From the ARRL Letter – 5/31/12

Two items in today’s ARRL Letter caught my eye:

FCC News: FCC Expands Part 95 MedRadio Rules to Allow Devices in 2360-2400 MHz Band. In a First Report and Order and a Further Notice of Proposed Rulemaking (ET 08-59) released on May 24, the FCC decided to expand the Part 95 Personal Radio Service rules to allow medical devices to operate on a secondary basis in the 2360-2400 MHz band. These devices — called Medical Body Area Networks (MBAN) — provide a way for health care facilities to monitor their patients via wireless networks. Because use of these frequencies will be on a secondary basis, MBAN stations will not be allowed to cause interference to — and must accept interference from — primary services, including radio amateurs who operate on a primary basis in the 2390-2395 MHz and 2395-2400 MHz bands. Read more.

MARS: House Armed Services Committee “Urges” MARS Coordination. On May 18, the US House of Representatives approved HR 4310, The National Defense Authorization Act for Fiscal Year 2013. This bill authorizes appropriations for military activities and prescribes military personnel strengths for Fiscal Year 2013. When the House Armed Services Committee sent the bill to the House, it included language in support of the Military Auxiliary Radio System (MARS) and called for the three MARS branches — Army, Air Force and Navy/Marine Corps — to be brought under one umbrella. Read more.

I don’t have much to say about the MARS item, except to say that I’m surprised that Congress would have much to say about it. I’m a little more concerned about the Part 95 decision, but what can I say? Amateurs are not really using that spectrum, for the most part, and until we do, encroachment is inevitable.

Ham Radio in the News – 5/30/12

China/PhillipinesHam radio pulled into territorial dispute. China is using amateur radio to claim sovereignty of Scarborough Reef. The Chinese say that in 1990 a German ham was told  by the Philippine ambassador that the reef was not within Philippine territory.

Amateur radio essential tool. Behind the scenes at every Drivesouth Rally of Otago a team of local amateur radio enthusiasts works tirelessly to keep track of every car. Their support is vital to the three-day event, which started last night, as there is either unreliable or no cellphone reception where many of rally’s stages are held.

W6G Salutes Golden Gate Anniversary. The San Francisco Amateur Radio Club helped mark the 75th anniversary of the opening of the Golden Gate Bridge by contacting other amateur radio operators this Memorial Day weekend.

Horse fence antenna: progress report and request

In my recent post, More from Dayton 2012, I reported on the horse fence antennas made by KF4BWG, mentioning that every time I see them, I get the idea to try and make my own. Well, yesterday, I went down to Tractor Supply and bought 500-ft. of 2-in. PolyTape fencing material and some clamps. I even got lucky and got the tape on sale. Instead of $64.99, it was on sale for $54.99.

The clamp makes good contact with the conductors in the poly tape, but now, how do I connect it to the center insulator?

This evening, I started playing around with it. The first thing I did was to clamp the tape with the clamps I bought. What I discovered is that the clamps really don’t make contact with all the conductors. They tend to bow, and some of the conductors in the center of the tape were open.

To get around that, I used an X-Acto knife to separate the conductors from the tape and bend them back so that they lay on top of the tape. Now, when I tighten down the clamp, I get a good connection on all conductors.

The problem I’m having now is how to connect the Hy-Q dipole center insulator that I have to the tape. What I need is some kind of clamp that will connect the solid copper wire coming out of the center insulator to the tape clamp. Anyone have any ideas? I can see drilling a hole in the tape clamp to secure the copper wire.  Not only would that connect the tape to the center insulator, it would take out the bow in that clamp and make an even better connection to the conductors in the polytape.

Extra Class Question of the Day: Bipolar junction transistor characteristics

Perhaps the most popular type of transistor is the bipolar junction transistor (BJT). Bipolar junction transistors are three-terminal devices, called the emitter, base, and collector.  In an NPN transistor, the emitter and collector are N-type material and the base is P-type material. In a PNP transistor, the emitter and collector are P-type, while the base is N-type. The base is sandwiched between the base and emitter, so there is a diode junction between the base and the collector and the base and emitter.

Figure E6-1

Refer to Figure E6-1 above. In Figure E6-1, the schematic symbol for a PNP transistor is #1. (E6A07) #2 is the schematic symbol for an NPN transistor. The arrow in both symbols shows the direction of the current flow.

When the base-emitter diode is forward-biased, a current, called the base current will flow. If there is an appropriate voltage between the collector and emitter, this small base current will cause a much larger current to flow between the collector, through the base to the emitter. The amount of base current controls how much collector current flows. This is how transistors amplify signals.

The change in collector current with respect to base current is the beta of a bipolar junction transistor. (E6A06) This is also sometimes called the hfe or current gain of a transistor. The change of collector current with respect to emitter current is the alpha of a bipolar junction transistor. (E6A05)

Another important characteristic of a bipolar transistor is the alpha cutoff frequency. This is a measure of how high in frequency a transistor will operate. Alpha cutoff frequency is the frequency at which the grounded-base current gain of a transistor has decreased to 0.7 of the gain obtainable at 1 kHz. (E6A08)

Resources

What resources have you used for learning how transistors work?

Toying with tubes

As I mention in my Dayton report, I attended an interesting talk on homebrewing with tube circuits. This evening the speaker, Grayson, TA2ZGE, posted the following to the QRP-L mailing list:

I have had a lot of people ask me, after my talk on Hollow-State Homebrewing at FDIM about where they could find interesting theratron (vacuum tube) circuits to build.   So I thought I would pass along some references and links to get people started:

Dave’s Homemade Radio. This guy is a real craftsman and homebrew whiz with tubes.  A must visit!

Max Robinson’s Fun with Tubes. Max has a GREAT tube cross reference guide that lists types by type and application.

Jeff Duntemann’s Junkbox. Lots of interesting tube homebrewing ideas and circuits + LOTS of info on tube categories.

Electric Radio Magazine. If you are interested in tube gear, homebrewing with tubes, restoring tube equipment, you will definitely want to subscribe to this magazine and get the back issues.  It’s been around since the late 1980’s and is edited by Ray Osterwald, N0DMS, who write a lot of the more technical tube articles.   They have an index to search for back issue articles.  Look for projects by Bob Dennison (SK) and Bruce Vaughn.  These guys had many, many great thermatron projects!

If you have any questions on thermatron homebrewing, just let me know.

73,

Grayson, TA2ZGE

Fun stuff!

From my Twitter stream – 5/27/12

10 Ways to Destroy an Arduino : Application Note ANCP01 http://t.co/Of1XM8g4 Good to know. o_O

 

G7IGB
Great vintage RSGB video – How to become a radio amateur http://t.co/NKydLm4I via@youtube #hamr #hamradio #rsgb

??????????? ??????????? ???: ??????????? ??????????? ??? ??????!! ?????… http://t.co/wdpY1omR#YoutubeHam3 #Hamrjp
Nuts. I lost the Japaneses characters in the last item above. Apparently, it is  two friends talking about amateur radio in Japan. I don’t understand Japanese at all, but you can tell that they are having a lot of fun doing this video.

Hot off the (digital) press: 21 Things to Do After You Get Your Amateur Radio License

21 Things21 Things to Do After You Get Your Amateur Radio License is now available for the Kindle (Amazon) and Nook (Barnes&Noble). Written for the new ham—or the ham that hasn’t really been all that active lately—its 21 chapters include:

  • Join a club
  • Join the ARRL
  • Find an Elmer
  • Buy a radio
  • Get on the air
  • Set up a shack
  • Buy some tools
  • Buy a digital multimeter (DMM)
  • Build an antenna
  • Build a kit
  • Go to a hamfest
  • Learn the lingo
  • Subscribe to mailing lists, blogs, and podcasts
  • Upgrade to General
  • Go to Field Day
  • Learn Morse Code
  • Get to know your (ham) neighbors
  • Buy QSL cards
  • Join SkyWarn, ARES, or RACES
  • Participate in a contest
  • HAVE FUN!

 

More from Dayton 2012

After going through the materials I brought back from Dayton, I found a few things that I failed to mention in my previous post.

  • Horse fence antennas by KF4BWG. I’ve seen this guy at the last couple of Daytons that I’ve attended, and every time I see his antennas, I think what a great idea this is. Then, I make a mental note to go to Tractor Supply or some such place and get some of this material and make my own. Then, I promptly forget to do it.
    This does seem like a great idea, though. Not only would the antenna be very strong and light, but it should also be very broadband.  KF4BWG claims an SWR less than 1.4:1 across the entire 80m band, less than 1.3:1 across the entire 40m band, and 1.1:1 across the 20m, 15m, and 10m bands.
    When I mentioned to KF4BWG my plans to duplicate his antenna on my own (his cost $85), he told me that the quality of the fencing material that Tractor Supply sells is not as high as the stuff he uses. That may be true, but I’d bet it will  work just fine. Now, I just gotta do it.
KF4BWG Antenna

This antenna made from horse fence material is very broadband.

  • TubeProjects.Com. I think that I may have written about this company/website  before. The website lists three “products:” an audio amp, a benchtop power supply, and a VTVM. I called them products, but all the website is selling is construction manuals…at $35 a pop.  They do mention that they plan to sell chassis for these projects in the future. Once nice feature is that they have a resources page that lists  parts sources, books, and other websites with tube project information.
  • Society of Amateur Radio Astronomers (SARA). As if I didn’t have enough going on, I’m tempted to join SARA. According to the website, the Society of Amateur Radio Astronomers (SARA) is an international society of dedicated enthusiasts who teach, learn, trade technical information, and do their own observations of the radio sky. SARA was organized in 1981, and today has hundreds of members worldwide. The group consists of optical astronomers, ham radio operators, engineers, teachers and non-technical persons.
    At their booth, the SARA people were touting the Radio Jove Project, a “hands-on educational activity that brings the radio sounds of the Sun, Jupiter, and the Milky Way to terrestrial students, teachers, and the general public.” They sell a $190 starter kit that includes a 20m direct-conversion receiver, parts to construct two dipoles, and a CD ROM with SkyPipe software and general information. Since many hams will already have a 20m receiver, and know how to build a 20m dipole, it seems to me that all you’d need is the software.

Extra Class Question of the Day: Earth-Moon-Earth communications

One of the more exotic things that amateur radios do is earth-moon-earth (EME) communication, sometimes called “moon bounce.” As this name implies, radio amateurs actually bounce their signals off the moon. This is the ultimate DX. The approximate maximum separation measured along the surface of the Earth between two stations communicating by Moon bounce is 12,000 miles, as long as both can “see” the Moon. (E3A01)

Because the signal travels such a long way, you need to do everything you can to avoid signal loss. So, for example, scheduling EME contacts when the Moon is at perigee will generally result in the least path loss. (E3A03) Perigee is the point at which the Moon is the closest to Earth.

Because the signals are so weak, it’s also important to use equipment with very low noise, so that the signals don’t fall below the noise level. That being the case, the type of receiving system that is desirable for EME communications is equipment with very low noise figures. (E3A04)

EME communications can take place on both the 2m band and the 440 MHz band. The frequency range that you would normally tune to find EME signals in the 2 meter band is 144.000 – 144.100 MHz. (E3A06) The frequency range that you would normally tune to find EME signals in the 70 cm band is 432.000 – 432.100 MHz. (E3A07)

As you can imagine, there are not many operators working moon bounce. You don’t just get on an call CQ—generally you set up a schedule with another operator to contact one another via moon bounce. At the appointed time, the operators take turns transmitting, while the other listens. Time synchronous transmissions with each station alternating describes a method of establishing EME contacts. (E3A05)

One interesting phenomenon is libration fading. Libration fading of an Earth-Moon-Earth signal is a fluttery, irregular fading. (E3A02) This fading is caused by the irregular surface of the Moon, and the peaks can last for up to two seconds on the 2m band. These peaks can actually help operators make contacts when they would otherwise be impossible.

Dayton 2012: Another great ham radio experience

Dayton 2012 TicketMy Dayton experience started at 3:45 am Thursday morning. That’s when I had to get up so that I could make it to the Fairborn Holiday Inn in time for the first session of this year’s Four Days in May (FDIM). FDIM is a one-day conference put on by the QRP Amateur Radio Club International and is a great way to start the “Dayton experience.”

There were somewhere between 300 and 400 attendees at this year’s event, and we were treated to six very fine presentations. They included talks on using microcontrollers for various projects, software-defined radio, VHF and UHF for QRPers, homebrewing with “hollow state” devices (more commonly known as tubes), using open-source electronic design tools, and operating pedestrian mobile. The two talks that I enjoyed the most were “Hollow State (Thermatron) Homebrewing” by Grayson, TA2ZGE/KJ7UM and “Leveraging Free and Open Source Tools in Homebrewing” by Jason, NT7S.

Two things about TA2ZGE’s talk stood out for me.  First, was his method for homebrewing tube circuits. What he does is to take a Dremel tool and create pads on a bare piece of circuit board material, including pads that you can solder a tube socket to. Using this breadboard, you can create prototypes “Manhattan” style. Second, was the list of online resources. I’ll post those in another blog post. Grayson’s talk has certainly given me the incentive to use those “tubs of tubes” as I’ve been threatening to do now for several years.

Jason’s talk was about how he used open-source design tools to create his latest kit, the OpenBeacon, a crystal-controlled QRPp beacon transmitter. There are more out there than I realized. I’m thinking of asking Jason if he would be interested in expanding his paper into a small book that I could publish for him.

Thursday evening, they had their normal show and tell and vendor night. At this event, those selling kits and keys set up shop in the ballroom. Jason was selling his kits and the Four States QRP club had some of their kits there, too. I don’t know how much, if anything, they charge the vendors, but perhaps next year, I’ll take some of my books. They’re not exactly the right audience for them, but perhaps they’ll buy them for friends and family.

Friday morning, I got up early again, so that I could make the 7:30am bus to the Hamvention. We arrived about 8:00 am, just as the gates were opening. The first thing that I did was to head to the FAR Circuits tent, which is–as the name implies–at the far end of the flea market. There, I made my first purchases, a board to make a regenerative receiver and one to make an audio breakout box.

The rest of the day was a combination of wandering the aisles of the flea market, fighting the crowds inside the arena, attending the odd seminar, and meeting people that I know. One of the guys I ran into was Dennis, KT8K. He asked me what I thought was this year’s flea market “theme.” Every year, he says, there is always an abundance of one type of equipment or model of radio.

He’s right, too. One year, for example, I saw a dozen or more Icom IC-735s. This year, I saw none. Oddly enough, this year I saw a lot of Swan transceivers and DX-60 transmitters. There were also lots of more modern transceivers for sale, too. I even saw a K3 for sale, although by the time I got to it, it had been sold.

Another fellow that I ran into was Ed, N4EDT. I probably wouldn’t have stopped to speak to him, but he was wearing a shirt with the Rotarians on Amateur Radio (ROAR) logo on it. I introduced myself to him, and we had an interesting discussion about what kind of service project that ROAR might want to start. Since he is the Assistant Director for Education for the ARRL’s Southeastern Division, he was advocating a local project. I, on the other hand, still favor an international project that would promote amateur radio in a developing country. We also talked about possibly having a ROAR booth at Dayton next year.

By the time, 4:30 pm rolled around, I was pretty hot and tired. Temperatures topped 80 degrees, and on the blacktop surface of the flea market, temperatures were undoubtedly higher. I was happy to get on the bus and head back to the hotel.

Saturday, was pretty much the same story, except it was even hotter. The temperature almost hit 90 degrees. I didn’t bring any sunscreen, either, so I got a little rosy.

I ran into some people that I knew that had just come down for the day, or perhaps that I’d missed the day before. One guy I ran into at the Ohio Repeater Council booth, pulled out his new Elecraft KX-3 and gave me a quick demo. It’s actually quite a cool, little radio. I’m still saving up for a K-3, though.

One forum that I attended on Saturday was the Drake forum. The room was packed with people still keeping alive their old Drake equipment. The reason that I attended was I have a friend who recently was given some Drake C-Line equipment. He wants to find a good home for them. After attending this forum, I’m now thinking about buying it from him and using them in my station. I know that if I ever have any trouble, I’ll have plenty of guys out there who can help me.

After the Drake forum, I went to the food court for a slice of pizza and a glass of beer. Seating is catch as catch can, so I shared a table with several other hams. This is great because you get to meet all kinds of different people.

This year, an older gentleman sat down next to me with his beer. We got to chatting, and as it turned out, this was his 55th straight year attending the Dayton Hamvention! He started going before it was even held at Hara Arena, and even after they moved to Hara, they didn’t use the entire facility as they do now. I’m really glad that I got to speak with him.

So, what did you buy?
I didn’t really go down to Dayton with much of a shopping list. My short list included more PowerPole connectors, the circuits boards I mentioned earlier, and I was going to buy a mic boom for WA2HOM. I got the connectors and circuit boards, but decided against the boom.

I did pick up a bunch of other little stuff including some strain reliefs, more clamp-on ferrite cores, a paddle pad from Vibroplex ($1) to keep the paddle down at the museum from sliding around, and some tube sockets! One of the vendors there had a box of tube sockets that they were selling for a quarter apiece or five for a dollar. I picked out five and paid the lady, and as I was walking away, I decided that they were such a good deal that I went back and bought five more.

My biggest purchase was NT7S’s OpenBeacon QRSS transmitter. It cost me $40. It looks like a very nice kit, and I’m hoping to be on 30m QRSS shortly with it. The nice thing about this transmitter is that it has a microcontroller that lets it transmit DFCW and Hellschreiber, in addition to CW. It should be fun to both build and operate.

I almost bought a K3. I stopped by the Elecraft booth and picked up an order sheet, but decided against it. If they had been offering more than a $50 show discount (<2%), I might have gone for it, but that just wasn’t enough incentive.

Too rich for my blood
In other news, both Kenwood and FlexRadio both introduced new radios at Dayton. Perhaps the most buzz was around the Kenwood TS-990. Of course, they didn’t really have a working model. There’s not even any information on the Kenwood USA website.

What they did have was a mockup under a Plexiglass cover. In addition to being incredibly expensive, the radio is huge! I heard someone joke that to produce this radio, Kenwood is going to have to corner the market on buttons and knobs. If you’ve seen the photo in QST (which was allegedly produced with Photoshop), you’ll know what I mean.

The other radio with a bit of buzz is the new FlexRadio FLEX-6000. For the past couple of weeks, the FlexRadio website was proclaiming that this radio was going to be a game changer. Perhaps it is, but at $6,000+, this radio is out of my league, and too expensive for the majority of radio amateurs. That being the case, I really don’t know what all the buzz is about.

I’m sure that the TS-990 and the FLEX-6000 are both great radios, but I think that the law of diminishing returns applies here. At some point, are you really getting $6,000 or $12,000 of fun out of the radio? I don’t think that I would.

Well, that’s it. Another Dayton Hamvention is in the bag. It was a lot of fun, and I’m already looking forward to next year. In addition to possibly participating with other Rotary Club members in a ROAR booth, I’m thinking about pushing for an adult education forum. I think that’s something that’s both needed and would be popular. I’ll just have to make sure to leave enough time to hit the flea market and grab some more tube sockets or coax or whatever.