Track maintenance vehicle on Durango and Silverton Narrow Gauge Railroad. Silverton, Colorado. Little one-man vehicle that had to be manhandled off the track onto the side track.
Video taken on Wednesday, 24 Sept 2014, in Silverton, Colorado. I used my iPhone 5S and did the post-production in CyberLink PowerDirector 12.
Frank Dambach, KK6GPI, asked for a detailed, worked-through example of determining the resonant frequency of an RLC circuit. He chose Extra question E5A16. The question has to do with determining the resonant frequency of a parallel RLC circuit for R=33 ohms, L=50 microhenries, and C=10 picofarads.
The 33 ohm resistor in the question is extraneous information. It’s what in my engineering student days we called “the dimensions of the doorknob,” meaning information that has no bearing on the answer. The frequency of resonance is determined solely by the inductor and the capacitor.
However, if we were determining the Q for the circuit, the resistance enters into the equation. But that’s not the task at hand.
(My apologies for the focus issues early in the video. The camera hunts for something at the center of the scene to focus on.)
Colorado fall color! Taken in Ironton Park along US Highway 550, between Ouray and Red Mountain Pass. Yes, this is Exhibit A as to why I live in Colorado! I experimented with a new (to me) tripod with a fluid head: all the pans are video, not still images.
Royalty free music courtesy of SmartSound.
Here’s your video introduction to Section 5.2, Display Devices, in the ARRL Extra Class License Manual for Ham Radio. The section covers LEDs, LCDs, CRTs, and CCDs. Watch the video to see what these acronyms mean!
To return to the list of Amateur Extra Class training videos, click here.
Attribution: I use one photo from Wikimedia Commons (the different LED types). Here’s the attribution: “Verschiedene LEDs” by Afrank99 – Own work. Licensed under CC BY-SA 2.0 via Wikimedia Commons. And, of course, the starfield backdrops are derived from public-domain images from NASA. In addition, since this video series uses the ARRL book as the text, several of the figures in the video are taken from the book, all with specific reference to the figure in the video.
After attending the Montrose Amateur Radio Club‘s Field Day event atop Sunset Mesa in Montrose, Colorado, I jotted down a few things to bring next time. Maybe this list can jog your memory too.
First, and a big one: An adapter so that I can listen to the radio using a headset, while others in the room/trailer/tent with me—the logger, for example—can hear over a speaker or via another headset. I need headphones for sound isolation while I’m operating, but others nearby also need to know what’s going on. Some requirements:
- Plug into the headphone jack of any radio, usually meaning a 1/4-inch or 1/8-inch jack. Many radios do not have “line out,” so some means of adjusting the input level is required.
- A “line in” input if the radio offers line out.
- A built-in speaker of good quality that can handle a couple watts of audio with its own volume control
- Multiple headphone jacks, both 1/4-inch and 1/8-inch, with independent volume controls
- Power options: 12v DC with an Anderson Powerpole, as power distributed this way is often available in the room where the radio is operated. Self-contained batteries would be a nice-to-have, but not essential.
Some other things that I seem to forget every year:
- Folding chairs—there are never enough places to sit down
- My 2-meter handheld (charged) for on-site communications
- Some tissue paper, e.g., Kleenex
- Bigger hat, not just a ball-cap
One thing I’ve brought every year that is very handy is an extra gallon of water in an ice chest. Late June can get quite hot, and ice water is great to have around.
Here’s your video introduction to Section 5.1, Semiconductor Devices, in the ARRL Extra Class License Manual for Ham Radio.
After you’ve reviewed the video and studied the material in the text, you may return to the list of Amateur Extra videos by clicking here.
P.S. The periodic table of elements shown in the video is from Wikipedia. The attribution in the video is not clear.
Here’s the third of three video introductions to Section 4.2, Electrical Principles, in the ARRL Extra Class License Manual for Ham Radio. This video focuses on resonance, Q, and magnetic cores, particularly on resonance. Resonance is the fundamental building block that Mother Nature provides that makes radio possible.
NOTE: Lester Wetherell points out an error: “In your video amateur extra lesson 4.2 part 3 @ ~ 24 minute, made a mistake saying 10 pF = 1 X 10^-12. Just thought you should know. WD4IFU Lester.” In fact, of course 10 pF is 10 x 10^-12 farads, or in engineering notation, 10E-12 farads.
You can return to the list of Amateur Extra videos by clicking here. Please leave a comment if you have comments, concerns, questions, or suggestions.
Here’s your video introduction to the ARRL Extra Class License Manual for Ham Radio, Section 4.2. This is the second of three videos covering this section; this section discusses reactance, or how inductors and capacitors react to alternating current.
If you have questions, comments, concerns, or suggestions, please comment! You can return to the list of Amateur Extra videos by clicking here.
Here’s some summer flowers and waterfalls at Yankee Boy Basin, outside Ouray, Colorado. (1 min, 43 sec)
The music is “Sleepy Jake” by Silent Partner, courtesy the YouTube audio library.
Here’s your video introduction to the ARRL Extra Class License Manual for Ham Radio, Section 4.2, Electrical Principles. I’ve divided this rather lengthy section into three videos, of which this is the first; this video covers fields, energy, and time constants.
After you have watched the video, studied the material in the text (up to but not including the section on Phase Angle), are sure that you understand the answers to the relevant questions from the question pool, click here to return to the list of Amateur Extra videos.
Please leave a comment if you have questions, comments, concerns, or suggestions.