ERVARC members learn by building. These are the projects the club can offer as group builds, demonstrations or one-on-one help with an Elmer. Workshop dates will be announced once they’re scheduled. Tell us which ones you’re interested in and we’ll plan around the most requested.
- Vote for the next workshop
- Antennas & Feedlines
- Electronics & Kits
- Station, Power & Go-Kits
- Digital, SDR & Networking
- Operating Projects
- Antenna Design Notes
Vote for the Next Workshop
Help pick what we build or learn at the next meeting. Choose one project from the list below. The most popular choice is the one we’ll plan for.
Next meeting: date TBD
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Antennas & Feedlines
| Project | Level | What you’ll learn |
|---|---|---|
| Coax Connector Workshop Install PL-259, BNC and N connectors the right way: solder-type and crimp. Test every cable you make. | Beginner | Soldering, crimping, continuity and SWR checks |
| 2 m / 70 cm J-Pole or Roll-Up Slim Jim A simple, effective vertical for the local simplex frequencies. Copper pipe for the house, ladder line to roll up for the go-kit. | Beginner | Measuring, cutting to frequency, SWR tuning |
| 40/20 m or 80/40 m Dipole Cut-to-length wire, center insulator and choke. The best first HF antenna. | Beginner | Antenna length math, trimming, using an analyzer |
| NVIS Dipole for Emergency Comms A low-mounted 40/80 m dipole that covers the region from 0 to 300 miles. Ideal for ARES® and Winter Field Day. | Beginner | Near-vertical skywave, portable deployment |
| 1:1 Common-Mode Choke Coax wound on a ferrite core to keep RF off your feedline and out of the shack. | Beginner | Ferrite materials, common-mode current |
| 49:1 End-Fed Half-Wave Transformer The transformer behind the popular EFHW antenna. One wire, several bands, no tuner on its harmonic bands. | Intermediate | Toroid winding, impedance matching, power ratings |
| 9:1 Unun for Random Wire Pairs with a non-resonant wire and a tuner for quick multiband portable operation. | Intermediate | Trifilar winding, choosing wire lengths |
| Magnetic Loop Antenna Compact, tunable loop for small lots, apartments and portable use. | Intermediate | High-Q circuits, variable capacitors, safe power levels |
| 2 m Tape-Measure Yagi A directional antenna made from steel tape measure and PVC. Built for fox hunting and satellites. | Beginner | Yagi design, directivity, hand-held DF |
Electronics & Kits
| Project | Level | What you’ll learn |
|---|---|---|
| Code Practice Oscillator A small tone generator and key for learning Morse code. A great first soldering kit. | Beginner | Through-hole soldering, reading a schematic |
| Homebrew Straight Key or Paddle Build your own key from hardware-store parts. | Beginner | Mechanical design, CW basics |
| 50-Ohm Dummy Load Test your transmitter without putting a signal on the air. | Beginner | Resistor networks, power dissipation |
| QRP SWR Bridge A simple resistive bridge for tuning low-power rigs safely. | Intermediate | Bridge circuits, matching |
| CW Audio Filter & Amplifier Narrow audio filter that pulls weak CW signals out of the noise. | Intermediate | Op-amp circuits, PCB assembly |
| Return-Loss Bridge / Directional Coupler Measurement tools for checking antennas and feedlines. | Advanced | RF measurement, calibration |
| QRP Transceiver Kit Build a complete low-power CW rig from a kit and make contacts with a radio you built. | Advanced | SMD and toroid work, alignment, troubleshooting |
Station, Power & Go-Kits
| Project | Level | What you’ll learn |
|---|---|---|
| Anderson Powerpole Workshop Crimp and assemble Powerpoles, the standard DC connector for ham gear. | Beginner | Crimping, polarity conventions, fusing |
| DC Power Distribution Box Fused Powerpole panel to run several radios from one supply or battery. | Beginner | Fuse sizing, wire gauge, voltage drop |
| Portable Go-Box A grab-and-go station: radio, power, antenna and accessories in one case. | Intermediate | Station planning, mounting, cable management |
| LiFePO4 Battery Pack Safe battery power for field and emergency use, with fusing and a proper charger. | Intermediate | Battery chemistry, BMS, charging safety |
| Station Grounding & Bonding Bond your station for safety and lower noise, following current NEC guidance. | Intermediate | Lightning protection, bonding, RF noise |
Digital, SDR & Networking
| Project | Level | What you’ll learn |
|---|---|---|
| FT8 & Digital Modes Setup Connect your radio to a computer and make contacts with WSJT-X. | Beginner | Sound card interfaces, audio levels, time sync |
| Winlink Email Station Send email by radio without the internet. A key emergency comms tool. | Beginner | Winlink Express, VARA/packet, gateways |
| RTL-SDR Receiver Station Turn a USB dongle into a wideband receiver. Listen to HF to UHF and track aircraft with ADS-B. | Beginner | SDR software, antennas for reception |
| AllStarLink Node Build a Raspberry Pi node and link it to the club’s node 409180. | Intermediate | Linux, radio interfacing, networking |
| APRS iGate / Digipeater Raspberry Pi with Direwolf to relay position reports to the APRS network on 144.390 MHz. | Intermediate | Packet radio, Linux services, APRS |
Operating Projects
- Fox hunting: find a hidden transmitter using your tape-measure Yagi and an attenuator.
- Amateur satellites: work the FM satellites and the ISS with a handheld and a directional antenna.
- Parks on the Air (POTA): take a portable station to a local park and activate it.
- Antenna day: bring an antenna and an analyzer and compare designs side by side.
- Emergency comms drills: practice net check-ins, Winlink and NVIS from go-kits.
Antenna Design Notes
Quick reference for the antennas above. Lengths are starting points: cut long, then trim while watching SWR on an analyzer.
End-Fed Half-Wave (EFHW)
- Length: about 66 ft for 40 m, which also works on 20, 15 and 10 m. About 33 ft covers 20/15/10 m.
- Transformer: 49:1 (some builds use 64:1). The feedpoint of a half-wave wire is about 2,500–3,500 Ω.
- Core: FT140-43 for low power; FT240-43 for 100 W SSB. Use lower power for high-duty-cycle modes like FT8.
- Tips: a short counterpoise and a choke on the coax help keep RF out of the shack.
Random Wire with 9:1 Unun
- Length: choose a non-resonant length (common picks: 29, 35.5, 41, 58, 71 or 84 ft) to avoid hard-to-match half-wave lengths.
- Matching: a tuner is required. The 9:1 brings the impedance into its range.
- Counterpoise: at least one radial or counterpoise wire at the unun.
Dipoles: Inverted-V, Fan and Trap
- Length: total length in feet ≈ 468 ÷ frequency in MHz.
- Feed: coax with a 1:1 choke balun at the center; the feedpoint is close to 50 Ω.
- Inverted-V: one center support; keep the angle between the legs at 90° or more.
- Fan dipole: several dipoles on one feedpoint. Spread the elements apart and expect to retrim, because they interact.
- Trap dipole: LC traps let one wire work on two bands. It’s shorter than a full-size dipole but has narrower bandwidth.
Verticals
- Quarter-wave: fed directly with coax; needs radials. More radials give better efficiency.
- Non-resonant: a vertical with a 9:1 unun at the base and a tuner covers many bands from one radiator.
Larger Projects
- Hexbeam: a lightweight multiband beam (usually 20–6 m) that turns with a small rotator.
- G5RV: 102 ft top fed with a ladder-line matching section, then coax. Needs a tuner on most bands; add a choke where the ladder line meets the coax.
Transformer Basics
- Impedance ratio = turns ratio squared. A 9:1 unun has a 3:1 turns ratio (usually trifilar). A 49:1 has a 7:1 ratio, typically 2 primary turns and 14 secondary turns.
- Core mix: type 43 ferrite is the HF workhorse. Larger cores handle more power and run cooler.
- Test it: check with a dummy load on the far side and an analyzer before putting it on the air.
Request a Workshop
Cast your vote above, or email elkrivervalleyamateurradioclub@gmail.com with your call sign and the projects you’d like to build. We’ll schedule workshops around the most requested projects and post the dates on the Events page.
Have a project of your own, or want to lead a build? Bring it to a meeting. Members teaching members is what the club is about.
Resources
- The ARRL Antenna Book: the standard reference for antenna theory and construction.
- ARRL Handbook: electronics, kits and station building.
- Antenna modeling: MMANA-GAL (free) and EZNEC let you see a design’s pattern and SWR before you build it.
- QST and ARRL Technical Information Service: project articles and technical Q&A at arrl.org/tis.
- Club Elmers: one-on-one help with any project. See Elmers.