AmateurRadio.com

While this may not be a surprise to those with electrical engineering backgrounds, this is a first for me — never seen this sort of thing before. While the effect is very cool, it’s potentially very dangerous and you shouldn’t go jumping the fence at the neighborhood 50kW shortwave station to try it out.

Wikipedia on plasma speakers:

Plasma speakers are a form of loudspeaker which varies air pressure via a high-energy electrical plasma instead of a solid diaphragm. Connected to the output of an audio amplifier, plasma speakers vary the size of a plasma glow discharge, corona discharge or electric arc which then acts as a massless radiating element, creating the compression waves in air that listeners perceive as sound. The technique is an evolution of William Duddell‘s “singing arc” of 1900, and an innovation related to ion thruster spacecraft propulsion.

The effect takes advantage of two unique principles. Firstly, ionization of gases causes their electrical resistance to drop significantly, making them extremely efficient conductors, which allows them to vibrate sympathetically with magnetic fields. Secondly, the involved plasma, itself a field of ions, has a relatively negligible mass. Thus as current frequency varies, more-resistant air remains mechanically coupled with and is driven by vibration of the more conductive and essentially massless plasma, radiating a potentially ideal reproduction of the sound source.

After doing some looking around, I realize that I’ve seen a similar phenomenon in the past while visiting the Boston Museum of Science — the singing Tesla coil!  Here is a fun example:

(via Reddit)

Courtesy of N8NQH

Thanks to Tim, N8NQH for sharing a possible 60-cent fix for the loss of memory problems plaguing some Wouxun radios. He’s created a great little resource page for those looking to tackle this repair. According to him, the problem is a little 8-pin DIP surface mounted 24C64 serial memory IC.

Please note, however, that he makes it very clear that this repair is made at your own risk! Your mileage may vary, but at least it’s a possible starting place.

http://tim-yvonne.com/ham/wouxun-memory/index.htm

I had the opportunity this afternoon to be one of the very first people to go hands-on with the new dual-band Wouxun KG-UV8D HT courtesy of Danny at BuyTwoWayRadios.com. What’s the verdict? I’m impressed!

VHF/VHF dual receive — for the win! This is a great feature and, at least for me, one of the most compelling reasons to upgrade to this radio. It mixes the audio from the two frequencies so you won’t miss anything. Great feature for EmComm, especially. I personally don’t have a great need for cross-band repeat, but that’s just icing on the cake.

The text on the color screen is so much easier to read than on previous Wouxuns. There’s about twice the screen real estate and it makes the radio much more usable. Although I didn’t get a chance to play with every feature of the KG-UV8D, I can honestly say that this radio seems to be much easier to program from the keypad. I think that larger screen helps a lot. For the first time, I feel that I could field program one of these without the manual. Trust me, that’s saying something!

The radio seems slightly narrower and thinner than previous versions. This is a definite step up and it improves the ergonomics of the radio. The PTT button is large and segmented in a way that makes it hard to mistake it for a function button as with the KG-UV3D. The programmable buttons under the PTT are also cool. You can program it to activate the FM radio or to start scanning, for example. Very easy to customize.

The battery is different which is a little disappointing for those of us who have a collection of older Wouxun batteries, but I like the changes they’ve made to the way it slides on and off the chassis.

The rubber ducky antenna they include is OK, but for me a Smiley 270A would replace it in short order. And speaking of antennas, why can’t Wouxun figure out if they want to use SMA-male or SMA-female on these radios? I think we can all agree that they should just standardize on one or the other. This radio has a SMA-female connector while my KG-UV3D is SMA-male.

I’ve fallen in love with this little radio and I’ve only had it a few hours. When they begin shipping in a couple weeks, I will definitely be ordering one. While there aren’t really any must-have new features (except dual-receive), the radio just feels much more refined than other radios I’ve used that are anywhere near this price point.

Whether you’re a brand new ham looking for your first rig or you’ve been at this game for decades, you can’t go wrong with this $139 radio.

Update 4/28/2014:
If you click through to BuyTwoWayRadios.com, you will notice that the final price of this radio is now $159. If you order this radio, don’t forget to use the coupon code 139UV8D to get the original $139 price! Not sure how long this coupon code will remain active. Your mileage may vary.

Earlier this week the Wall Street Journal published an article about the growing prevalence of RFI from unlikely sources.  They quoted Tom Thompson, WØIVJ, of Boulder, Colorado:

Radio hobbyist Tom Thompson of Boulder, Colo., last year tracked a signal using a homemade contraption. After knocking on the suspect’s door, he traced it to ballasts on marijuana grow-room lights. He says he built a filter that the grower agreed to use.

Tom, a retired NOAA electronic engineer, created an entire web page devoted to the grow light ballast filters. According to his page, these ballasts are switching power supplies for high-pressure sodium or metal-halide lamps.

He goes on to describe the problem in good detail:

Typically the light fixture is removed from the ballast by about 25 to 30 feet.  Since this length is about a 1/4 wavelength on 40 meters, it makes a good “antenna” for 40 meters so the RFI may be strongest on 40.  I have heard radiations from these systems up to about 1/2 mile away.  Also, since the “antenna” is so low to the ground, the RFI is mostly vertically polarized which is important when tracking it down.

Check out his page to see how he built a filter that he says reduces the RFI by about 30dB. That’s some good ol’ ham ingenuity!

OK, now this is a pretty cool service.

My friend Clint Bradford, K6LCS, has opened a website where he is offering to program almost any HT you can think of for $35. The website is called HamRadioProgramming.com.

The process is very straightforward. You mail him your radio, he’ll program up to 60 memory channels of your choice, and he ships it right back via USPS Priority Mail. Don’t know the frequencies outside your immediate area? Clint will look them all up and program them in. Pretty darn slick.

Now, when I first heard about it I thought to myself, if you’re smart enough to pass an amateur radio exam, shouldn’t you be smart enough to program an HT?

Well, first it’s not really about being smart enough. My first HT was a little Kenwood TH-27A and honestly, it wasn’t that hard to program. Things were different in the old days! 🙂 Fast forward twenty (plus) years, my Wouxun and Baofeng radios are a different story. If hadn’t purchased the programming cable, learned the software, figured out how to get the drivers to work with the radio, etc., I’m not sure my radios would have ever been programmed. In fact, I’ve never been able to program my Baofeng UV-3R because I couldn’t get the drivers to work. Could be just me, but it can be a real pain.

But, let’s say you’re not intimidated by learning new software and tweaking around with USB drivers. This service still makes a lot of sense for those who don’t do a lot of programming because you save the cost of buying those foolish programming cables. I have a different one for both my Wouxun and Baofeng radios and I think I paid $15 for each one.

If you want to save yourself a bunch of time, technical headaches, and the cost of a programming cable, take a look at what he’s offering. If you’re not interested, I bet you know someone who might be.

BuyTwoWayRadios.com released a flyer on Friday detailing some of the specifications for the Wouxun KG-UV8D.

At first glance, the specifications of the KG-UV8D above appear virtually identical to the Wouxun KG-UV6X (if someone can spot a difference, please let me know).

BuyTwoWayRadios.com has confirmed that they plan to offer the radio at $139.99 and will begin taking pre-orders this week. The KG-UV6X is $169.99 at Powerwerx (but also includes a dual-slot rapid charger at no extra charge).

Source: BuyTwoWayRadios.com blog via Brick O’Lore

Over at Make, they’ve posted an interesting project showing you how to convert your $35 Raspberry Pi into a wide coverage FM transmitter.

This simple hack turns your Raspberry Pi into a powerful FM transmitter! It has enough range to cover your home, DIY drive-in movie, a high school ball game, or even a bike parade (depending on the stragglers).

The hack, called PiFM, uses hardware meant to generate spread spectrum clock signals and outputs them as RF energy on the Raspberry Pi’s GPIO (general purpose input/output) pins. The original creators report getting a range of 50m through heavy walls and multiple rooms.

Luckily, they include this helpful warning:

The Raspberry Pi’s broadcast frequency can range between 1Mhz and 250Mhz, which may interfere with government bands. We advise that you limit your transmissions to the standard FM band of 87.5MHz–108.0MHz (see Step 3) and always choose a frequency that’s not already in use, to avoid interference with licensed broadcasters.

Good advice, don’t you think? :-/