Welcome to Issue #006 of Radio Waves Weekly! This week: an Arduino that transmits clean SSB with 8 components, an open-hardware SDR transceiver with PureSignal TX, a garden fence turned into a stealth HF antenna, and a broadband V wire that covers every HF band without a tuner. Plus a free antenna modelling tool the pros rely on, a satellite-ready handheld Yagi, and the ARRL DX SSB contest this weekend — right at the peak of Solar Cycle 25.
1. uSDX — Arduino Transmits SSB, CW and FT8 at 5W with Just 8 ComponentsQRP
ATmega328P directly phase-modulates an Si5351 PLL at 800 kbit/s to produce clean SSB — no mixer, no sound card, no PC. Covers 80–10m for SSB, CW, FT8 and RTTY. Full BOM under ₹2,000. A brilliant feat of DSP on an 8-bit chip.
Full build story (TA8AHL) → Assembly manual (DL2MAN PDF) → Mini-v2.6 OSHWLab PCB files →
AD9866 + Cyclone IV FPGA, 0–38 MHz, 5W. Includes PureSignal pre-distortion for splatter-free SSB — previously a $3,000+ feature. Over 500 units built worldwide. PCB from Makerfabs for ~$340 all-in. Runs SparkSDR and Thetis.
Hermes-Lite 2 technical wiki → Operator review VE2DPE → GitHub source & schematics →
SA612 double-balanced mixer replaces the old direct-sampling trick — no Nyquist folding, no phantom signals, clean 500 kHz to 1.7 GHz in one sweep. Elektor bench tests confirmed zero overload on a 20m long wire antenna.
V4 release notes & changelog → Elektor independent bench review →
Wire or chain-link fence pressed into service as a multiband HF random wire — 9:1 UNUN at the shack, remote ATU covers 40–10m. No towers, no visible wire, zero HOA objections. Works equally well with aluminium balcony railings.
Military-derived travelling-wave wire antenna: two legs spread at a shallow V, terminating resistor at the far end. Covers every HF band with no tuner. 1–3 dB resistive loss traded for wideband convenience. Deploys on two tent poles for SOTA.
6. CL-OCFD — Six-Band Dipole, Single Feedline, No Antenna Tuner ANTENNA PROJECT
Off-center-fed dipole with a centre loading capacitor covering 80/40/30/20/15/10m — no external tuner required. Feed point is 200Ω matched by a 4:1 balun. Free online dimension calculator at hamwaves.com by ON4AA.
CL-OCFD design, calculator & NEC model
7. 4NEC2 — Simulate Any Wire Antenna Before Cutting a Single Metre TOOLFree NEC-2 engine with GUI: plot gain, radiation pattern, SWR and feed impedance for any wire geometry. Model your EFHW, delta loop or OCFD and know exactly what to expect before building. Completely free, no licence required.
Beginner tutorial PDF (DL8WX) → Step-by-step tutorial (Georgia Tech) → Antenna modelling slides (KF5WBE) →
Arduino Nano + Si5351 + BS170 class-E PA = a digital-only QRP rig. No microphone, no sound card — the Nano generates TX audio itself. Kits under $40 from several vendors; open Gerbers available for DIY PCB etching.
Runs 0000–2359 UTC March 1–2. Solar Cycle 25 at peak — SFI above 200, 10m and 15m wide open. South Asia stations on 20m and 15m should find excellent long-path openings to USA and Canada throughout daylight hours.
9th annual HamSCI Workshop, March 14–15 at Central Connecticut University. 50+ talks on WSPR propagation sensing, Personal Space Weather Stations, meteor scatter, and a tribute to VLF pioneer Paul Nicholson (G8LMD). W1AW operation included.
Want to contribute? If you found an interesting circuit, a new SDR software, a helpful radio blog, or breaking ham radio news, please email me or leave a comment below. Your link might be featured in next Sunday’s digest!
