29 September, 2011

Communication with vector potential waves

Field lines (black) and potential (red) for a dipole, static field. 
In QEX July/August 2011 Robert K. Zimmerman (NP4B, VE3RKZ) had an intriguing article entitled "Transmission and Reception of Longitudinally-Polarized Momentum Waves."  What he claims is that he has communicated over a distance of 1500 m at 1296 MHz using vector potential or momentum waves.

Unlike transversal electromagnetic (TEM) waves these are longitudinal waves just like sound waves. This may seem like real magic, but if true it would allow covert communications which is undetectable with ordinary radio receivers and antennas.

01 September, 2011

Elecraft K2 do's and don'ts

In July 2011 Don Wilhelm, W3FPR, suggested that someone ought to write a comprehensive K2 Owner's Manual. This posting does not qualify as one, but at least it lists some things to watch out for regarding the Elecraft K2.
    Minimal stress on the headphone jack
    By all means avoid this situation!  
    • Failing headphone jack: One of the most frequent complaints is the need to replace the headphone jack. Mine has lasted for ten years by being careful not to put undue stress on it. The best thing to do is to use an angled plug for the headphone (left-hand image). Many headphones have that or one can use an extension cord with an angled plug. In either case, this is the best way to minimize the mechanical stress. The worst one can do is surely to put a long mini-jack to jack adapter plug directly into the headphone jack (right-hand image).