Tools
Tools
Handy tools for amateur radio operators. All run locally in your browser — nothing is sent anywhere.
Handy tools for amateur radio operators. All run locally in your browser — nothing is sent anywhere.
Find your Maidenhead grid square. Click anywhere on the map, or tap Use my location for an instant result. Returns 4, 6 and 8 character locators.
Enter a Maidenhead locator to jump to it on the map. Accepts 4, 6 or 8 characters.
The Maidenhead Locator System divides the world into a grid of squares identified by letter and number combinations. A 4-character locator (e.g. JO02) covers a 2°×1° area; a 6-character locator (e.g. JO02nb) narrows it to around 5×2.5 km; an 8-character locator to roughly 500×250 m. It's widely used in amateur radio to describe station locations — especially in VHF/UHF contests, meteor scatter, and satellite work.
Handy calculators for common amateur radio tasks.
Decodes the 3-digit code printed on ceramic capacitors. Example: 104 = 100 nF.
Enter an output or input frequency, pick the standard offset for the band, and the calculator works out the other frequency. All values shown to 4 decimal places.
A repeater transmits and receives on two different frequencies at the same time. The gap between those frequencies is called the offset. A typical 2m repeater uses a 600 kHz offset; 70cm FM repeaters typically use 1.6 MHz.
The output is the frequency the repeater transmits on — what you tune to and listen on. The input is the frequency you transmit on. Your radio needs both programmed, plus the correct CTCSS tone.
If the repeater used the same frequency for both transmit and receive, it would hear its own output and loop continuously. The offset keeps them separate so the repeater can listen and talk simultaneously without interfering with itself.
Element lengths and spacings for common antenna types. All dimensions apply a 0.95 velocity factor — the standard practical correction for wire antennas. Always verify final dimensions on the bench.
Classic centre-fed half-wave dipole. Cut to resonance, feed with 50 Ω or 75 Ω coax.
FrequencyQuarter-wave ground-plane vertical. Radials should be the same length as the element.
FrequencyStandard 3-element Yagi — reflector, driven element and one director. These are starting dimensions; final tuning on the bench is always needed.
FrequencyInspired by hamradiocalculator.com