winding the Trifilar splitter T2 26:06 Determining T2 leads 28:46 *** On the Air *** 30:40 Doing some voltage measurements - LPF 32:47 Testing X5 33:57 Testing X6 34:45 Walkthrough of WSJTX setup and wrapup ... https://www.youtube.com/watch?v=KmpNxhZiJXg

In this video I use the SA818 board which is a single board handheld with can transmit and receive on 2m (there is a 70cm version). Documents for the SA818 are here https://github.com/thaaraak/rda1846/tree/master/documents I have read that this board does not meet FCC spectral purity rules I do plan on putting a lowpass filter before transmitting which I haven't done yet. The board itself is available from various sellers - here for example https://www.banggood.com/SA818-VHF-Ultra-High-Frequency-1W-Wireless-Walkie-talkie-Module-Intercom-Module-Embedded-p-1411562.html?cur_warehouse=CN The code is very straighforward https://github.com/thaaraak/rda1846/tree/master/SA818 but I would have gotten nowhere without this repo: https://github.com/darkbyte-ru/SA818 The 2560 connects to the SA818 via the Serial1 pins. I also have a simple audio amp after the SA818 based around an LM386 ... https://www.youtube.com/watch?v=gDYYR8VvHMI