There was recent documentary called “Mega quake 10.0.” With my apologies to the seismologists here is a little comparison to our more familiar dB scale measurements. In some respects we all live in Earthquake Country not just California. The program described the effects of an earthquake in various magnitudes. Some of the bigger quakes have occurred in the middle of the country such as the “New Madrid Quakes” around 1809 and 1810. They rang church bells in Boston! The presenter tried to explain the earthquake scale using stacked quarters. A magnitude one quake was 1 quarter and magnitude 2 quake was […]
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I have only been a licensed ham operator since August 23, 2011, so most of the history of the hobby comes from what I hear from other hams who have been in the hobby longer than I have. But I have been in the emergency services as a fire fighter and medic for 38 years. I have observed the evolution of the emergency services in America generally and in California specifically over that time. My observations have lead me to think that perhaps The Future of Amateur Radio will be different from its past. Learning about the history of the ham […]
DOWNLOAD FLYER HERE Have you ever wondered what Ham Radio is all about? Come to this FREE Saturday workshop to learn about Ham Radio. See demonstrations and equipment, talk to local Hams, see what you will need to learn to get your own license, You can even talk to other Hams on our radios, take practice examinations using the FCC questions and take the FCC exam if you want. Self-paced study guides will be available for $23 if you want to learn more and study for the FCC test. Workshop Agenda: Why Ham radio? (when all else fails, radio works) Radio […]
By Jim, N6TP The recent interest in WLW (500 Kw in the 1930s) reminded me of the technology that went into producing a good quality high level plate modulated transmitted signal. You may remember prior to rule change of 30 years or so by the FCC that the maximum power limit (where licensed) was 1,000 watts input. This meant that if you were running high level plate modulation, you had to have 500 watts of RMS audio power for 100% modulation. You will recall that the secondary of the modulation transformer was in series of the B+ to the final tube(s). […]
Decibels: Pesky Little Critters In our telecommunication careers, we may have all used dBs in our work. Here is a little background and how we use them in amateur radio. Decibels are a form of mathematical shorthand using logarithms. Logarithms probably originated with the ancient Greeks. Logarithms have the property expressing large values or ratios in more easily understood human terms. Decibels originated when the engineering of analog telephone circuit became more complicated. The Bell System of fond memory in the 1920’s needed a way to design telephone circuits taking into account cable and component losses plus the gain of amplifiers. One […]
By Jim, N6TP, n6tp@arrl.net We are familiar with the formula for a half-wave dipole. It appears in the antenna handbooks and in various test questions for amateur radio license exams. It goes like this. Divide the operating frequency in MHz into “468” and the answer comes out in feet. For example: 468 divided by 7.150 MHz equals 65.5 feet! If we do a little rounding, we will cut our half-wave dipole to 65 feet 4 inches. Let’s look a half-wave dipole. As the name implies it is a half-wave antenna resonant at its operating frequency. We choose to make it a half-wave dipole as […]