Directional antennas, multi-mode digital voice, and lousy propagation

Stories you’ll find in our February, 2019 edition:

The Development of the Directional AM Broadcast Antenna
By John Schneider W9FGH

In the early years of AM radio broadcasting, all stations utilized non-directional antennas made of wire and suspended between towers or buildings. Interference, especially at night was severe—enough to disrupt reception of the desired station—and if the frequencies of the two stations were slightly separated, there would be a heterodyne beat note. As a result, only a few widely spaced stations could operate on each of the AM broadcast channels in the entire country at night—many of which shared time on a single frequency. As antenna technologies were developed and improved in the early 1930s, a few progressive stations began experimenting with multi-element directional arrays. John gets into the details of those early experiments that led the way to today’s AM antenna arrays.

TSM Reviews: Jumbo MMDVM Hotspot
By Mark Haverstock W8MSH

Over the last few years, several hotspot interfaces have appeared on the market such as DV Mega with Raspberry Pi, DVMega with Bluestack, Shark RF OpenSpot, and DV4Mini—all hovering around the $200+ range, making them a bit pricey for all but the most dedicated digital radio users. However, a new wave of digital hot spot, manufactured in China, are finding their way onto eBay, Amazon, and other online sites. These Multi Mode Digital Voice Modem (MMDVM) boards are not developed to replace repeaters, but rather to supplement them. In areas where there is no repeater, a hotspot lets a user connect directly to a digital network via the Internet. In areas of heavy repeater use, a hotspot allows the user to access the digital network without competing for an available time slot. Mark tells us how all of this works in actuality.

Piggy Bank Ham Radio: Part 3
By Cory GB Sickles

In the third installment of his Piggy Bank Ham Radio series, Cory explains the concept of literally saving pennies for cheap adventures on the ham bands that can have much bigger payoffs. His advice includes how to assemble the most useful tools at the best possible price; how to improve your soldering skills to repair older equipment that may need only a small amount of work to be useful again; making use of off-the-shelf technology you may already have to further your amateur radio activities. Cory provides good advice for new hams and veterans of the bands alike who want to spend more time on the air and less time looking through online catalogs and wishing they were.

The Discoveries of Hans Christian Ørsted
By Georg Wiessala

The Great Danish scientist, Hans Christian Ørsted, was a pioneer of electromagnetism who paved the way for Michael Faraday (1791-1867), Bohr and others. With his brother, Anders Sandøe Ørsted (1778-1860, who became a jurist and the third Prime Minister of Denmark), Hans Christian epitomized what has been termed the “Danish Golden Age,” from the turn of the 18th Century to the mid-19th Century. It was he who was said to have coined the word “electromagnetic.” The theoretical world in which Ørsted worked was packed with adherents of opposing philosophies but it was a chance observation that allowed Ørsted to claim an important contribution to the science of electricity.

Scanning America
By Dan Veeneman
First Look: Uniden Bearcat SDS200

Federal Wavelengths
By Chris Parris
Tucson Federal Update and DoE

Milcom
By Larry Van Horn N5FPW
Aircraft Spotting in the Digital Age

Utility Planet
By Hugh Stegman
It’s Time to Expand Aero Band SELCAL

Shortwave Utility Logs
By Mike Chace-Ortiz and Hugh Stegman

Digitally Speaking
By Cory GB Sickles WA3UVV
DV Miscellany

Amateur Radio Insights
By Kirk Kleinschmidt NT0Z
Audio Equalizers—Awesome, Overlooked and Gobbledegooked!

Radio 101
By Ken Reitz KS4ZR
Shortwave Listening in Your Car

Radio Propagation
By Tomas Hood NW7US
Lousy Propagation on 40, 80 and 160 Meters

The World of Shortwave Listening
By Andrew Yoder
Government Shutdown Spurs Pirate Shortwave Activity

The Shortwave Listener
By Fred Waterer
Shortwave Radio Yesterday and Today

Amateur Radio Astronomy
By Stan Nelson KB5VL
Tracking Meteor Activity

Adventures in Radio Restoration
By Rich Post KB8TAD
EICO HF-35: A Williamson-Mullard 520 Audio Amplifier

Antenna Connections
By Dan Farber AC0LW
Stealth: An Ongoing Philosophy

The Spectrum Monitor is available in PDF format which can be read on any desktop, laptop, iPad®, Kindle® Fire, or other device capable of opening a PDF file. Annual subscription is $24. Individual monthly issues are available for $3 each.

Ken Reitz, KS4ZR, is publisher and managing editor of The Spectrum Monitor. Contact him at [email protected].

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