Hamvention® Award Nominations Sought

The Dayton Amateur Radio Association is seeking nominees for the 2019 Hamvention Awards. These are among the most prestigious awards in amateur radio and honor achievements in various aspects of our hobby.  Categories include Amateur of the Year, Technical Achievement, Special Achievement and Club of the Year. 

Nomination deadline is February 15. For more details, visit <http://hamvention.org/event-details/awards/>.

Ohm, My…

We all know what an ampere is, right? According to Ohm's Law, one amp (I) equals one volt divided by one ohm (E/R), or some variation that fits the basic equation. But Ohm's Law defines the relationship between these units, not what defines the units themselves. And those definitions have just changed.

In November, the international body that defines each of these units adopted new definitions, not only for electrical measurements but those for mass (the kilogram), temperature (Kelvin), quantity (mole) and luminosity (candela).  In a statement, the General Conference on Weights and Measures said the new definitions are based on "seven physical constants (for example the speed of light, the Planck constant and the Avogadro constant) and are therefore inherently stable." The goal is to eliminate the need for refining definitions in the future as measurement techniques become more precise. 
 

The need for a change, according to report on the vote in the New York Times, was made evident by "Le Grand K," the platinum-iridium cylinder housed in a vault in Paris that has defined the kilogram since 1889. The problem, it was discovered in 1990, was that somehow, Le Grand K had become 50 micrograms lighter than six official copies. The new definition of the kilogram, 28 years in the making, is based on the mathematical formula known as Planck's constant rather than on a physical object.

The ampere and other electrical units will also be redefined on the basis of Planck's constant, which has been linked by physicists to electrical voltage and resistance, according to the Times. According to the General Conference announcement, the changes will affect only those users who need "the highest level of accuracy," noting that "(f)or the vast majority of measurement users, no action need be taken as the volt will change by about 0.1 parts per million and the ohm will change by even less."

The new definitions take effect on May 20, 2019.

Cycle 25 is On its Way!

November 17, 2018 magnetic map of the Sun
shows two sunspots. The one labeled AR2727
at the lower right is a Cycle 24 sunspot while
the "ephemeral sunspot" at the upper left,
with reversed magnetic polarity,
is from the future Cycle 25.
(NASA Solar Dynamics Observatory
image, via SpaceWeather.com)

Beleaguered DXers, take heart … solar cycle 25 is starting its engine! SpaceWeather.com reports that in mid-November, a small sunspot made a brief appearance in the Sun's northern hemisphere, vanishing a few hours later. What was notable, however, was that its magnetic polarity was reversed from that of the vast majority of Cycle 24 sunspots. That, along with its location far from the Sun's equator, indicates that this "ephemeral sunspot" is an early messenger of Cycle 25. 

According to SpaceWeather.com, this is the third Cycle 25 sunspot observed to date. It points out that it is common for sunspots from different cycles to coexist during the transitions from one cycle to the next, and is generally a process that plays out over the course of a year or two (so Cycle 25 has not yet really started). 

The presence of these early Cycle 25 spots appears to provide reassurance that there will be a Cycle 25, allaying fears that we may be heading for another "Maunder minimum," a lengthy period with virtually no sunspots. "The solar cycle is still operative," notes SpaceWeather.