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hardware : by Tommy - November 18th 2009, 09:54PM
Well, today I received my first box from The Great Internet Migratory Box Of Electronics Junk. As predicted, there was a lot of random stuff inside. Several bags of discrete components (capacitors, LEDs, etc), some DC motors of varying sizes and ratings, some copper-clad PCBs for homemade etching (with transfer film - very tempting), a couple of pagers, some random gears and knobs, a nice pack of 7 segment LEDs, some project enclosures, some random PCBs, wire wrap supplies, a DIY 9-pin serial cable and connector, and a nice looking character LCD that was unfortunately cracked right in the center.

Quite a bit of stuff to choose from. I chose to take out a 9V battery clip, some 7-segment LEDs, and the 2 project enclosures. I plan to use the parts for a solar-powered arduino project I read about and have been wanting to try out.

I'll probably pick some unsuspecting geek and mail the box out to him in a couple days. That is, after I dig up some worthy additions to the box. Interested in joining the ranks? Sign up!

tags: electronics, kits, junk

( Comments : 0 | Full article )

hardware : by Tommy - November 10th 2009, 11:11PM
What a fun idea! The Great Internet Migratory Box Of Electronic Junk, TGIMBOEJ for "short", looks a like a neat prizefest for geeks all over. I know I'm all for it, I may even start a box of my own simply because I have so many extra electronic parts laying around! As the name implies it doesn't have to be just computer parts or just consumer electronics, it can be any electronic parts you happen to have. I have some leftover discrete components as well as PC parts I'm going to include should I receive a box soon. I've signed up on the wiki to put me in the pool of recipients. I'll, of course, let you know when/if I receive a box and what all I find useful in it. Sign up and send your old electronic parts to some random geek!

tags: electronics, kits, junk

( Comments : 1 | Full article )

Elecraft KXAT1 Antenna Tuner
radio : by Tommy - April 19th 2009, 06:50PM
I recently added the KXAT1 antenna tuner kit to my Elecraft KX1. The antenna tuner allows me to automatically tune up any non-resonant antenna quickly. Construction took one evening. As usual, winding the toroids was perhaps the most tedious part, but "zen-like" while I was doing them (as I heard it put by someone). I did have trouble with the transformer. It can be tricky and I'll warn other kit builders to check out this thread if they have trouble. I also found some pictures from a japanese ham helpful, but I've since lost them. :(

After building and installing the tuner, I purchased 40ft of some "silky" 26AWG wire from TheWireMan as suggested by Elecraft. I cut the wire to give me two lengths. One length is 24ft and the other 16ft. The 24ft length is my radiating element and the 16ft acts as my ground. The tuner quickly finds a nice 1.1-1.0 match and gives me full KX1 power out (~4W). It makes for a very lightweight, field-portable antenna. I can also use my crappie poles to elevate one end if trees are unavailable.

I use a BNC-to-binding post that I purchased at EPO in Houston. While at EPO, I also picked up a small 12V 1.3Ah gel cell battery. The UB-1213 is about 3.8" x 1.7" x 2" and provides adequate power for portable QRP work. If I was going to operate for very long, I may go with a little larger capacity gel cell, but for now this makes a very lightweight and super portable setup that allows me to get one the air quickly.

tags: ham_radio qrp kx1 kit

( Comments : 0 | Full article )

Elecraft KX1
radio : by Tommy - April 5th 2009, 06:27PM
About two weeks ago I completed construction of my Elecraft KX1 ham radio kit (serial #2182). It wasn't the easiest build I've done, but definitely the most fun. The purchase was funded almost totally by referral bonuses from Dreamhost. When anyone signs up for an account with my referral link I get a kick-back. I had let the bonuses build up over time and eventually had enough to cover the radio, but I digress.

The KX1 is a "trail-friendly", portable CW ham transceiver. There's plenty of other sites that will give you more detailed information about this gem of a radio. I finally got to use mine yesterday for more than a couple of minutes and I must say I totally love it. The receiver is great, the noise floor is low, the filters are tight, and the features are really packed into this tiny radio.

My antenna was a random wire made from speaker wire with one end elevated to 20' using a BnM Black Widow 20' Crappie Pole purchased at Bass Pro Shop in Shreveport, LA. The antenna sloped down to my BLTPlus antenna tuner which tuned the random wire without any problem. I had the tuner hooked into the KX1 with a short piece of BNC cable.

In short order I was copying stations on 7.030Mhz (40m QRP) and trying to copy the faster stations lower down on the band. I had to tighten up the filters because of the sheer number of signals I was able to pull in. I wasn't able to raise any station due to my diminished transmit power. (I was running off of internal AA batteries because my gel cell hadn't been charged in quite some time.) I was also impatient due to the strong wind, fading daylight and biting insects.

Continue reading...

tags: qrp ham_radio kx1 kit

( Comments : 0 | Full article )

Rockmite 20m
radio : by Tommy - December 22nd 2008, 12:57AM
After almost a year of procrastination I got around to finishing a Rockmite 20 radio kit. The Rockmite is a single-frequency crystal-controlled ("rock-bound") low-power CW HF radio. Say that 10 times fast!

I bought the kit sometime last year and just never finished building it. I had all of the components soldered in, but I never mounted the board in any enclosure. W5USJ, Chuck, Don, K5DW, gave me a metal enclosure during a North East Texas QRP Club meeting. It wasn't until last Friday that did anything with it. I knew the Rockmite needed a home, and here was a nice case for it. I drilled some holes in the cabinet, more or less eyeballing it. They're not perfectly aligned, but pretty close. So now the little radio is mounted, all of the connectors are soldered in and the radio is functional.

It only puts out about W at 14.060MHz, on the 20m amateur radio band, but because I mostly operate during the afternoons, 20m is my favorite band for now. I may need to boost myself up to a "full gallon" QRP and get a 5W amplifier like the one Chuck designed, which I might get from QRPme.

Also on my "to do" list, is to add a PicoKeyer chip to the radio which greatly adds to the experience of using it.

update: I got the PicoKeyer chip installed this afternoon. I love the features it provides. The Memory Keyer is vital for QRP work and the hands-free "Tune" feature is great for field-portable antennas. Most of the other features I don't use, but I still think the chip should be incorporated into the original design.

tags: qrp ham_radio kit

( Comments : 0 | Full article )

One Tube Regen Receiver
radio : by Tommy - January 24th 2007, 9:43PM
Well, it's taken me a while to make a post about this one. It was a goal of mine after I completed the simple foxhole radio and one I set out to complete over the Christmas break. I decided since the crystal set was the simplest radio to build, what's the next step? The one-tube regenerative circuit was the answer.

Lately I've been reading quite a bit about radio history and have read about the huge leaps in receiver technology with the advent of the "audion" or vacuum tube. A lot of initial growth in radio reception is thanks to this circuit designed by Edwin Armstrong while still a junior in college in the early 1900s.

I scoured the net looking for parts (chiefly the 3S4 tubes) and kept coming back to Borden Radio Company. Rather than drop alot of money on shipping from various sources, I purchased a kit from Borden. It also happens that he doesn't live too terribly far from my parent's so I was able to meet up with the owner/operator, Lance Borden, over the Christmas holiday.

I pieced the kit together in two evenings. The first evening was spent winding the coils and mounting the hardware. The next night was spent meticulously wiring the components as outlined in the directions. (Maybe color coding the wires would have made the instructions a little clearer, but I can't complain.) The radio worked right from the get-go. It's tuned for broadcast AM reception and works like a charm. As you can see in the picture it requires quite a few batteries to power the tube, but it is 100 times louder than the crystal set and much more sensitive. I've heard stations all over the nation on this little set. This evening alone I was able to quickly tune into WWL 870 from New Orleans as well as KOA 850 out of Denver, Colorado.

The controls are finicky and not really what the casual listener would want, but the sensitivity and simplicity makes it worth the effort.

Continue reading...

tags: radio kit

( Comments : 3 | Full article )

Worlds Simplest Radio Redux
radio : by Tommy - December 5th 2006, 08:41PM
After the success of my last post about my simple razor-blade radio (link here), I began work on making a slinky dipole. I tried to use 2 Slinky Jr. toys which I bought at Walmart for $.88 each. It didn't work as well as I had hoped. After quite a while of the coils sitting on my desk and playing with them, it dawned on me that I could easily use the small Slinkys as the tuning coil for a simple radio. I started to do the math to find the inductance of the coils. I measured 1.5" in diameter, which gave me 4.7" in circumference. I started to count the coils to calculate the open-air coil formula that I had used before. I stopped and thought, why bother? Just try it out!

I stretched the slinky to the length of the board I used on the old razor-blade radio and tacked it down. I made the proper connections, using a diode first. (Ground went to the 3rd prong on a power outlet, the antenna wire and clip was hooked to my 20m ham radio antenna, on my roof) I started with the diode because it is far more efficient than the razor blade, which equates to louder audio in the earpiece.

Right off the bat I was able to hear shortwave broadcast stations! Wilder still was my ability to receive the signal without having the antenna clip attached! I tried various points along the coil, finding I was able to hear certain stations better at different points on the coil. As before, I was able to hear local AM broadcast stations just fine, and various strong shortwave stations with a "shorter tap".
After listening with the diode for a few minutes, once again amazed at the simplicity of the setup, I switched to the razor blade setup I had used in the past and was just able to pull out the same local broadcast signal from before.

Continue reading...

tags: radio kit

( Comments : 5 | Full article )

Worlds Simplest Radio
radio : by Tommy - August 3rd 2006, 12:58AM
I just finished making quite possibly the world's most simple radio. I had read a few HOWTOs for constructing a crystal radio. Some links offered the basic formulas for figuring the specs needed for the coil if you wanted to tune various frequencies. I purchased 3 spools of "Enamel-Coated Magnet Wire" from Radio Shack for ~$5, and picked up a crystal ear piece while at EPO in Houston.

After reading that just about any round object will do for a coil-form, and not having an empty toilet paper tube, I settled on an empty fish food container. It was small, compact, and just the right size - plus with the screw on lid, I can keep the antenna, ground and ear piece inside. I rinsed out the fish food residue, tapped 4 small holes with a drill bit and started wrapping the 22awg copper wire around the bottle. Every 5 turns I would wrap around a toothpick. After wrapping the bottle - which took a while - I ended up using about 30ft. of wire. (FWIW: my coil came out to be about 118uH) The toothpick wraps were then scraped free of the enamel coating to make antenna taps for rough tuning. (how this works) After ensuring there were no shorts along the coil body, I hooked up the 1N34 diode, ear-piece, ground wire and antenna and was greeted with some shortwave radio broadcasts. The first station I heard ID was WWCR out of Nashville, Tennesee, although there are plenty of others I can hear.

The trouble with such a simple receiver (no variable capacitor) is that there is little selectivity and the listener is bombarded by 2 or more stations at once - a mixing of all of the signals within a range of frequencies.

Continue reading...

tags: radio kit

( Comments : 102 | Full article )


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