Grid squares and UTC

Two conventions turn up in every log, every digital mode and every award program: the Maidenhead grid locator, and Coordinated Universal Time.

Maidenhead grid squares

A grid locator compresses a latitude and longitude into a few characters, precisely enough for antenna aiming and distance scoring:

• Field — two letters, an 18 × 18 division of the globe in 20° of longitude and 10° of latitude

(EM).

• Square — two digits inside that field, 2° of longitude by 1° of latitude, roughly 70 × 100

miles in the continental US (EM66). This four-character form is what VHF contests and FT8 use.

• Subsquare — two more letters, about 3 × 4 miles (EM66kn). Used for microwave work and

precision aiming.

• Longer forms exist (EM66kn32) and are used for millimeter-wave and rover operations.

Look yours up once and write it on a card by the radio; QRZ.com, several phone applications and the ARRL's grid-square lookup will all convert an address. Grids are how VHF and 6 m contests score (multipliers per grid), how FT8 reports distance, and how the VUCC award counts credit. See VHF and UHF operating and weak signal, scatter and moonbounce.

Do not confuse a grid square with a CQ zone (used by the CQ contests and the WAZ award) or an ITU zone; DX contest exchanges may ask for either.

UTC, and why your log uses it

Amateur radio is worldwide, so a single reference time avoids arguments about whose Tuesday a contact happened on. That reference is UTC, spoken as "zulu" and effectively the same as the old GMT.

• Log date and time in UTC, always. Contest logs, LoTW matches and QSL confirmations are checked

against it, and a contact logged in local time will fail to match.

• The UTC day rolls over at 7 pm Eastern Standard Time — which means an evening contact belongs to

tomorrow's date in the log, the single most common logging error there is.

• Set the shack clock to UTC and leave the wristwatch local; set the logging computer's clock from

an internet time source, because digital modes such as FT8 need to be within a second or two to decode at all.

• Contests, nets and band openings are announced in UTC. "0000Z Saturday" is Friday evening in the

US.

UTC does not observe daylight saving time, so the offset from your local clock changes twice a year even though UTC does not.