The Dummy Load. October 2009 Newsletter

Transcription

1 The Dummy Load October 2009 Newsletter In this Issue Volunteer Examiners 1 Monthly Meeting: Fri Oct 9, 11:30AM at Friday Harbor Firehouse VE Testing: Sat Oct 10, 11:30 AM Friday Harbor Firehouse Safety Fair at Fire Station 1 RMS Packet Station 2 Field Day Beam II 3 Amateur Radio News 5 Dummy Load Copyright SJCARS Editor N Lindenberg KD7IRD nrlindenberg@ rockisland.com Distribution D Hoyer KE7TLE KE7TLE@ arrl.net VOLUNTEER EXAMINERS KEEP IT ALL GOING Next Friday, Oct. 9, Dave Vandaveer will conduct his umpteenth Volunteer Exam session, providing testing and certification for new amateur radio candidates. In our archives, we have clippings as far back as the year They reveal that Dave, John Deeds, Charlie Lindenberg, Mike Speece, Dick Morrison, Mike Sear, and Dick Rich, as well as other qualified examiners, have donated many hours to help new amateurs get their licenses. Our club was even teaching classes for 11 consecutive Wednesday nights! Fortunately for all, the classes are available online, and studying can now be done at home. Want to upgrade? Just check out for more information. SAFETY FAIR at MULLIS FIRE STATION Saturday, Oct. 10; 11:00 A.M. to 2:00 P.M. This unique family event will be bigger and better this year. The planning committee met on Sept. 16, and expects an airlift demo, a crash rescue demonstration of the jaws of life, lots of hands-on activities for children, expanded parking, good food, and plenty of up-to-date information for parents. Last year, more than 300 attended, and we picked up several friends including Heather Cain, KF7BRZ, who came to our meetings, studied, and passed her Tech exam! At least ten community groups and agencies, in addition to the Fire Departments, will have displays, activities and prizes for children at the Safety Fair. Last year, SJCARS hams had a table display, a code key, and tours of the EOC radio room. We ll have a question or an activity for the children, after which they get a sticker for their Passport to Safety. This year, we ll also have the White Box to explain Page 1

2 Safety Fair, Cont d: and celebrate. The American Red Cross will have two nurses on hand to explain the strategies we need to avoid or control the H1N1 flu virus. OPALCO will have speakers to explain the hazards of live wires. And of course there ll be lots of Fire Drill and Fire Plan advice from the fire fighters. The Rescue Demonstration takes place at 12:00 noon. We ll be at our table and needing volunteers for about half-hour shifts, between 11:00 and 2:00. Any more ideas for our display?? Set-up will be on Friday, Oct. 9, all day. Sign up at the next monthly meeting, or call Nancy, What is an RMS Packet Station and Why Do We Need One? P McCorison, K2SPR Most of us rely on for a large part of our brief communication needs. We rarely think about how that gets to its destination except when we have some kind of internet interruption. That happens when our internet service goes down for some reason or for no apparent reason. Wouldn't it be great to have a facility to send our s by radio when the internet is down? Sure it would, but first lets talk about what we mean by "internet down." Well that's simple, you say: its when I can't send s or browse the web. Not so simple, I say, since the internet is a complex chain of connections, the loss of any of which stops our and causes us to say the "internet is down." The internet is pretty good at automatically routing around failures, but a failure here in the county, where we only have one primary internet pipe to the rest of the world truly puts us out of business. For emergency related traffic, we have a couple of ways to workaround this kind of failure. This is where the RMS Packet station comes in. An RMS packet station is an interface between amateur radio and the internet. Using an RMS station, we can bridge the gap between a local failure of the internet and the larger internet world. For example if we put such a station at the EOC at the Mullis Street fire station, we can, using vhf radio and our computers, send our s to that RMS station from, say Eastsound fire station, where the internet is down out to the state EOC, or any other destination on the internet. Thus we have bridged a local gap in internet coverage. But, you say, how does this work when the county's primary internet coverage is entirely down? Of course, if the entire county is down, we have to rely on other means, which we'll see later. However, because of our services in handling emergency traffic, we have access to a special internet pipe set up by OPALCO and paralleling their transmission lines. This pipe is separate from the services supplied by Century Tel and other carriers in the county in that it connects without switching stations direct to a primary internet service provider in Bellingham. This pipe, then, is much more robust than your usual local internet service. If, however, even the robust internet connection is unavailable, we can still get our messages to distant internet gateways using hf radio. Using the Pactor capabilities of the "White Box" emergency stations at Mullis or Eastsound, we can contact gateways from HF Page 2

3 to the internet almost anywhere in the world. So, if we have an RMS packet station in the county, we truly can get the message through "when All Else Fails." Here's what we'll need to put an RMS Packet station at the Mullis EOC PC Free-$500 Radio - Alinco DR-235 $150-$270 TNC - Kantronics /TNCX $100-$200 Feedline - LMR400 $150 Antenna - Comet/Hustler $180 Total about $600 to $1300 To access the station you ll need a 220MHz radio and TNC as well as a computer. AVAILABLE FOR FREE Heathkit HWP Meter Transceiver SSB CW Fixed or Mobile Contact: T. Leche, KE7KRR or mjed13@rockisland.com A Field Day Beam, Part 2 Ed K, KD7TUN Last month I presented some of the technical design details of my 10M/6M beam for field day. This month, I will delve into the construction. Maybe there will be an idea or two in here for your own homebrew antenna. To refresh your memory, the beam was two 2-element Yagis combined, with the 6M driven element parasitically coupled to the 10M driven element. Viewed from the top, it looked like: 10M reflector: 204.4" 6M reflector: 116.4" 6M driven element: M driven element: With a design in hand which modeled nicely, the next step was to actually build one. One rule of successful modeling is to model what you can build, and then build what you have modeled, at least as closely as possible. So, I needed to use 3/8" O.D. tubing for all the elements, and have an insulating boom. I had some other criteria also: 1. The materials should all be available on the Island. 2. The antenna should break down into pieces not much longer than 6 feet. 3. It should go together and come apart quickly. 4. It does NOT have to survive 50mph winds, or last for 5 years in the rain. For the tubing, I selected the green plant stakes available from Browne Lumber and Ace. They look and feel like fiberglass, but are in fact plastic coated steel tubing, 3/8" O.D. tubing with a 0.010" wall, to be exact. They can be had in 6' lengths, just right for criterion #2. The 10M elements are both a little less than 18' long, so three lengths will make one element. And the 6M elements are a little less than 12' long, so two lengths each will do the job. But how to join them? I considered machining threaded fittings to press into the ends, but that looked like a lot of work for a "quickie" antenna. I decided to try making the tubing sort of plug together and stay that way with spring pressure. I stripped about 1" of plastic off one end, and Page 3

4 then split it with a 1/16" cut-off wheel in my die grinder. It looked like: With the split, it could fairly easily be plugged into the end of another piece of tubing, and seemed to be pretty securely held in place. I chose 1" PVC schedule 40 pipe for the boom, and decided to mount the elements by simply drilling a hole through the pipe at the appropriate spacings taken from the model. The 10M driven element was supposed to be 77.4" from the reflector, so the overall boom length would meet criterion #2. A 15/32" hole proved to be a perfect fit for the garden stakes, and for some unknown reason I actually had a drill of that size in my tool box. But how to keep the tubing in place? I tried fiddling with rubber bands, considered screws, or bubble gum, and finally settled on rolling a small O-ring onto the tubing on each side of an element: could just be screwed on. Of course, it would have to bottom out exactly right, with the driven element parallel to all the others. To give some freedom of adjustment but still have the plug fairly tight, I added an O-ring around the plug. That allowed me to tighten the plug up against the O-ring, and still be able to set the angle properly. To make the split element, I used a piece of fiberglass rod which snugly fit inside the garden stakes and supported the two halves, while insulating them from each other. The rod is the only thing I didn't buy on the Island - it's a piece of rod for a chimney sweep setup, purchased from Hardware Sales in Bellingham. The coax connector mounted nicely to one of the flats on the plug with two screws, and a little braid, tinned and punched for screw holes, connected it to the driven element. Now to the messy part - how to make the center section of the driven element. It needed to be split at the center and connected to a coax connector. Clearly, that mess wasn't going to gracefully go through a hole in the PVC boom. I decided to permanently attach everything to a threaded PVC pipe plug. With a matching threaded adapter glued on the end of the boom, the driven element The final problem was how to mount the boom to a mast. I wanted to use a 12' fiberglass paint roller extension that I got from Ace. (It telescopes to about 6' long, so it also meets criterion #2.) I made a crude tap from the discarded end of a threaded broom han- Page 4

5 dle, and drilled and tapped a piece of 2X2 for the standard paint roller/broom handle threads. With a couple of screws to attach the 2X2 to the boom, I can just screw the antenna onto any paint roller extension I have handy. When I propped up the antenna on the extension pole in my driveway, two things became immediately apparent: 1) the model was dead nuts on - resonances were right where they were supposed to be, with nice low SWRs, and 2) the plug-together joints lacked something in strength. The worst case was the 10M reflector, due to the long ends. I strengthened them by inserting a piece of the same fiberglass rod, turned down in the center so that the slit tubing had room to crush. After a few mishaps in the field, it is obvious that this same reinforcement is needed at all the other joints. What happened on Field Day was that someone would try to rotate the antenna and inadvertently unlock the telescoping paint roller. The antenna would then drop 6', stopping suddenly at the bottom, stressing the heck out of the joints, and making the antenna look pretty pathetic. Other than that one weakness, it appears to be a success. AMATEUR RADIO NEWS National Weather Service HF Radio is coming to NWS Seattle. The radio arrived at the end of August and will be installed and operational soon. HF joins the current suite of radios including VHF, UHF, 800 MHz and the state CemNet Radio. The amateur radio team led by Brian Daly WB7OML, and NWS Seattle forecaster and amateur radio program manager Jeff Michalski, are working to enhance NWS Seattle WX7SEA amateur radio workstation operations. For instance, they are working on re-establishing the packet radio system that will permit a number of NWS Seattle forecast office products to be posted on bulletin boards throughout western Washington. And as a reminder, NWS Seattle has permission to use the K7PP repeater system that has service throughout much of western Washington at MHz. The K7PP repeater system is undergoing an upgrade. NWS Seattle can use the system during significant weather events, other hazardous events like a major earthquake, exercises and special events like the Skywarn Recognition Day event coming up on the first Saturday of December. We hope you can join us for this annual event again this year. Several amateurs that live close to the forecast office can join our forecast operations by working the amateur radio workstation during such events in support of the NWS Seattle mission. Reprinted by permission, National Weather Service, So, here's the message: Go to Browne's, go to Ace - there are antennas lurking there in the garden department, or the paint depart- Page 5

6 The San Juan County ARES Nets Every Wednesday Local Time 19:00 - SSB Net 3944 KHz +/- QRM 19:30 - CW Net 3555 KHz Check in! Take the Callsign Challenge 20:00 - VHF Net MHz, -600 KHz offset, tone , +5 MHz offset, tone In the event of repeater problems we shift to: First: Repeater Output MHz simplex, tone Second: TAC MHz simplex, tone White Box Drills every Tuesday, 9:30 A.M. at a White Box near you! Net Control Schedule Please arrange a substitute if needed Sept 30 Howard R, N7FBC Oct 07 Charlie L, W7BXH Oct 14 Ed K, KD7TUN Oct 21 Monty M, N7TAU\ Oct 28 Jim M, K2SON Nov 04 Ted L, KE7KRR Nov 11 Nancy L, KD7IRD Nov 18 Dani H, KE7TLE Nov 25 Clare K, KE7WQY October 9 Upcoming Events Monthly Meeting 11:30 A.M. Friday Harbor Firehouse October 10 V E Ham Testing: 11:30 A.M. Friday Harbor Firehouse October 10 SAFETY FAIR, Mullis Fire House, Amateur Radio table 11:00 2:00 Oct 17 FIELD TRIP?? The Dummy Load c/o Nancy Lindenberg PO Box 1513 Friday Harbor, WA First Class Mail Page 6