I’ve launched RadHive on Substack—a free email briefing for my amateur-radio and electronics projects. Each edition covers what I built, measured, learned, or broke, with complete technical articles on radhive.fun. Subscribe: radhivefun.substack.com

Dooi: a DIY desktop robot with animated eyes and tracked movement Dooi is an ESP32-P4 desktop robot from OSHWHub team ‘粒子微动’, whose listed members are huochaigun and coucou. Two round 1.28-inch displays form its expressive eyes. Geared motors drive the tracks, while two servos add body movement. Touch sensors let it react when handled. Its Xiaozhi-based software supports voice conversations and camera-assisted image recognition. Browser controls and a supported Bluetooth gamepad provide other ways to operate it. Firmware version 2.2.3 also adds a browser tool for drawing custom eye expressions. The creators cite Doly as the visual inspiration, with redesigned electronics and software. The project page provides build instructions, printable enclosure files, circuit documents and firmware. The build guide calls for a preassembled mainboard, and the published materials carry noncommercial-use terms. Project: oshwhub.com/team_cdvqlfce/pr… #ESP32 #Robotics #DIYElectronics #3DPrinting #DesktopRobot #MakerProjects

KX3 panadapter update: custom PCB, printed housing and a 500 mW WSPR test The KX3 panadapter project now has its custom PCB and a 3D-printed housing. The housing attaches to the back of the M5Stack Tab5, keeping the interface board and touchscreen together in one compact assembly. The custom board combines the ESP32-S3 audio and CAT interfaces with DTR/RTS lines for PTT control and CW keying. It also includes an interface for XPA125B amplifier control. The connections remain accessible through the housing. Tonight’s test was WSPR on 40 metres, with the KX3 transmitting at 500 mW—half a watt. The reception map shows the signal being reported in Australia and New Zealand. #HamRadio #KX3 #Panadapter #M5Stack #ESP32 #WSPR #QRP #DIYElectronics #3DPrinting

Spend too long scrolling, and this little desk pet gets sick. PolyMO is a newly published DIY project built around an ESP32-S3 board with a small AMOLED screen, microphone and speaker. It connects to an Android phone over Bluetooth, and its health responds to time spent in selected apps. Keep neglecting it, and the pet can eventually die. It also talks. The phone handles speech recognition, generates replies and turns them into speech—all locally, without a cloud service. The ESP32 runs the pet’s hunger, happiness and growth. The project includes firmware, Android app source code and 3D-printable enclosure files. Builders need to supply their own speech and language models. GitHub: github.com/brenpoly/polymo

Route 66’s centennial is being marked on the amateur-radio bands Route 66 On the Air is now under way, putting special-event stations on the air from communities connected with America’s historic “Mother Road.” The 2026 event runs from 0001 UTC on September 12 until 2359 UTC on September 20. This year’s operation also marks the 100th anniversary of Route 66, which was established in 1926 and originally connected Chicago with Santa Monica. A network of special callsigns beginning with W6 is representing cities and locations along the route. These include Santa Monica, Los Angeles, San Bernardino, Albuquerque, Amarillo, Oklahoma City, Tulsa, St. Louis and Chicago, along with several mobile and rover stations. Operators can look for the stations on CW, SSB and digital modes. The published frequency guide suggests activity near 14.033 MHz for 20-metre CW, 14.266 MHz for SSB and 14.074 MHz for digital operation. Frequencies may move because of band conditions, interference or other activity. The event is sponsored by the Citrus Belt Amateur Radio Club in San Bernardino, California. Individual stations set their own operating schedules, so not every callsign will be active throughout the full nine-day event. Route 66 On the Air has connected amateur radio with the road’s history for more than two decades. The centennial edition gives operators around the world another chance to contact stations spread along the route from California to Illinois. Official event information: w6jbt.org/route-66-on-the-ai…

DiY599’s LiNK500MP Mk2 brings wireless audio and radio control to the Lab599 TX500MP, cutting down on cables between the radio and a computer for digital-mode operation. The add-on combines a USB audio interface, packet-radio TNC, Bluetooth, GPS and an APRS tracker in an aluminum case that mounts directly to the radio. According to DiY599, it works with software including WSJT-X, JS8Call, VARA and VarAC. The Mk2 also supports compatible Bluetooth headsets. DiY599 currently lists it at €649 including tax, though it’s marked sold out. PileupDX lists it at €679 on backorder. Those prices are for the accessory; the radio is separate. I think, as a radio accessory, t’s too too too expensive.

New project started again, one by one, endless.... This one is a 3S 18650 battery pack for QRP radio operation. I would like to build a compact rechargeable battery pack that can provide a practical field power source for small HF/VHF QRP radios. The pack uses three 18650 lithium cells in series, giving a full-charge voltage of about 12.6 V, which matches the external DC input range of many portable radios. The target output is 12.6 V / 5 A max, enough for most QRP transceivers during receive and moderate-power transmit operation. It is intended for radios such as FT-817/818-style portable rigs, IC-705-type setups with suitable input limits, small CW transceivers, and other field radios that can accept a 3S lithium pack voltage. The board includes the battery holder, protection circuit, charging input, power switching, status indication, and output connector area in one module. T Main design goals: - 3S 18650 battery pack - 12.6 V fully charged output - 5 A maximum output target - Suitable for QRP radio field operation - Built-in protection and charging circuit - Compact PCB module - Clear power and charge indicators - Practical output connector for radio useNew project started again, one by one, endless.... This one is a 3S 18650 battery pack for QRP radio operation. I would like to build a compact rechargeable battery pack that can provide a practical field power source for small HF/VHF QRP radios. The pack uses three 18650 lithium cells in series, giving a full-charge voltage of about 12.6 V, which matches the external DC input range of many portable radios. The target output is 12.6 V / 5 A max, enough for most QRP transceivers during receive and moderate-power transmit operation. It is intended for radios such as FT-817/818-style portable rigs, IC-705-type setups with suitable input limits, small CW transceivers, and other field radios that can accept a 3S lithium pack voltage. The board includes the battery holder, protection circuit, charging input, power switching, status indication, and output connector area in one module. T Main design goals:New project started again, one by one, endless.... This one is a 3S 18650 battery pack for QRP radio operation. I would like to build a compact rechargeable battery pack that can provide a practical field power source for small HF/VHF QRP radios. The pack uses three 18650 lithium cells in series, giving a full-charge voltage of about 12.6 V, which matches the external DC input range of many portable radios. The target output is 12.6 V / 5 A max, enough for most QRP transceivers during receive and moderate-power transmit operation. It is intended for radios such as FT-817/818-style portable rigs, IC-705-type setups with suitable input limits, small CW transceivers, and other field radios that can accept a 3S lithium pack voltage. The board includes the battery holder, protection circuit, charging input, power switching, status indication, and output connector area in one module. Main design goals: - 3S 18650 battery pack - 12.6 V fully charged output - 5 A maximum output target - Suitable for QRP radio field operation - Built-in protection and charging circuit - Compact PCB module - Clear power and charge indicators - Practical output connector for radio use - 3S 18650 battery pack - 12.6 V fully charged output - 5 A maximum output target - Suitable for QRP radio field operation - Built-in protection and charging circuit - Compact PCB module - Clear power and charge indicators - Practical output connector for radio use

Took my refurbished SatNOGS rotator out for its first real satellite contacts—and it worked! I made two contacts with stations in Japan via SO-50 and RS-44. This was the first time I’d put the rotator to use on the air since refurbishing it. Two contacts in the log, and the rotator has now passed its first field test.

I can copy some Morse code by ear, but sending with a straight key or CW paddle is still a challenge. That gave me an idea: why not use a Bluetooth keyboard? So I built a device that takes text from a connected BLE keyboard and sends it as Morse code. I type what I want to say, and the device handles the dots, dashes, and timing. It’s been a big help during CW contacts. I can focus on following the exchange and putting together my reply, without struggling to send it by hand.

An Arduino that can tell a jab from an uppercut? 🥊 Maker Manivannan built a boxing band using an Arduino Nesso N1, its built-in motion sensor, and an added pulse sensor. He trained a model with Edge Impulse to recognise jabs, hooks and uppercuts. The band tracks those movements alongside heart rate, with live feedback on the screen. It even changes the display colour as your heart rate changes. The project combines punch recognition and heart-rate tracking in one wearable. It provides live feedback during training and logs the data for review afterward. Project featured by Arduino on September 9: blog.arduino.cc/2026/09/09/t…

Here’s a small Scottish church with a big connection to radio. 📻 People in Parton are raising money to buy Parton Kirk, where James Clerk Maxwell attended church and is buried in the churchyard. Their idea is to turn it into a science and community centre—a place for talks, workshops and school visits that help people get to know Maxwell and his work. For anyone who enjoys radio, there’s a reason to care. Maxwell’s work connected electricity, magnetism and light, laying the groundwork for our understanding of radio waves. The community has until November 1, 2026 to secure the building. The fundraising target is £70,000: £50,000 for the purchase and £20,000 for insurance and immediate repairs. The full conversion would come later. Campaign and details: justgiving.com/crowdfunding/… ITV report: itv.com/news/border/2026-09-…

M17 has some interesting things going on. If you haven’t followed it, M17 is an open digital voice and data project built by hams, for hams—with hardware and software people can study, change and build themselves. The latest update, posted September 5, is about where the protocol goes next. Developers are discussing a V3 proposal that makes room for new features, alongside an alternative aimed at keeping existing equipment working. It’s still a discussion, so don’t regard this as “V3 has launched.” On the radio side, work continues on bringing M17 to the Retevis C62 through OpenRTX, with the goal of needing only a firmware change. The Linux-based LinHT handheld is moving along too, though it’s still a project for people comfortable with testing and tinkering. Have you tried M17 yet? m17project.org/2026/09/05/th…

Looking for a weekend antenna project? Here are four VHF/UHF ideas worth a look. • A small 70cm Yagi when you want to point toward a particular station: vu3dxr.in/3-element-yag… • A VHF Super J-pole for coverage around you without turning an antenna: vu3dxr.in/vhf-collinear… • A 435MHz collinear for a bigger build. This page credits LZ1DJ’s adaptation of the Diamond BC-200: lz2zk.bfra.bg/antennas/… • A roll-up dual-band J-pole for your bag. Ed Fong’s original QST article gives a documented design for 2m and 70cm: arrl.org/files/file/Tec… The first two links match the shared plans, though I couldn’t confirm who originally drew them. For the roll-up antenna, I’ve linked Ed Fong’s design instead—the article accompanying the shared drawing has a units error. Pick one that fits how you use your radio, then check and tune it before heading out. Which one would you build?

Two telescopic whips, a PVC tee, and a little workshop ingenuity. This DIY 50MHz antenna uses plumbing fittings to house the feedpoint and support two telescopic elements—a neat approach to a horizontal dipole for the 6m band. The adjustable whips are good, you collapse them for storage, extend them for operating, and fine-tune their length while checking SWR. At 50MHz, a typical half-wave dipole starts around 2.85m tip to tip. The final dimensions depend on the actual construction, so measuring matters more than copying a length. Have you built an antenna from hardware-store parts?

Just printed two front panels for ADX-plus with openings for buttons, OLED, and RF ports, and now the enclosure is almost done. The ADX-plus board is already inside the aluminum case, with the 3S 18650 battery pack sitting above it. The front panel carries the OLED window, four buttons, the LED, and the RF port openings. The OLED module is mounted on the back of the printed panel, so the front side stays clean. I also tested it with FT8CN in the video. The phone connects to the radio by USB, and the ADX-plus works with FT8CN directly. This is one of the things I wanted from this build. A small portable digital-mode radio that can run from a phone, without carrying a laptop. There may still be small mechanical details to clean up, but the basic radio, case, front panel, battery pack, OLED, buttons, and FT8CN test are now together. It’s almost done. The only thing left is the code, it still needs polishing by clean up the unnecessary parts, and improve the stability of CAT control. #hamradio #QRP #ADX #FT8 #FT8CN #JS8Call #WSPR #3Dprinting #OpenSourceHardware

I wrote up my old ADX-Plus project: a homebuilt portable HF digital-mode radio based on the ADX / ADX-S idea. The goal was simple: fewer loose boxes and cables for FT8. So ADX-Plus puts the useful parts into one radio: USB-C input onboard USB hub CM108 USB audio CH340C CAT control ATmega328 control Si5351 CD2003 receiver with 455 kHz IF filter relay-switched 40/20/15/10m filters 3S 18650 battery board inside the case In the demo, it connects to a phone by USB and FT8CN decodes signals on 15m. It still needs firmware cleanup and more CAT stability testing, but the hardware idea is already there: a small digital-mode HF station that can work with a phone instead of a laptop. Read the article here: x.com/radhive_fun/status/209… #ADXPlus #HamRadio #HomebrewRadio #FT8 #FT8CN #DigitalModes #PortableHamRadio #Arduino

Introduce ADX-Plus project. It's an arduino based digital-mode transceiver. The project originally comes from WB2CBA, BD6CR improved it and named it as ADS (superhet), and this is my version an upgrade from ADS. I name it as ADX-Plus.

XPA-125B adapter update: Elecraft KX3 support is finally working. This small interface started from my own need. I have several QRP radios here, including IC-705, Hermes-Lite 2, and Elecraft KX3, and I want one adapter to talk to the Xiegu XPA-125B amplifier without changing the amplifier-side wiring every time. For the KX3, the connection is a little different from the other radios. The interface needs to connect to both ACC1 and ACC2 on the KX3. The connection from the interface to the XPA-125B stays unchanged. On the amplifier side, nothing changes. On the radio side, the adapter reads the KX3 control information and sends the proper band voltage and PTT signal to the XPA-125B. So now the same adapter can support IC-705, Hermes-Lite 2, and KX3. It is getting much closer to the small box I wanted from the beginning. It’s one interface between my QRP radios and the amplifier, instead of checking band settings and switching things by hand. #hamradio #XPA125B #KX3 #IC705 #HermesLite2 #QRP #ESP32 #OpenSourceHardware

Summer fading doesn’t mean the end of VHF surprises. Settled weather can create temperature inversions and sharp moisture gradients that guide radio signals far beyond the horizon. It’s called tropospheric ducting, and under the right conditions, stations hundreds of kilometres away can appear on 2m and 70cm. Autumn is a good excuse to start listening—but watch the weather, not just the calendar. Check distant beacons, look for unusually strong signals, and follow your local band plan before calling. There’s something wonderful about hearing a faraway callsign on a band you usually think of as local. What’s your best tropo contact? Source: arrl.org/arrlletterissue

Some VHF/UHF antenna designs. 1. Broadband VHF Avia antenna This antenna is modified by RW4HVN. It is aimed at a wide VHF range, roughly 110–150 MHz. The drawing shows SWR below 1.75:1 across the range, and about 1:1 at 145 MHz. Several ferrite rings are placed near the coax feed point to reduce common-mode current on the feed line. 2. 144/430 MHz square loop antenna This is a dual-band square loop for 2m and 70cm. The large square loop covers the 144 MHz band, and the short added elements near the feed point help tune the antenna around 430–435 MHz. It can be made from copper wire or small metal tubing, and the structure is compact enough for indoor, balcony, or small outdoor installation. 3. VHF/UHF butterfly antenna This antenna is also known as a double-square antenna, double-quad antenna, or butterfly antenna. It uses two square loops connected around the feed point. The article gives about 51 cm per side for the 2m band, and about 17.3 cm per side for the 70cm band. The feed point is placed around the crossing area, with a small gap. The symmetrical structure helps the antenna work without extra matching parts in the shown design. 4. RW4HFN 145/430 MHz dual-band antenna This is a compact dual-band antenna for 145 MHz and 430 MHz. The drawing uses 6 mm metal tube or rod, with ferrite rings placed on the coax near the feed point. The key part of this design is the current path around the feed point. The antenna uses a compact structure to work on both 2m and 70cm, while the ferrite rings help keep RF current off the outside of the coax shield. 5. Coaxial sleeve antenna The last visible section starts to introduce a sleeve antenna made with coax. In this style of antenna, the radiating element and sleeve form the antenna structure, and the feed cable is part of the mechanical build. The screenshot does not show the full section, so the exact dimensions are not included here. These drawings are useful as starting points, not final dimensions to copy directly. Target frequency, wire or tube diameter, feed cable, nearby wall, balcony rail, and mounting height can all change the result. Build it, measure it, trim it. #hamradio #antenna #VHF #UHF #2m #70cm #DIY #PortableRadio