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▸ Is tropospheric ducting a myth?: 2.0 Mb pdf. These slides are from a presentation at the 2025 Central States VHF Conference. I was hospitalized and unable to present, so this talk was given by Jim Duffey KK6MC. A deep-dive analysis can be found in the Proceedings paper. ▸ High-Power, Fail-Safe Antenna Switch: link ▸ Antenna Modeling with xnec2c: link ▸ We communicate by ionspheric reflection -- not refraction: 2.1 Mb pdf. These slides are from a presentation given at the 2024 Central States VHF Conference. An accompanying paper was published in the Proceedings, but has several print errors that rendered some equations incorrectly. ▸ Doppler shift on meteor scatter pings: 451 kb pdf ▸ Meteor scatter with very short pings: 460 kb pdf. An earlier version of this paper was published in the 2020 Southeastern VHF Society Technical Journal. ▸ FSK441 vs MSK144 for meteor scatter communication at 222 MHz was the subject of a short presentation at the Central States VHF Society Annual Meeting in 2022. ▸ Synchronization in FT8: 452 kb pdf This note is based on my attempt to reverse-engineer portions of the mostly undocumented Fortran open-source code. I did not have access to protocol design documentation and this paper has not been endorsed by the WSJT-X developers. This paper was presented at the 2019 TAPR Digital Communications Conference. A video recording of the talk is available on YouTube and at Ham Radio 2.0. ▸ GS23B Tetrode Amplifier for 144 MHz: link. ▸ Reflection from ionized meteor trails at 50 and 144 MHz: 83 kb pdf |