Whether you are antenna restricted and need something that blends in, or just want to get started building your own antennas, you will find great antenna ideas that you can build yourself inexpensively at the April RRRA Meeting.
Turn your Android phone into a modern ham radio transceiver with this free open source software & hardware project.
kv4p HT is a homebrew VHF radio that makes your phone capable of voice and text communication completely off-grid with at least a Technician class amateur radio license.
The radio simply plugs into the USB C port on your Android smartphone and transforms it into a fully-fledged handheld radio transceiver. It’s completely open source (GPL3): the Android app, ESP32 firmware, PCB designs, and 3D printer files.
It’s small enough to fit in your pocket and take anywhere, and since it has no internal battery it’s the perfect radio to put in a go-bag or your car’s glove compartment.
NOTE: kv4p HT is an open source project you build yourself and has absolutely no warranty, or guarantees on functionality or reliability! 1
ℹ️ Visit the KV4P Quick Start page to get started building your radio.
- Only $35 to build, with 3 components to solder
- 100% ham radio, always completely off-grid
- Crystal-clear 44kHz 8-bit ADC/DAC audio, with filters and squelch
- Texting with notifications just like SMS — radio-based APRS messaging (not just location) with built-in 1200 baud modem
- Scan through unlimited memories and groups
- No battery means nothing to charge except your phone
- 1 watt transmit can go miles yet sips your phone’s battery
- Accessibility options: live closed captions (on supported phones), turn off animations, sticky PTT with haptic feedback 2
“Home page”, KV4P, accessed November 2 2024, https://kv4p.com/. ↩︎
“Home page”, KV4P, accessed November 2 2024, https://kv4p.com/. ↩︎
Along with his usual Field Day antenna supplies, Dale WB6BYU brings along a handy table of wire lengths for each band for the antennas he is most likely to put up. This reference guide eliminates the need to calculate wire lengths in the field and can be easily shared with other operators who need to build an antenna.
W6BYU has published a version of his Field Day antenna length table at the Practical Antennas website
All dimensions are for 1mm (AWG #18) bare wire. In most cases, they should be close enough for other wire sizes likely to be used for portable antennas. There will always be some variation due to how the antenna is constructed, wire insulation type, height above ground, and other factors, but these should give you a good starting point. 1
ℹ️ https://practicalantennas.com/designs/dipole/halfwavedipole/
| frequency MHz | wire length ( one side ) |
|---|---|
| 1.925 | 122 ft |
| 3.55 | 65 ft 6 in |
| 3.9 | 60 ft |
| 7.15 | 33 ft 3 in |
| 14.2 | 17 ft |
| 21.2 | 11 ft 6 in |
| 28.5 | 8 ft 6 in |
| 50.3 | 57.5 in |
| 53 | 55 in |
ℹ️ https://practicalantennas.com/designs/loops/loop-sizes/
| frequency MHz | wire length | short side | long side |
|---|---|---|---|
| 14.2 | 72 ft 6 in | 12 ft | 24 ft 3 in |
| 21.2 | 48 ft 6 in | 8 ft | 16 ft 3 in |
| 28.5 | 36 ft 6 in | 6 ft | 12 ft 3 in |
| 50.3 | 20 ft 7 in | 3 ft 6 in | 6 ft 9.5 in |
ℹ️ https://practicalantennas.com/designs/loops/fd200ohm/
| frequency MHz | wire length | sides | top / bottom | zip cord matching stub |
|---|---|---|---|---|
| 7.15 | 143 ft | 41 ft 4 in | 60 ft | 23 ft 6 in |
| 14.2 | 72 ft | 19 ft 8 in | 32 ft | 12 ft |
| 21.2 | 47 ft 3 in | 12 ft 7 in | 22 ft | 8 ft 3 in |
| 28.5 | 36 ft | 9 ft 8 in | 16 ft 6 in | 6 ft |
| 50.3 | 20 ft 8 in | 5 ft 10 in | 9 ft | 3 ft 6 in |
ℹ️ https://practicalantennas.com/designs/loops/wirequad/
| frequency MHz | driven element wire length | reflector wire length | spacing |
|---|---|---|---|
| 7.15 | 140 ft | 151 ft | 20 ft |
| 14.2 | 70 ft | 73 ft 6 in | 10 ft |
| 21.2 | 47 ft | 50 ft | 6 ft 8 in |
| 28.5 | 34 ft 4 in | 38 ft | 5 ft 6 in |
| 50.3 | 19 ft 9 in | 21 ft 3 in | 3 ft |
ℹ️ https://practicalantennas.com/designs/parasitic/wireyagi/
| frequency MHz | driven element wire length | reflector wire length | spacing |
|---|---|---|---|
| 7.15 | 66 ft 8 in | 69 ft | 20 ft |
| 14.2 | 33 ft 9 in | 34 ft 8 in | 10 ft |
| 21.2 | 22 ft 6 in | 23 ft 3 in | 8 ft |
| 28.5 | 16 ft 8 in | 17 ft 9 in | 6 ft |
“Field Day antenna length table”, Practical Antennas, accessed May 29 2024, https://practicalantennas.com/applications/portable/fieldday/fdwiretable/. ↩︎
These two easy to build Powerpole projects could be a useful addition to your gear bag or go-kit.
They are so simple that no schematic diagram is necessary.
In his A Sensitive Field Strength Meter for Foxhunting article (a free preview from the July 2021 issue of QST Magazine), Woody White, KZ4AK, presents the Field Strength Meter (FSM) for Foxhunting he built based on a design featured in the June 2001 QST article Simple RF-Power Measurement by Les Hayward, W7ZOI, and Bob Larking, W7PUA.
KZ4AK begins with a brief discussion of the W7ZOI/W7PUA digital readout FSM he built. And he quickly arrives at a key design consideration relevant to Foxhunting: “… signal trends are harder to follow on digital readouts than with an analog meter.” 1
His article covers:
KZ4AK’s article references two QST articles about similar FSMs and includes the complete schemetic diagram for his FSM.
“A Sensitive Field Strength Meter for Foxhunting”, ARRL The national association for Amateur Radio, accessed June 17 2021, http://www.arrl.org/files/file/QST/This%20Month%20in%20QST/2021/07%20July%202021/2021-07%20WHITE%20Sensitive%20field%20strength%20meter.pdf. ↩︎
Australian Amateur Radio Operator VK3YE presents a novel audio oscillator design on his YouTube channel. It’s an easy to build, low parts count, project; weatherproofing considerations are left to the builder.
The VK3YE YouTube channel includes videos on QRP amateur radio, simple electronics and antennas.Building a new antenna is a great way to start the new year. The folding J-pole antenna project by RRRA member KA0ZLG , and featured in the March 2005 issue of QST magazine, is a new twist on an old design. It is an excellent cold weather project for improving your Go-Kit or enhancing portable operations.
The QST article (A Backpacker’s Delight—The Folding J-Pole) includes detailed instructions for building this project along with numerous photographs.
Copies of KA0ZLG’s article may be found on-line with a search for folding+j-pole+ka0lzg
Preorder the µBITX QRP HF Transceiver kit (“micro BITX”) for $109 with free India Post shipping; $119 with DHL (1 week) shipping.
Shipping will start after December 25, 2017.
The µBITX is a QRP HF transceiver that you can build. This kit includes:
You must provide an enclosure, power supply, microphone case, and speaker to complete this kit.
The µBITX is a general coverage HF SSB/CW transceiver kit with features you NEED for operating ease, convenience and versatility. It works from 3 MHz to 30 MHz, with up to 10 watts on SSB and CW with a very sensitive receiver. It features digital tuning, dual VFOs, RIT, CW Keyer and more. The µBITX is a general coverage HF SSB/CW transceiver kit with features you demand for operating ease, convenience and versatility. It features digital tuning, dual VFOs, RIT, CW Keyer and more. [ 1 ]
This transceiver, a descendent of the BITX bidirectional 20M SSB QRP transceiver for homebrewers, was announced on March 2, 2017, by Ashhar Farhan (VU2ESE) in the µBITX—A reboot of the old BITX thread in the Groups.io BITX20 group.
Technical specifications are available on the HF Signals µBITX page along with links to:
The uBITX boards are hand-assembled by a collective of women [based in Hyderabad, India]. Each of the toroids is hand wound. This provides these women with livelihood. The assembled boards are then DC checked and a final RF check is performed to check the receiver’s sensitivity as well as transmitter’s output before being shipped. Each board is individually numbered. [ 2 ]
A dummy load is a piece of equipment which allows transmitter testing and adjustment with minimal radiation of RF energy.
Most dummy loads are constructed using non-inductive resistors and utilize various heat sinking methods, ranging from passive air cooling (e.g. Elecraft DL-1, MFJ-261) to submersion in non-conductive oil baths (e.g. Heathkit Cantenna, MFJ-250), to dissipate the transmitter power.
An inexpensive, and easy to assemble, home brew alternative to conventional dummy loads is the K5LXP Saltwater Dummy Load
The article provides construction and alignment instructions along with an network analyzer SWR plot and a graph of thermal performance for 100w input over 30 minutes.
Individuals building this project assume all risk of injury, loss, or property damage.
Rediscover the spirit of home brewing with K9EID’s Pine Board Project.
Pine Board Transmitter Building:: The Pine Board Project begins building 80 and 40 meter AM… https://t.co/qgTAsmOM9Z
— DXER (@kc9ldo) July 16, 2017
