Rules
Contest name: WTZC – World Time Zone Challenge
Sponsor: WTZC Committee
Website: wtzc-contest.com
Cabrillo name: WTZC
1. Date & time
WTZC runs every year on the 3rd weekend in April, from 12:00 UTC Saturday to 12:00 UTC Sunday (24 hours), single continuous operating window.
2. Bands & modes
- Bands: 160 m, 80 m, 40 m, 20 m, 15 m, 10 m
- Modes: CW, SSB. (Category “Mixed” = both CW and SSB used.)
- Digital modes: not permitted.
Recommended CQ call: call CQ TZC (or answer stations calling CQ TZC) during the contest.
3. Exchange
RST + OffsetCode
OffsetCode format: HHMM + E/W, or 0000Z for UTC.
0100E= UTC+01:000330W= UTC−03:300000Z= UTC±00:00 (only this “Z” form is valid)
Daylight saving time / summer time: use your standard legal UTC offset at the time of the contest. That means if your local law applies DST/summer time on the contest weekend, you send the DST-adjusted UTC offset (e.g. the UK is typically 0100E during BST in April).
4. QSO rules
- Each station may be worked once per band per mode (one CW + one SSB on the same band are allowed).
- A CW QSO and an SSB QSO with the same station on the same band are not duplicates and both may count (subject to correct exchange).
- If an exchange is busted (invalid offset, not on the official list, or otherwise incorrect): the QSO counts as 0 points and earns no multiplier credit.
5. Scoring
5.1 QSO points
Let Δ be the shortest distance around a 24‑hour clock between your UTC offset and the other station’s UTC offset (in minutes). Then:
QSO points = 1 + floor( Δ / 60 )
Because the shortest 24‑hour distance is used, Δ is always 0–12 hours (0–720 minutes), so points range from 1 to 13.
Examples
| Your offset | Other station | Shortest Δ | Points |
|---|---|---|---|
0000Z | 0300E | 3h | 1 + 3 = 4 |
0530E | 0800E | 2h30m | 1 + floor(2.5) = 3 |
1100E | 1100W | 2h (not 22h) | 1 + 2 = 3 |
1245E | 0345W | 7h30m (not 16h30m) | 1 + 7 = 8 |
5.2 Multipliers
Offsets are multipliers per band. Each unique received OffsetCode on a band counts as 1 multiplier on that band.
5.3 Mirror bonus
For each HHMM where you have worked at least one HHMME and at least one HHMMW anywhere in your log, add +1 bonus multiplier.
0000Z does not participate in mirror pairs.
5.4 Final score
Final score = (total QSO points) × (total band multipliers + mirror bonus multipliers)
6. Entry categories
Operator: Single Operator
Mode: CW / SSB / Mixed
Power:
- QRP: up to 20 W output
- Low: up to 100 W output
- High: above 100 W, up to your licence limit
No Assisted / Unassisted category separation.
7. Assistance, spotting & remote operation
- DX cluster / spotting networks: allowed
- Self-spotting: allowed
- Remote operation: not allowed (transmitter and operator must be co-located at the station’s operating site)
8. Logs
- Format: Cabrillo 3.0 required
- Deadline: within 7 days after contest end
- Submission: web upload form (see Submit Log)
- Penalties (log checking): Not-in-log or busted call → QSO removed and any associated multiplier removed. Busted exchange (offset) → 0 points and no multiplier credit for that QSO.
9. Awards
- Certificates: PDF download
- Plaques: yes (details published each year)
- Special awards: Most Offsets Worked, Best Mirror Hunter, Top score per UTC offset
10. Valid UTC offsets (fixed list)
Only the following offsets are valid for exchange and multipliers:
Map is illustrative. Always use your standard legal UTC offset at the time of the contest (including DST where applicable).
| OffsetCode | Meaning | DXCC examples |
|---|---|---|
1200W | UTC−12:00 | Baker & Howland Is. (KH1) |
1100W | UTC−11:00 | American Samoa (KH8), Niue (ZK2) |
1000W | UTC−10:00 | Hawaii (KH6), French Polynesia (FO) |
0930W | UTC−09:30 | Marquesas Is. (FO/MQ) |
0900W | UTC−09:00 | Alaska (KL7), French Polynesia (FO/Gambier) |
0800W | UTC−08:00 | USA (W6), Canada (VE7) |
0700W | UTC−07:00 | USA (W7), Canada (VE6) |
0600W | UTC−06:00 | USA (W5), Mexico (XE), Guatemala (TG) |
0500W | UTC−05:00 | USA (W4), Canada (VE3/VE2) |
0400W | UTC−04:00 | Puerto Rico (KP4), Venezuela (YV), Barbados (8P) |
0330W | UTC−03:30 | Canada Newfoundland (VO1/VO2) |
0300W | UTC−03:00 | Argentina (LU), Uruguay (CX), Brazil (PY) |
0200W | UTC−02:00 | Fernando de Noronha (PY0F), South Georgia (VP8G) |
0100W | UTC−01:00 | Azores (CU), Cape Verde (D4) |
0000Z | UTC±00:00 | England (G), Portugal (CT), Iceland (TF) |
0100E | UTC+01:00 | Germany (DL), France (F), Italy (I) |
0200E | UTC+02:00 | Romania (YO), Greece (SV), South Africa (ZS) |
0300E | UTC+03:00 | Turkey (TA), Kenya (5Z), European Russia (UA) |
0330E | UTC+03:30 | Iran (EP) |
0400E | UTC+04:00 | UAE (A6), Oman (A4), Georgia (4L) |
0430E | UTC+04:30 | Afghanistan (T6) |
0500E | UTC+05:00 | Pakistan (AP), Uzbekistan (UK) |
0530E | UTC+05:30 | India (VU), Sri Lanka (4S) |
0545E | UTC+05:45 | Nepal (9N) |
0600E | UTC+06:00 | Bangladesh (S2), Bhutan (A5) |
0630E | UTC+06:30 | Myanmar (XZ), Cocos (Keeling) Is. (VK9C) |
0700E | UTC+07:00 | Thailand (HS), Vietnam (3W), Indonesia (YB) |
0800E | UTC+08:00 | China (BY), Singapore (9V), Western Australia (VK6) |
0845E | UTC+08:45 | Australia (VK – Eucla) |
0900E | UTC+09:00 | Japan (JA), Korea (HL) |
0930E | UTC+09:30 | Australia (VK – SA/NT) |
1000E | UTC+10:00 | Papua New Guinea (P2), Eastern Australia (VK) |
1030E | UTC+10:30 | Australia (VK – Lord Howe Is.) |
1100E | UTC+11:00 | New Caledonia (FK), Solomon Is. (H44) |
1200E | UTC+12:00 | New Zealand (ZL), Fiji (3D2) |
1245E | UTC+12:45 | New Zealand (ZL – Chatham Is.) |
1300E | UTC+13:00 | Tonga (A3), Tokelau (ZK3) |
1400E | UTC+14:00 | Kiribati (T31) |