Category Archives: HF

Propagation – A Index and K Index

The Earth’s magnetic field is continuously monitored by a network of magnetometers. These readings are converted into the A and K index values.

The K index is computed once every three hours (eight times a day) and the values can range from 0 to 9, with 0 being inactive, and 9 representing an extreme severe storm condition. The values are quadi-logarithmic.

  • K = 0 Inactive
  • K = 1 Very quiet
  • K = 2 Quiet
  • K = 3 Unsettled
  • K = 4 Active
  • K = 5 Minor storm
  • K = 6 Major storm
  • K = 7 Severe storm
  • K = 8 Very severe storm
  • K = 9 Extremely severe storm

The A index is linear, and is computed from the eight previous K index values. It ranges from 0 (quiet) to 400 (severe storm).

  • A = 0 – 7 Quiet
  • A = 8 – 15 Unsettled
  • A= 8 – 15 Unsettled
  • A = 16 – 29 Active
  • A = 30 – 49 Minor storm
  • A = 50 – 99 Major storm
  • A = 100 – 400 Severe storm

Generally, propagation conditions are best when the A index is 15 or lower, and the K index is 3 or lower.

Besides causing auroral activity, high geomagnetic field conditions can affect the electrons in the ionosphere, reducing the maximum usable frequency (MUF).

 

HF: 60 meter DX operation

It’s heartening to see that our new FT8 mode has enlivened the 60 Meter band DX activity, to the extent that more than a few ops have achieved working over 100 countries in relatively short periods of time, and while using antennas that were originally designed for other bands. The 60m band is hopping in the evenings and very early mornings, here in the USA.

Islands and Countries heard over the last two weeks: TF1 Iceland; about all of Western and Eastern Europe; Several Atlantic Islands; KH6-land; Cyprus; Samoa; EA8 Canary; D44 Cape Verde; EY8 and UK9; Cayman ZF1; KP4 and KG4 Guantanamo and CO’s from Cuba; several stations in Turkey; 3D2 Fiji Islands; The UAE; the Baltic states; HB0 Liechtenstein and LX1 Luxembourg; and South Africa. Others can be found  by  CLICKING HERE

FT8 Cross-Band: For 60m FT8 operations in the USA and Europe, the 60m 5357-kHz channel is the most popular. New Zealand and a few other Pacific stations are found transmitting on the nearby 5363 channel, a channel unauthorized for use in the USA. So, given these restrictions, a few of these Oceanic stations can be worked from the USA via “cross-band” or cross-channel mode. Enjoy the band!

From Mark W2OR