Friday, November 22, 2013
During my work on my Master's degree, I was extremely fortunate to have access to a complete machine shop and foundry through the school. The students there can take a "Materials and Processes" course that teaches the rudiments of welding , lathe and vertical mill, metal forging and casting. I actually obtained special permission to take this undergraduate level course as an elective during my last semester of graduate work. As soon as I complete this post, I will be uploading a video I took of an actual pour to my YouTube site.
Below is a photo of the C-clamp I machined into a finished project from a casting I also made.
Here is the direct linkto the video:
And here is the link to my main YouTube site:
Along with this blog, I now have a companion video site called "Karl's Lab Report" on YouTube. You can find it here:
I plan to post various technical, how-to, and other videos to the site that I feel will be of interest to my viewership.
Please stay tuned for more details.
I plan to post various technical, how-to, and other videos to the site that I feel will be of interest to my viewership.
Please stay tuned for more details.
Saturday, November 16, 2013
I built this about 27 years ago to receive international shortwave broadcasts through a car AM radio. This circuit tunes the 9.5 to 10 MHz and 12 - 12.5 MHz shortwave bands. Back in the day I would listen to the BBC World Service, Radio Canada, Radio Moscow, Deutsche Welle, Radio Australia, and many others. Radio France gave excellent reports on the radiation cloud that rolled across Europe from the Chernobyl mishap in 1986. Several times daily, they would read off a list of all the major cities in Europe, along with the radiation levels in each one. I was "glued" to my radio following the progress of this. The information was of good enough detail and quality one could actually plot it on a map, graphically monitoring the progress of the situation.
The VFO and mixer circuits were taken from the 1979 issue of the ARRL Radio Amateur's Handbook. I built them from the publshed schematics, then tweaked some of the component values for better performance. The VFO coils are wound on glass 3AG fuses that had their elements removed. I heated the end caps with a soldering iron, removed them, took out the fusable element, and glued the caps back on. Then I wound the coils using #28 magnet wire, using the metal caps to solder the wires onto. I used Bohning "Fletchtite" archery glue to secure the windings so they wouldn't move. The variable capacitors were very old, surplus units bought I-can't-remember-where. Looking at the left-hand-side of the photo: The control on the left-hand front of the box is the band selector switch. Next to that is a variable capacitor used to tune in stations. On the rear of the box (in the right-hand-side of the photo) there is a solitary variable capacitor used to tune the antenna for whichever band one is listening to. The whole unit is built in modular form - the VFO has its own board and the mixer is on a separate board. This allowed me to develop and refine the system one module at a time. The VFO is built using "ugly" or "dead-bug" type construction. Its circuit board was made by scoring a copper-clad circuit board with a knife into a grid pattern. The mixer board was actually laid out, then etched using ferric chloride solution.
After many years of sitting unused in an RV, being subjected to all kinds of temperature extremes and even a roof leak, this little device still works. Not only does it still work, the tuning has held calibraton!!! It is within 5 or so KHz of where it was when built. This attests to the quality of the components I used to build it, as electronic components generally drift in value with age.
If I can ever find the original schematic I drew, I'll post it in a future blog entry.
Within the past several years, I have heard China Radio International, Radio Australia, various Spanish-speaking stations, etc. on this unit. Regrettably, the BBC has gotten away from broadcasting quality news programming on shortwave, instead focusing on satelite broadcasts aimed at various target audiences - telling them either what they want to hear or whatever the Powers That Be WANT folks to hear.
To use the converter, simply tune the car radio to an empty spot on the AM dial between 1.40 and 1.55 MHz. Connect the converter between the external antenna and the antenna input on the radio. The converter runs on the car's 12 volt supply; an internal zener diode regulates the supply voltage for the circuit to 9 volts. Use the band selector switch to choose the band to listen to. Reach around the back of the box and turn the peaking control for maximum signal. Then simply tune the right-hand front panel control to tune around for a station. The lower band - the 9.5-10 MHz band, offers the WWV time station from Ft. Collins, Colorado. These WWV signals are very useful not only for checking your watch, but also the RF and audio signals provided are extremely accurate and may be used for equipment calibration. WWV may be heard on 5, 10, 15, and 20 MHz - these broadcasts are done around the clock, 365 days a year. Again I mention those because they are an excellent way of checking the calibration and even the operation of a shortwave radio. Basically, if you can't hear WWV, you will likely NOT hear much else, either.
Soon, in a future post I will delve into the features to look for when buying a shortwave receiver and what to listen for on your radio.
Had today off and decided to head out to the woods. Lord knows I have enough chores and projects to last me a decade, but I used the time to take care of myself. When I go to the lake, I often see a blue heron at the Southeastern shore. Today, it stayed put long enough for me to shoot this picture through the dense undergrowth along the shore. He's well cammoflaged, but I still thought this was a dramatic shot in its own way.
You can double-click on the photo to enlarge it.
Hope you enjoyed seeing this as much as I did today :)
Monday, November 11, 2013
I have been involved with amateur, a.k.a. 'ham' radio for many years. One aspect of amateur radio that doesn't get nearly enough public attention is its continued use during emergencies. People assume that cell phones will always be available, even if land lines and Internet access are out of commission. Depending on what the emergency is, this is sometimes the case. Often, however, the cell towers are damaged by the same event that impacted the rest of the infrastructure. Earthquakes, hurricanes, tornadoes, and fires are but a few situations that could knock out cell phone service in an area. Then there's the spectre of a total failure of the US power grid - which would cause nearly ALL other infrastructure to fail within hours or a couple days, depending on how long it takes for backup generators to run out of fuel or batteries to become depleted. Even the Feds are taking this seriously - See the following article for details:
I was not active with 'ham' radio for a number of years, but since volunteering with a local group of civilian emergency responders, and also seeing the condition the world in general is in, I decided to dust off my old equipment and get back into the fray.
There are amateur radio frequency bands in the "HF' spectrum - that area above AM broadcast and below about 30 MHz; as well as other bands in the VHF - between 30 MHz and 300 MHz; iand in UHF - between 300 MHz and 1 GHz; and even in the microwave spectrum - between 1 GHz and 300 GHz. While there are uses for HF radios during emergencies, the discussion here will be limited to the 2-meter VHF and 70-cm UHF bands.
Both 2-meter and 70-cm band hand-held radios are used extensively for portable and emergency communications. The 2-meter band covers VHF between 144-148 MHz, while in the United States the 70-cm band covers UHF between 420-450 MHz. In Canada, the band is restricted to 430-450MHz. Both of these make extensive use of repeaters - radio stations that receive the low power signal from the portable radio and re-transmit that signal at higher power, on a slightly different frequency, so that the range is greatly extended. A repeater may be located on a tall building or a mountaintop to provide "line of sight" coverage over a large area. Amateur radio repeaters are generally owned by an amateur radio club. These may be either "open access" - available to nearly anyone, or "closed" - meaning restricted to members of the club which owns and maintains the machine.
All of that said, these hand-held radios may also operate without the use of a repeater in "simplex mode", meaning they can "talk" directly to each other if within range.
These radios offer compact size, light weight, and low power consumption - all of which are vital during a civil emergency. With the advent of small, relatively cheap solar panels, many amateurs now use solar power to recharge batteries or even operate their stations directly. Range varies widely depending on the local terrain, how much power the radio puts out, what kind and height the antenna is, etc and can vary from a couple miles to as much as 50 miles if working through a repeater.
The radio in the above picture is a 2-meter radio I have owned for about 20 years. My apologies for the relatively poor image quality; the lighting was not good and furthermore my photographic tripod has gone missing. The 2-meter band, as mentioned above, covers from 144-148 MHz. Radio Shack sold these, as well as a 440 MHz version, for several years during the 1990s. I was lucky to get one before they quit carrying them. I picked 2-meters because this was the most popular VHF band at the time and there were a couple active 2-meter repeater clubs in my area at the time. Indeed 2-meters is still quite heavily used. The object lying next to it is an upgraded telescoping whip antenna I bought separately. The so-called flexible "rubber-duckie" antenna that came with the radio doesn't perform well; the telescoping model is considerably better; an external J-pole or 1/4 wave vertical antenna mounted on a car or house roof is truly the way to go if you want optimum range. This radio has a low power setting of 1.5 watts; on the high power setting can run as much as 5 watts when powered from an external 12 volt supply.
What I Like About This Radio:
1) It has a jack for external 12 volt power right on the top of the radio. This allows one to power it directly from a car battery, solar panel, or other relatively long-lasting source. And by using external power, you realize the full 5 watt output this rig is capable of.
2) The 7.2 volt rechargeable power pack may be taken apart and rebuilt at home; luckily for me since mine is trash after 20 years. There are instructions for doing this online. So unlike many devices, the battery pack is NOT some factory sealed, unserviceable unit that must be thrown away and replaced at high cost.
3) Programming the radio from the keypad is quite easy compared to most units made within the past 10 or so years - and best of all is easily done WITHOUT the use of a computer. Instruction manuals, as well as repair manuals, are still available online. Having something that is easily reprogrammed will be vital during an emergency. You do NOT want to have to drag out a laptop simply to set your radio to talk simplex with someone! This radio amply meets that requirement.
4) It STILL works after 20 years! And that's after sitting around unused for 15 of those. The unit still held in its internal memory the settings for the last repeater I monitored 15 years ago! At some point, the lithium battery that powers the memory will have to be replaced, but there are also instructions online for doing that.
5) Unlike today's handi-talkie radios, this one does NOT try to be all things to all people. It does one thing - 2-meter FM communications - and does it really well.
6) It's got an honest-to-gosh BNC connector on top for the antenna. NO weird adaptors needed to mount different antennas here, unlike what I've read about some of the newer import models!
What I Don't Like About This Radio:
1) Some parts are no longer available - including some of the transistors used in the RF section. So if these fail or get damaged due to hard use, you're pretty much done with it.
2) Battery life - is short. Keep more than one extra battery pack with you if you will be using it heavily where you might not have external power handy. Fortunately these radios came with a separate battery pack you could load with alkaline or other rechargeable batteries. I'd keep that loaded with the new nickel/metal hydride type units.
3) These units ARE bulky by today's standards. Today's hand-helds are not much larger than a cell phone. That said, this is both a blessing and a curse. While compactness is great, it also means tiny little pushbuttons on the keypad. At least with the bulkier older radio, someone with man-sized fingers and hands can operate the keypad WITHOUT mashing several keys at once.
4) No product support available now. As with everything Radio Shack sells, once they decide to do away with the product line, there's no more support when things go wrong. Such is indeed the case here :(
A Couple Quick Notes About Amateur Radio
You DO need a license to TRANSMIT on the 'ham' bands.
But ANYONE, even without a license, may LISTEN IN - and this could be a real asset during any sort of emergency. While official news sources may be keeping quiet "so people don't panic", etc., 'hams' and even CB'ers likely will be talking about what they are seeing and hearing. Granted, one needs to take whatever one hears "with a shaker of salt", but 'ham' and shortwave radio could still once again become a primary source of news "from the outside".
With the near elimination of the morse code requirement, if one is willing and able to learn some basic electronics, as well as the rules and regulations governing amateur radio, it is NOT difficult to get a license these days. Unlike a couple decades ago on back, exams are no longer administered by an FCC employee in an office located downtown in a major city; most local 'ham' clubs offer classes and have volunteer examiners who can help you learn what you need to know and administer the written test.
Through eBay and local ham radio clubs, one can buy gently used equipment at reasonable prices. If one needs a portable hand-held 2-meter or 70-cm radio and is short on funds, they can pick up a radio like mine for around $50 used. One can also look into the new Chinese import brands such as Baofeng and Wouxun. While these are probably NOT built like Kenwood, Icom, Yaesu, etc., you cannot beat them for the money. Indeed, one can buy a dual-band Baofeng handi-talkie for about $50 - or roughly what my HTX-202 might sell for used. The main complaint I read about the Baofengs is they are quite difficult to program from the keypad; most users do that task using their laptop computer. I would NOT like that aspect of it if I needed to program in another frequency during an emergency.
Once a person has a license and some equipment, they not only will have a powerful resource during emergencies, but also have access to the many fascinating aspects of this hobby.
Given the very real inflation in food prices (which the main stream media and government continue to insist isn't happening), I have been looking for ways to grow vegetables into the late Fall and Winter season to augment my groceries and save money. As I was researching materials and techniques for building a small greenhouse to extend the growing season, I came upon this interesting site:
Granted, this thing is MUCH larger than what I need at present. But the design may be scaled up or down, and has numerous advantages of structural regidity and good performance in windy locations. It would be ideal for long term camping or even as expedient housing in an emergency. The parent site, http://diyready.com, has some good links for other do-yourself projects as well.