Category Archives: Amateur Radio
Albert Prince spotted the rooftop antenna on a pile of garbage outside a Canarsie home. When he pulled his van over to move the device into the vehicle, he got slapped with a summons for ‘unauthorized removal of residential recyclable material using a motor vehicle’ by sanitation workers and had his van impounded.
One man’s trash is another man’s legal nightmare.
After a two-year battle, a Brooklyn carpenter has beaten a $2,000 ticket for picking up a discarded TV antenna for an art project.
In February 2011, Albert Prince, 56, spotted a rooftop antenna — which can sell brand new for less than $100 — on top of a pile of garbage bags outside a Canarsie home. Prince, a sculptor who belongs to a group called Art by Construction Workers, said in court papers he thought the antenna could be “a very good piece.”
When he pulled over at a nearby store, he was confronted by two sanitation cops. He said he was “kind of perplexed” by their demeanor and they made him feel like he “murdered somebody.”
He was slapped with a summons for “unauthorized removal of residential recyclable material using a motor vehicle,” and his van was impounded. He had to pay the fine to get his van back — plus another $500 to get it out of the impound lot.
Two lower court judges upheld the fine, saying what he did was a clear violation of the city law and they had no leeway to reduce the amount of the fine.
In a decision Tuesday, the state Appellate Division found the fine was so excessive it violated Prince’s constitutional rights. But they refused to refund the $500 in impound fees, finding he would have paid less had he dealt with the matter sooner.
Janet Zaleon of the city law department said the agency was reviewing the decision.
Read more: http://www.nydailynews.com/new-york/brooklyn/artist-avoids-2-000-fine-thrown-away-tv-antenna-article-1.1352343#ixzz2U7wY8WJh
I nearly threw away my worn out Braun 5569 electric shaver a few months ago. On second thought, I decided to at least check it for usable components before I disposed of it. It occurred to me a short while afterwards that it might be fun to attempt to convert whatever was inside it into an amateur radio
I got around to opening it up last week. It was mostly built using surface-mount technology (SMT), but at least it used discrete devices vs. a custom-made IC. A waterproof coating made salvage difficult, but careful surgery with a razor blade allowed me to remove all five SMT transistors and half-a-dozen diodes; one of which was a 5V Zener.
The transistors were soldered to bits of copper-clad “carriers” along with flying leads. One transistor didn’t survive the transplant operation. The one non-SMT transistor, an NPN power device, refused to oscillate above 1MHz. The remaining three NPN and one PNP transistors appeared to function well enough at 14MHz that I thought I’d have a go at building something for 20m.
My first idea was to build this Japanese 10/6m DSB rig for 20m using a 14.3MHz computer crystal from my junk box.
After the standard amount of tinkering the transmitter appeared to be operational. Two of the tiny Silicon diodes taken from my electric razor matched well enough to produce a decent carrier null in the single-balanced modulator. I used a pair of NPNs in a push-pull PA stage. A forward-biased diode taken from the razor was used to set the PA bias. The RF CW output was ~90mW. An electret mic from an old telephone drove the PNP SMT transistor in the AF amplifier. The VXO provided a tuning range of 8kHz.
Unfortunately, switching the transmitter to the direct-conversion receiver mode produced the expected result. The 100kW, Nashville-based, WWCR, on 13.845MHz swamped the amateur phone signals. Placing a “balancing” pot in line with the the SBM diodes helped considerably, but not enough to completely eliminate the interference. Past experience tells me that at my QTH a narrow, triple-resonator, BPF is needed between the antenna and these simple diode mixers. I decided to pull the DSB rig apart and build instead a 20m CW station.
I built a 0V1, common-base, Colpitts autodyne regenerative receiver using two of the NPN SMT transistors. The Q-multiplied RF resonator easily shrugs off interference from the high power commercial shortwave transmitter.
The transmitter begins with a variable quartz crystal-controlled oscillator (VXO) made from the third NPN transistor. The final PNP SMT device was used in a common-base, RF power amplifier (PA). The transmitter VXO tunes from 14.055 to 14.061MHz using an xtal cut for the QRP calling frequency. The oscillator free-runs on transmit; only the PA is keyed. The RF output power is 75mW. A 7th order lowpass filter (LPF) holds the harmonics below -45dBc.
The current draw is 1mA on receive and 12mA on transmit using a 9Vdc battery as my power supply.
The bread-boarded transmitter appears in the above photo. The LPF is on the left-hand side, followed by the PA and quartz-crystal oscillator. Two of the transistors taken from the electric razor can be seen in this photo.
Here’s a close-up of the two-stage receiver. The regenerative detector is on the left-hand side of the board, followed by one stage of audio amplification. The variable capacitor at the left tunes the receiver from 14.000 to 14.075MHz.
I was pleased to have worked four stations with this setup on April 17, 2013.
W4SX GA 569/339 K2 @5W
KB0PCI MN 569/339 12w
KD4ESO AL 579/559 100w
K5EST MO 569/559 5w
Coming up to the house later in the day I found three Reverse Beacon Network receivers had made captures of my 75mW signal. Oddly enough, all three were located in Europe.
On April 18, I worked three stations; my transmitter still driving an end-fed wire antenna with 75mW of RF power.
N0UR MN 449/229
W4SX GA 579/449
F6DCD France 559/519 K2 @ 5W
F6DCD very kindly called again 35 minutes later to inform me that my signal was still audible near Strasbourg. Denis increased my signal report to 529. Needless to say, I was ecstatic to have “crossed the pond” with the transistors taken from my old electric razor.
On 19 April I received an email from F6DCD
I was really pleased to contact you with your 75 mW. I heard you calling on frequency during 1 hour and more. Your sig was really nice on my K2.
By Nyle Steiner K7NS April 2008.
I call this very simple transmitter the “Easy Ten” because it can be easily heard at a distance of 10 miles. Transmitter antenna is a random length wire run through a hole in the wall and thrown into a tree.
The white wire just visible in the upper left is the antenna. The Red clip lead that exits at the upper right is a ground wire connected to the ground screw of an electrical outlet.
Looking toward the transmitter location in a small town that can barely be seen 11.5 miles away. The transmitter could be heard clearly from this location, the top of a hill overlooking a lava field.
Schematic Of Transmitter.
I am not an antenna fanatic and I like to work with the simple stuff, especially when it comes to working with frequencies in the 3.5 and 7 mhz range. Fussing around with coax lines, SWR, baluns and all that fancy stuff does not usually appeal much to me, nor have I found it at all necessary for getting a signal out. A simple random length of wire thrown into a tree works very well if you can simply adjust the transmitter to put a signal into it.
I certainly am not trying to say this is the best way to make antennas. The point that I wish to emphasize is that the simple techniques that I am describing here, do work well and make good respectable antennas. I have made many many contacts across the pacific ocean and across the United States using simple antennas as described here and just one watt of output power. I have almost always been able to make contacts with stations at least two states away from any given antenna setup using just one watt.
A simple homemade level meter can tell you when you have optimized the signal output to the antenna. The signal meter is capacitively coupled to the antenna and reads it’s RF voltage level. A signal level meter can be easily made from a DC microameter and a germanium diode. Connect the germanium diode across the meter with the cathode on the positive side. Then connect one side of the meter to ground and the other side of the meter to a short wire (one or two feet long) that rests near the antenna wire from the transmitter. It does not matter which side of the meter goes where.
With the key down, adjust the 365 pf variable capacitor in the circuit above for a peak reading on the meter. That is all there is to it. With the circuit described above, a big antenna will tend to swamp the oscillator and prevent it from running. The variable capacitor attains the best compromise between swamping the oscillator and having too little of antenna coupling. The picture above shows a fixed capacitor feeding the antenna. A variable capacitor was first used to peak the signal meter and then an equivalent fixed value capacitor was put in it’s place. A capacitor is not necessary at all sometimes with shorter antennas. In this case the antenna can be connected directly to the transistor collector.
This simple meter has worked well on numerous other transmitter projects. This meter can not tell how much power a transmitter is putting out but it is very good for indicating when the transmitter is putting the most signal into the antenna. For a given transmitter, you don’t really need to know how much power it is putting out. You just need to know when the transmitter is putting what it is capable of into the antenna. This meter seems to accomplish that.
With all other conditions remaining the same, the more signal voltage there is on the antenna, the more power the antenna is radiating. It is that simple. Don’t worry about near field and far field theory or any of that stuff. According to theory that I have read, you can not have a near field without having the far (radiating) field.
There is a basic rule about loading an antenna with this signal level meter. The indications from the meter are valid as long as changes or adjustments are made between the meter and anywhere in the transmitter. The meter indications may not be valid for any changes made beyond the meter (farther out the antenna or ground lead).
When you want an idea of how much power the transmitter can put out, it is easy to substitute dummy load resistors at different values in place of the antenna. The peak to peak voltage across the resistor read by an oscilloscope, can then be divided by two and multiplied by .707 to get the rms value. This value when squared and divided by the resistor value will give the power being fed to the resistor according to ohms law. I am usually curious about the values obtained using 50 to 220 ohm resistors.
It appears that the simple circuit shown above can work well into a wide variety of load values without using any additional load matching components. Using a 9v battery I measured the transmitter RF output power into several dummy load resistors as described in the previous paragraph. The result was in the range of about 5 to 7 milliwatts. They are listed below.
56 ohms 1.5v pp 5.02 milliwatts
150 ohms 3v pp 7.49 milliwatts
220 ohms 3.5v pp 6.96 milliwatts
510 ohms 5v pp 6.1 milliwatts
I was also able to run this transmitter on 3 volts but the power output was much lower – in the range of 300 to 400 microwatts. These microwatt levels could still be heard (not as strong) several miles away.
The circuit above is far from a representation of the amount of RF power output that can be supplied from a single transistor circuit. The main purpose of this project was to get an idea of what can be accomplished by simply coupling an antenna to a simple oscillator circuit.
It seems that the biggest disadvantage to all this simplicity is the difficulty in knowing exactly how much power is going up the antenna. Getting optimum power up the antenna is not nearly as difficult and is the main concept presented here. The dummy load resistors tell how much power can be put out with different loads but the exact load these random length antennas present to the transmitter is a bit more difficult to determine. These questions can be answered by delving into more sophisticated practices.
Cell phone outages in Boston highlight Ham Radio use
Southgate Amateur Radio Club
Runners weren’t the only thing stopped at the 2013 Boston Marathon following the bombing – cell phone operation screeched to a halt as well.
Another reason to keep your Amateur Radio License current. It seems that most commercial communications networks suffer most during emergencies…During the March 2011 tsunami warning for Hawaii Island, the cell phone providers were overwhelmed with calls from worried residents, despite pleas to stay off cell phoned except for dire emergencies. I was working at a commercial broadcast station at the time, and our staff had to rely on the wired phone backup to keep in contact with local civil defense officials. Texting seemed to work a bit better than cell phone voice during the emergency. While cell phones were unusable for…
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RT @USNGFlorida: Rapidly Deployable Amateur Radio (RaDAR) http://t.co/7ucUbY1zbu promotes #USNG to facilitate SAR. @ARRL_EMCOMM http://t.co/s26joUTRWo
Here’s an interesting program for those of us into portable operations. Aloha de KH6JRM.
See on radar-america.blogspot.fr
Following the Dorner saga in California and the Boston Bombings, there has been a lot of discussion surrounding online scanners. As someone who has feet on both sides of the fence on this issue, I think I’m well positioned to offer an opinion on it. My opinion centers around two words: responsibility and encryption. At the end of the day, the user of an RF scanner and the user of an online scanner must be responsible. The user of an RF scanner is self responsible but it’s hard to take into account the responsibility of what could be thousands of listeners of an online scanner. It then follows that some amount of responsibility falls on the owner/operator of the online scanner. The lack of responsibility, real or perceived will lead to the increased use of encryption by the public safety agencies that so many listeners wish monitor.
I believe that…
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Several CubeSats carrying amateur radio payloads are planned to launch on the Antares-110 mission in April.
On the CubeSat mailing list Jason Andrews President and CEO of both Spaceflight Inc and Andrews Space posted:
Spaceflight Inc recently completed CubeSat integration activities for the Antares demonstration mission including deployment dress rehersal. Spaceflight has two ISIPod deployers on this mission. One contains three 1U spacecraft for NASA Ames Research Center and the other contains a 3U spacecraft for a commercial customer. An image of the integration activity can be found here:
Among the amateur radio CubeSats on the launch are three Phonesats which will all carry Google Nexus smartphones similar to the pioneering UK smartphone satellite STRaND-1 that was launched in February. There will be two PhoneSat 1.0’s and one PhoneSat 2.0 on the launch.
PhoneSat 1.0 cost about $3500 and is built around the Nexus One smartphone, it operates on…
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Getting an Amateur Radio License is an essential preparedness skill. Watch and find out how easy it is! Here is a link to the PDF study guide that I used: ht…
Do you want to be an amateur radio operator (ham)? This youtube video provides some useful information. Good luck…see you on the bands. Aloha, Russ
See on www.youtube.com
In a typical engineering discipline, one spends four (or more commonly, five) years in classes learning more math, science, circuit analysis and classroom topics than you could ever fathom to understand.
Excellent article on how amateur radio can sometimes get you the job of your dreams. Thanks to his hard work and knowledge of amateur radio, Sterling Coffey (N0SSC), the ARRL Youth Editor, was able to secure an internship at the Very Large Array (VLA) in New Mexico. Coffey says the job really isn’t work–it’s fun. Imagine using all of that state of the art test equipment and those large deep space parabolic dishes. I’m jealous. Aloha de KH6JRM.
See on www.arrl.org