KD6W

At a flea market of course! Some dude had a couple of tables with rows of little bins with mostly connectors and adapters and after about 10 minutes of staring at all the little goodies, there they were! I think the 2 cost me a whopping $10.

The adapter losses you speak of are negligible assuming the adapter isn't a dead short or an open. Don't laugh, I had one open up like making a huge attenuator and I couldn't figure out why. I was losing so many dB but I would still see a tiny signal, just enough to tease me. Then I ohmed it out and I quickly find myself saying things like "drat" and "curses"... The next sound you heard was the adapter hitting the rim into the shit can. Yes RP SMA blows, but exists because some genius thought they could stop us from doing exactly what we are doing. Those fools. What you seek is this little gem, so now at least you know they exist. You just gotta know where to look. - KD6W

I know what you mean. I like doing my own too. I have a Bausch & Lomb stereo scope with different objective strengths and variable zoom for doing all the fine hand placement cuz I can't see the tiny stuff ever since I got my eyes blasted. I'm building a hot melt flow oven from a black and decker toaster oven for soldering BGA parts.

Swaggie and others, We (hackers and hams alike) are notorious for being cheap. For most getting started in radio starts with the fine art of listening and is usually preceded by the desire to transmit, and usually after receiving a license to do so. Then there are a very few who like to live dangerously and start transmitting without a license giving us (and the FCC) sport; we get to hunt you down. Starting with an SDR is the big no brainer for listening. Transmitting can also be done very inexpensively too if you are handy with a soldering iron and can read schematics. But I understand the need to get on the air quickly too. Flea markets are a great place to look for bargains on radios but bring a friend who knows something about them and a Volt/Ohm meter. Also, new Chinese radios have flooded the markets and are well within in your budget. For example, I was in Dayton and picked up a V/UHF radio for $45 complete with battery, wall charger, antenna and wrist strap. Adding and external antenna is trivial and can be crafted out of plumbing parts. The rest is up to you. The test for getting your license is VERY easy, no longer requires Morse code and yes, you have to register with a government agency. But dems da rulz. I came over to this forum because of all the OTHER helpful people who are just as friendly and can help me on my other projects. As the NSA sez, sharing is caring . See you on the air? - KD6W

Use stranded copper wire for the elements. Any durable plastic thick enough to take strain will make a good insulator. I have used chunks of white PVC pipe and acrylic squares to strips of phenolic board material. When ever I see a porcelain insulator at the flea market, I pick them up and then promptly loose them on my bench. The coax you choose will likely be for economic reasons. Using RG6 coax will serve the purpose for reception applications. You aren't transmitting so any coax will work but I should caution you the light duty stuff will not work as well at the higher frequencies. All coax has a frequency chart like page 6.6 in this link... http://www.belden.com/resourcecenter/tools/cablefinder/upload/06-3_15.pdf The chances of getting struck is dependent on where the tower is located geographically and how far above the antenna is to everything else around it. My antennas don't exceed the height of the natural tree canopy around me but I don't have a monster like that one either (though I wish I did!). The DC resistance of the antenna is near or at ground potential to the tower it's mounted to. So, if the antenna takes a hit, the path of least resistance will shunt the blast, usually down the tower. If some of the charge goes down the coax and no way to dissipate the charge into a protection ground, any equipment connected to it will carry the path to ground and likely let a bunch of magic smoke out in the process. - KD6W

That's easy, a 1/2 wave dipole. You will need 10 feet of wire, three insulators, a bunch of 75 ohm coax with the appropriate connector for your dongle on one end (TV coax will work fine but avoid using the really stiff stuff) some wire cutters and a soldering iron and solder. The formula for making a dipole is simple; the 1/2 wavelength in feet is equal to 468 divided by the frequency of interest in MHz. so 6 meters is 50 MHz and 468 divided by 50 equals 9.36 which is 9' 4 3/8". Dipoles are typically center fed through a balun (or transformer) for transmission but we don't care about matching that impedance so a simple insulator in the middle to split the length into 2 equal length pieces, each being a quarter wavelength or 4' 8 3/16" but leave about three inches of extra length. Connect the center of the coax to one leg and the coax braid to the other and secure those joints mechanically with one of the insulators to hold them apart and from being ripped apart and viola! Attach a remaining insulator to each end to make the measurement at each end become the desired length and then string that puppy up as high as the coax will let you while still connected to the dongle and orient the elements broadside to the listening direction of interest. Coincidentally, to make a 1/4 wave vertical antenna the same formula is true but braid needs radials to make the ground plane. With the center element connected to the center conductor of the coax pointing straight up 4' 8 3/16" with 4 or more radials of the same length plus 10% pointing in a North South East West configuration with the horizon, then the antenna is Omnidirectional. The collinear antenna Darren made will provide more gain but will get huge at 6 meter frequencies. It's design uses the same formula and you get the idea. A two section collinear is 9 feet tall and so on. And then there are monsters like this one... http://www.m2inc.com/index.php?ax=amateur&pg=116 Not cheap but GAD ZOOKS it's huge! 70' boom and 83 lbs. - KD6W

Sad to say, VOA in Westchester (Bethany Relay Station) has been silent since 94 and the antennas are gone. {sniffle} Also - I regularly go out with a bag of dope and get my antennas as stoned as possible to help improve the signal quality. - KD6W

Do you have a receiver and or a license to transmit? Anybody can listen... it's free.

It's not uncommon for small transmitters (and SDR's) to drift around. You can be sure the commercial power stations are locked to one or more frequency standards like a GPS disciplined ovenized crystal. The little guys aren't tuned as often or as critical and 7 kHz is slightly out of spec but not a huge deal in the grand scheme of things. Accuracy depends on how you measure the center frequency. If they ever put up a 1 kHz tone, measure the deviation of the carrier 3dB down on each side of the carrier lobe and divide in half. If the center is off their assigned frequency, you might have a future career at the FCC, they could use a few people like you!

Or perhaps you are so narrow you can see the 7th VSB of channel 15 WMPI in Pensacola Florida (NBC) just south of you about 45 miles away. They are licensed to radiate with 1000 kW ERP (1 megawatt) from the gulf coast from a 560 meter tower. If you point your antenna due south they should easily propagate into your neck of the woods. Try opening the span in the SDR up to see if you can get a picture of the "Bart's head". - KD6W

Very cool and thanks for the update. I'm very interested to see what you come up with once boards come up to production. I'm very dubious about sponsoring any more kickstarters as I have already funded a few duds. Sorry, not you but I'm twice bitten. 73 -KD6W

In my travels, I have not experienced a dumb question, but I have provided numerous dumb answers and stupid looks for increased dramatic effect. Yes as Cooper points out, if the transmitted signal doesn't exceed the specifications of the receiver. But there is more to this. For the purpose of transmitting, what information you plan to transmit (is this a broadcast for many people to hear or all directed to one receiver?) and how far will greatly effect what kind of amplifier you end up with. More to the point, which frequency you select and how far you are trying to go will dictate the type of antenna and how much power you will need. Which antenna you end up with will indicate what kind of power level you need to produce to over come path losses in the receiver(s). Which amp you buy will have some set of characteristics (some worse than others) that you will wish to filter out to remove undesirable by-products (stuff you don't want like harmonics and so on). Once you factor all those things together, you will improve your odds of being received successfully at the receiver, assuming the receiver isn't deaf, pointed in the wrong direction or turned off. For actual useful purposes, a typical 2 meter (144 MHz) radio with a 5 watt rating, using narrow band FM modulation can go miles on a stupid little antenna (as seen on TV) to a receiver with a higher location and a better antenna or preamp or both. That same radio talking to a similar radio at the same altitude can MAYBE go a mile. Experiment first with 1/2 watt amps into a dummy load on the FRS band 49 MHz (or the 915 MHz) to characterize the amplifier first. If the output isn't very linear then try using the most narrow frequency usage as possible - be the ham - and see what you can do with the SDR receiver sticks and different antennas. If the amp has a flat and clean output, try different types of modulation (AM/FM/SSB/CW a.k.a Morse code or High Speed CW commonly referred to as OOK or On Off Keying). AM eats power to produce the carrier, FM will drive the amp class C = lots of heat. Single Side Band and CW are the most efficient but can make an amp go "non-linear" but only use power when information is sent. There are tons of books and articles to read on all this stuff but by far the most efficient method for moving data are the digital modes for brute force information transfer like OFDM (Orthogonal Frequency Division Multiplexing) which is a HUGE topic. SDR is a white hot topic in numerous communities for one simple reason, the darn things are REALLY inexpensive and can do many things. I have talked to people on radio all around the world and through satellites. I tend to operate in big contests just for the fun of it but my passion is making things and then going out to try it and see if it blows up or works. I have been farting around with DSP for years and SO glad that others are jumping in on the SDR train. I'm just getting my arms around this stuff too. Maybe I'll find you on air some day, legally please. As we say 73 - KD6W

Hmmm, Kickstarter (website) sez "funding cancelled - by the creator"...well, that's a bummer. Change name - reboot?

My name is Joel aka KD6W (just ask the FCC, it's their fault!) I live and work in Silicon Valley (San Francisco / San Jose) Favorite game: BF4 / ROBOTRON 2084 Favorite OS: IBM 370 JCL? One that works? Favorite console: My first, Atari 2600, my current PS4 Nationality: US Accent: midwestern Gender: Male Age: We're up there but NOT over the hill! Race: White Height: 6' Status: Wife=1, Children=1 (aka happy!) Build: Not flabby but not ripped either Favorite band: Grand Funk Railroad (MORE COWBELL!) but lately getting into a local artist - Blu Mar Ten Favorite book: The Martian Chronicles Favorite author: Isaac Isamov Favorite movie: The Big Lebowski Favorite director: Stanley Kubrick Favorite TV Show: Star Trek (the original) Favorite actor: toss up - Al Pacino /James Earl Jones Favorite actress: toss up - Jenna Elfman / Hedy Lamarr Favorite Pinup: Raquel Welch of course... (http://en.wikipedia.org/wiki/File:Raquel_Welch_in_deer-skin_bikini.jpg) Favorite Comedian: Robin Williams (I can't believe he is gone, I'm praying he is in a better place. Very tragic and sad) Hobbies: Camping, Amateur Radio (RF hacking), Scuba Dive, Photography, Motorcycling, Pwning Noobs Vehicles: 11 Silverado/ 99 Porsche Boxster/ 98 VFR 800fi Occupation: Sr. System Designer - Satellite and Terrestrial DTV Broadcasting