In this quick video I walk through a 5W amplifier I built up based on this one from QRPGuys https://qrpguys.com/wp-content/uploads/2019/08/miniboots_assy_052919.pdf The github repo with the kicad and ltspice files is here https://github.com/thaaraak/IRF510-Amplifier-v2 The schematic is here: https://github.com/thaaraak/IRF510-Amplifier-v2/blob/main/IRF510-Amplifier.pdf Gerber files here https://github.com/thaaraak/IRF510-Amplifier-v2/tree/main/gerber A technical article on Harmonic Trap filters is here: https://www.internationaljournalssrg.org/IJEEE/2016/Volume3-Issue9/IJEEE-V3I9P102.pdf 0:00 Intro 0:33 Circuit walkthrough 2:49 Simulation of Filter in LTSpice 3:49 Pre-amp walkthrough 4:52 Walkthrough of Board 6:35 Some simple testing 7:57 Having a look at linearity with an AM signal 9:45 Wrap up ... https://www.youtube.com/watch?v=D4UhOmum_oU

In this video I do some DSP Phase shift processing with the Teensy 4.0 Big shout out to Charlie Morris' channel for all the inspiration. Lots of great stuff on his channel https://www.youtube.com/channel/UCSNPW3_gzuMJcX_ErBZTv2g The Teensy and the Audio Shield https://www.pjrc.com/store/teensy40.html https://www.pjrc.com/store/teensy3_audio.html Correction: I meant to say "I2S" not I2C Here's the Iowa Hills software site http://www.iowahills.com/ I am using the Hilbert Filter from this page http://www.iowahills.com/8DownloadPage.html Note I missed out a critical parameter in the Hilbert filter configuration and that is you have to put in the desired phase offset in the "Phase Add" field (i.e. +45 and -45) Here's some DSP theory pages. The convolution algorithm https://shulgadim.blogspot.com/2012/01/fir-filter-implementation.html A good reference source https://www.dsprelated.com/freebooks/filters/ Finally the code and coefficients https://github.com/thaaraak/TeensyDSP ... https://www.youtube.com/watch?v=DTO9gGOFIFY

Just a quick video replacing some blown FETs in the output stage of the QDX ... https://www.youtube.com/watch?v=zLeTwS-9wzo

In this video I do some playing around with the old school MC1496 Mixer and Modulator IC. UPDATE: I have just realised that I drew the schematic wrong at the output. I should have had the transistor base connected below the load - not above. I'll correct the schematic on github The kicad schematic is up on my github repo https://github.com/thaaraak/MC1496-Mixer Heres a PDF version of the schematic https://github.com/thaaraak/MC1496-Mixer/blob/main/MC1496-Mixer.pdf Here are the MC1496 data sheet and application notes https://www.onsemi.com/pdf/datasheet/mc1496-d.pdf https://www.mirrorservice.org/sites/www.bitsavers.org/components/motorola/_appNotes/AN-0531_MC1496_Balanced_Modulator.PDF Here is the article on the Weaver SSB receiver http://www.hanssummers.com/images/stories/weaver/library/ew1994.pdf W2AEWs great videos https://www.youtube.com/watch?v=7nmmb0pqTU0&t=634s 0:00 Intro 0:24 MC1496 Data sheet and applications 1:47 Schematic walkthrough 5:24 A look at the board and test setup 6:03 7 MHz carrier and 1 KHz modulating signal on the oscilloscope - AM 7:00 Double Sideband suppressed carrier output 7:25 Looking at the frequency content of DSBSC and AM signals 8:27 Mixing a pair of Audio signals 9:40 Looking at the frequency content of the mixed audio signals ... https://www.youtube.com/watch?v=qUNqdX6uIlw