The topbband is rough in Hawaii with everyone else 2800 miles or more away. There can be significantly less thunder crashes much of the time versus the mainland. However we get fishing floats. These are believed to be llegal locator transmitters sending slow CW from top to bottom on the band. They are used by fishermen to relocate their drift nets in the Pacific ocean. They send a CW id and then some long dashes typically. The usual "Call Sign" uses three randomly letters, sometimes with a number mixed in.
160 meters is workable from Hawaii from about 1630 HST in the late afternoon until 0730 HST the next morning in five clearly defined phases. BTW, we do not observe daylight savings time in Hawaii so HST is always GMT - 10 Hours.
Mainland stations might be expected to appear as follows:
Japan Stations might be expected as follows:
Note: JA's cannot operate SSB on 160 and they have a terribly tiny 160 meter CW band, only from 1907.5 Khz. to 1912.5 Khz.
Note: Several companies make HF bandpass filters, including very useful ones for 160 meters. Cable X-perts sells one brand of these filters, for about $40 each.
The Five Phases
There are five clearly defined and understandable topband Hawaii propagation phases:
1. Eastward Greyline Enhancement. Greyline improves Low band propagation across its east/west dimension. This is the first propagation observed as evening approaches. Stations are not remarkable, West coast, but a fair number are workable. One must be careful not to wait too late and miss this important early period of enhanced Eastward 160 meter propagation. It can start well before local evening in the visual sense. CQ Zone 1 is favored in this phase.
2. The Evening Slump. As Greyline east/west enhancement dies and full dark sets in, there is a slump while nighttime conditions develop. This is rare East Coast to Hawaii time, but in general early evening on 160 just sucks.
3. The 1,2,3 AM Peak. From midnight to 0400 is prime time for Hawaii 160. The entire Pacific Basin is available. CQ Zone 3's cascade in, but US stations from CQ Zone 4 and CQ Zone 5 are well represented. Pacific DX is available and the JA window is wide open, tiny though it is (1907.5 to 1912.5 CW only). This phase has a very dramatic peak at 0200 HST when conditions are near optimal for both JA and CA paths east and west. US Stations well inside the California wall, through the Rockies, into the Plains and Mississippi River area are all likely to be open. Stations will jump up out of the noise and then fall back again in a minute or so. If you are only going to work 160 for a single hour, it should be from 01:30 HST to 02:30 HST.
4. The Witching Hour. Before dawn 160 nearly dies. It would be easy to shut off the rig and quit about 0530 HST. Q's are extremely rare, but may be excellent DX if found. This is another rough slump time. Nightime is dying, but morning Greyline has not arrived yet.
5. The Westward Greyline Enhancement. Suddenly 160 comes alive again. For about 90 minutes propagation to the west is enhanced as dawn advances and westward Greyline launching reaches out past Japan to Asiatic Russia and other worthwhile DX. It would be very easy to miss this period and give up during the witching hour. This dies rather abruptly about 0700 HST.
From 0730 to 1630 HST, 160 meters is dead as a doornail unless you can talk a neighbor into firing up his rig.
Much of this could also be said about 80 meters in Hawaii, but with slightly expanded starting and ending times, about an hour and a half on each end. 40 meters is also likely to follow a vaguely similar pattern, being totally dead for non-local communications from about 0900 HST to 1700 HST.