2 Meter Halo Antenna - KR1ST

A Tree Friendly 2 Meter Halo Antenna Having purchased an all-mode, all-band (160m - 70cm) transceiver, I became curious about what 2-meter weak signal operations have to offer. I have a 5/8th over 5/8th vertical collinear antenna hanging in a tree at some 30 odd feet high, but I never heard anything on it, except on FM. The reason for that, I learned, is most 2-meter weak signal operations take place using horizontal polarization. Cross polarization is good for about 20 dB attenuation, which easily translates into the difference between perfectly good copy and inaudible signals. So I decided I needed a horizontal polarized antenna. As is usually the case with antennas, there are a bazillion designs to choose from and none of them really fulfills all your requirements. I do not have a mast or tower, and I love to use trees for supports, so I wanted something that I could hang from a tree branch. Since I have no means to rotate the antenna, I required that the new antenna have an omnidirectional radiation pattern. It didn't have to be the best performer, because I just wanted to get my feet wet in this new mode of operation. There are few designs that would fit that bill. I settled on the Halo antenna because of its small footprint. This is important because larger designs would require a longer branch, with sufficient clearance in all directions, to hang from. The Halo I describe here has a diameter of only about 12 inches and can be hung virtually anywhere in a tree. The Halo Antenna Halo stands for "HAlf wave LOop". The antenna is in fact nothing else but a half wavelength dipole with the legs bent in the shape of a circle. However, the ends do not meet, (especially near the end of the month) so technically it's not a loop. This loop can be fed with coaxial cable using a gamma match. The Halo is certainly not a new design. Laurence M. Leeds and Marvel W. Scheldorf obtained a patent for this antenna in 1943. You can find their design at the U.S. Patent Office under Patent Number 2324462. Click on the "Images"-button to view the patent. You'll need a special browser plugin to access the patent. See the U.S. Patent Office website for more information on this. Most Halo designs you find on the internet have moving parts. Often they require some sort of tuning capacitor and have a capacitor in the gamma match along with a slider construction that connects the gamma arm to the radiator. I prefer a design without moving parts so that the antenna doesn't get detuned easily when a bird decides the antenna makes a good resting place. I found the design that I describe here in a German antenna book "Antennen Buch" by Karl Rothammel, Y21BK. Basic Design The design of this antenna is very simple and straightforward. It basically consists of a half wavelength piece of copper tubing bent into a circle. Between the ends of the tube there needs to be a gap of at least 1 3/16". This is to minimize capacitive coupling between the ends. This antenna is fed by a coax feed line through a gamma match. The gamma match is constructed from 6 1/4" #4 or #6 copper wire. This wire is bent into an L shape. The short end of the wire is soldered on the inside of the loop at the point where the long end of the gamma arm aligns with the halfway point of the loop. See below:

You could feed the loop directly with 50 ohm coaxial cable as shown above. However, I added a 1:1 current balun (choke) to the original design. I did this to force all the RF current, on the inside of the braid of the coax feed line, to go into the antenna and not to come back down on the feed line on the outside of the coax braid. This will help keep the feed line from radiating, causing potential RFI problems and changing the radiation pattern of the antenna. Building the Halo Building this antenna is like making the pieces of the puzzle first, and then putting the puzzle together. First you build the antenna itself, then the support boom, the choke balun, the mount, and finally, you put these parts together. The Antenna Start out by cutting a string to a length of 41 inches. You'll use this to measure the correct tube length. Thick monofilament wire as used for garden trimmers works very well. Mark this wire at the halfway point. A piece of electrical tape will do fine. This is the point where you’ll later have to mark the copper tube and where the coax braid will get soldered to the tube. You'll probably find the soft copper tubing material in a 10-foot length, coiled up in a bag. Fortunately, the coil diameter is about the same diameter as the final loop will be. So there will be very little bending involved to get the circle shape needed for the loop. Eyeball how much tube you'll need from the loop coil and cut it. Don't attempt to make an exact measurement yet. In fact, the measurement I give here for the main loop is deliberately somewhat too large anyhow. Put the part you cut off on a flat surface and now measure how much you really need using the string from the previous paragraph. Cut off the excess tubing. Use the string again to find the halfway point of the tubing and mark it. This will be the point at which you will later solder the coax braid. Make sure the tubing is shaped like a circle, and that the ends are at least 1 3/16" apart. To keep the ends apart, I cut a piece of hexagonal Bic pen tubing to length and put it between the ends. You can secure it with some shrink tubing, but don't shrink it until you're done with the final tuning later on.

Now build the gamma from a piece of #6 or #4 copper wire. Use the measurements from the detail diagram above and bend it as shown. Solder the short end of the gamma arm to the inside of the loop at the point where the long end of the gamma arm lines up with the halfway point on the main loop (as marked earlier). The Support Boom To support the antenna, I used a piece of 3/4" schedule 40 PVC pipe. Lay the antenna on the pipe and cut it so it's just a bit longer than the diameter of the loop. Now drill holes through the pipe to mount the antenna. On one end of the pipe you need two holes approximately 1 15/16" apart for the main loop and the gamma match to go through. Make sure you drill the hole for the tube very close to the end of the PVC pipe. This will make it easier to solder the coax braid onto the copper tube. Also be careful not to drill the hole for the gamma match all the way through the pipe. The gamma match only goes in halfway through the pipe and will not come out the other side. On the other side of the PVC pipe, drill a hole in the same plane as the first two holes for the piece of plastic tubing (hexagonal Bic pen) that is being used to keep the ends of the main loop apart. Next, drill the holes necessary to mount the SO-239 (panel mount) connector. The last hole you need to drill is for mounting purposes. This hole needs to be drilled in the middle of the PVC pipe, all the way through. Make absolutely sure that this hole is perpendicular to the plane of the antenna. This hole needs to be the size of a bamboo skewer you can buy at the grocery store (sold in a bag of 20 or so). This skewer is later used to mount the antenna. You can use something else if you like as long as it's thin, strong, sturdy and straight.

The Balun Even though the original design does not call for a balun, I decided to add a 1:1 current balun in order to prevent RF currents from flowing back onto the outside of the coax braid, perhaps causing the feed line to radiate, create interference and change the radiation pattern of the antenna. The balun I built for this antenna consists of 12, 1/2" long, type 43 ferrite beads that slide over a short piece of RG-58 coax with the outer jacket removed. The hole in the beads I used was not big enough for the coax to slide through with the outer jacket intact. The length of the piece of coax needed for the choke can be measured from the end of the boom where the gamma match is to the farthest edge of the SO-239 connector, plus about 3/4". The balun itself is about 6 inches long. If you use a different size of beads, just make sure you have enough beads to make a 6-inch long balun. You can secure the beads with some shrink tubing or electrical tape. This should be enough to make an effective balun for VHF that can handle up to 100 Watts of power. One side of the coax should be prepared so you can solder it to the SO-239 connector. You can already solder the connector to the coax if you wish. The other side needs to be prepared so that the braid will reach the middle of the loop, and the center conductor meets the gamma match. Do not cut the center conductor to length. Instead, only remove the insulation from the center conductor so that it can be soldered later to the gamma match. Leave the excess wire intact. Put some shrink tubing or electrical tape around the braid to insulate it, except for the very end, of course. If you do not have any ferrite beads available, you can construct an air core choke balun instead. There are several ways to make one. One method is to wind about 7 turns of the feed line on a coil form made from 3/4" PVC pipe. Place this choke near the antenna. If you prefer the choke to be part of the antenna, then you can wind 7 turns of the coax going from the SO-239 connector to the gamma match around the PVC boom. The Mount Since I've chosen to hang this halo from a tree branch, I needed to find a way to mount this antenna onto a rope coming down from a branch in such a way that the antenna itself will remain in the horizontal plane. I came up with a method that will use gravity to hold the antenna perfectly horizontal. When you built the PVC boom, you drilled a hole in the middle for a skewer. Now imagine you put the skewer through the boom, put the support rope alongside of the skewer and then tie the rope to the skewer with some wire ties. If you'd hold just the rope above the skewer and boom, the boom would just dangle in all kinds of directions and stay far from being horizontal. However, if you'd make a small loop in the bottom end of the rope and hang a weight from it, you'll see that the boom stays perfectly horizontal. See the diagram below.

Putting It All Together Take a piece of pen tubing, or whatever you chose to fill the gap in the main loop, and push it in the PVC boom. Next you can join the antenna with the boom. Take one end of the antenna and guide it through the hole next to the hole for the gamma match in the PVC boom. Slowly move the tubing through the PVC support pipe. You'll notice some resistance because the loop is round and the holes through the pipe are in a straight line. This causes some friction. With a small amount of force you'll see that that the tube will go through the pipe quite easily. Stop when you reach the gamma match. Do not push the gamma match into its hole in the boom yet. Bend the end of the braid of the coax that goes inside the boom at a 90-degree angle. Just over 1/4" from the end should be sufficient. This will make it easier later on when you solder the braid to the tube. Also bend the exposed center conductor at a 90-degree angle about 1/4" from the end. Slide the coax inside the PVC boom through the hole for the SO-239 connector. While you do this make sure that the end of the center conductor kind of scrapes on the inside wall of the pipe, on the side where the hole for the gamma match is located. At some point you'll notice that the wire will get caught in this hole. Pull the wire through the hole with needle nose pliers while you continue to slide the coax inside the pipe. Stop when the insulation around the center conductor appears at or through the hole. If you bend the wire a bit at this point, it will stay in place. Solder the center conductor to the gamma arm. You can cut off the excess wire, but I simply bent the remaining wire along the gamma match. Or, wind it around the gamma match, just in case you have to do it again. Now slowly push the gamma arm in the hole of the PVC boom. If it doesn't quite fit, you can cut a tiny wedge out of the hole where the center conductor passes through the hole. Stop when the gamma match reaches the middle of the pipe and the center marking on the copper tubing is in the middle of the PVC pipe. When you look into the pipe you'll see the braid near the copper tube on the inside of the pipe. Pre-tin the copper tubing at the halfway mark. Make sure this mark is in the middle of the pipe. Now you can solder the braid to the tube.

If you haven't already soldered the SO-239 connector to the coax, then do so now. Push the remaining coax into the boom and fasten the SO-239 connector to the boom. Slide a piece of shrink tubing over each end of the antenna. Mate each end of the copper tube with the piece of pen tubing protruding from the support boom and slide the shrink tubing back a bit so it covers the piece of plastic tubing also. Do not heat the shrink tubing yet. This will hold the ends in place. You can also use electrical tape to do this. Just make sure the ends of the copper tubing stay flush with the plastic tube.

Mounting the Antenna The antenna is now finished and we're ready to mount it for testing and tuning. Find a place where you can hang the support rope, like a tree branch. Make sure that there are no metal objects nearby, as they will detune the antenna. You can tune the antenna at a different place than the final destination if you wish. Put a wire tie just below the middle of the skewer. This will prevent the antenna from sliding down the skewer. Secure the bottom half of the skewer onto the rope with two or three small wire ties. Make sure the skewer cannot slide along the rope. Drop the bottom end of the rope through the loop of the antenna and push the skewer all the way through the support boom from the bottom up. You may have to wiggle it a little bit when you're halfway into the pipe in order to get past the coax inside. Once the skewer is all the way through the support boom and the boom is resting on the wire tie on the middle of the skewer, you can fasten the top half of the skewer to the rope with two or three wire ties.

Your antenna can now dangle freely from the rope. You'll see that the antenna does not really stay horizontal yet. Make a small loop at the bottom end of the support rope and hang a weight from it. I used a brick. Even if the antenna is going to be mounted very high up in a tree, try to keep the weight near ground level. This serves two purposes. First, if for some reason the weight would fall, it will not fall on top of someone and no one will run into it. Second, it will keep the whole system very stable in the wind. If the weight would be higher than just a few feet of the ground, the wind would catch it also and start swaying the weight. Not only is this dangerous, it will also take a long time before the system is stable again once the wind drops. Of course you could opt not to use a weight and simply tie the bottom of the rope down. However, that makes the whole mechanical system very inflexible. The rope would move back and forth over the branch when it's swaying in the wind, and eventually the branch might be cut. If you later find that the rope and weight are swaying too much, you can minimize this with a guide rope that is tied to, say, a post, or the trunk of the tree, and goes around the support rope. The guide rope will then allow the support rope to move mainly in the vertical direction. Once finished, the antenna should look something like this:

Testing and Tuning Before you test the antenna, double check you made all the right connections. When you use an ohmmeter to check the connections, you should be measuring a short (zero ohm resistance) between the center and outer connections of the SO-239 connector. This antenna is what is called "DC grounded", which may help reducing static buildup on the antenna. Now you can attach a 50-ohm coaxial feed line to the antenna to test and tune it. Use a wire tie to attach the feed line to the skewer. This will make the feed line run along the support rope and help stabilize the system. If you plan on weatherproofing the antenna, then read the part on weatherproofing below first before you tune the antenna. I borrowed an antenna analyzer to tune the antenna, but you can also do it with just an SWR meter. When you use an SWR meter and cannot find a near 1:1 SWR anywhere in the 2 meter band, you need to make note of three SWR measurements. One at 144 MHz, one at 146 MHz and one at 148 MHz. If you find that the SWR is lower at 144 than at 146 and 148 MHz, then you know the antenna is tuned below the 2-meter band. If you find that the SWR is lower at 148 than at 146 and 144 MHz, then you know the antenna is tuned above the 2-meter band. You will probably find that the antenna is tuned somewhat below the 2 meter band. I deliberately listed the measurement of the main loop slightly too large which results in a lower than desired resonance frequency. Cut a tiny bit of each end of the copper loop until your antenna resonates near 144.200 MHz. That is the SSB calling frequency in the U.S.A. Of course you'll have to decide at which frequency you want the antenna to be resonant. The 1:1.5 SWR bandwidth of the antenna is about 1 MHz. Since the gamma match is fixed, you will probably not be able to get an exact 1:1 SWR reading. More realistic is 1:1.1 to 1:1.3. Don’t let this scare you. SWR readings other than 1:1 are perfectly fine as long as they do not go much higher than 1:1.5. At that point many rigs will throttle back the power. If you really cannot sleep peacefully if the SWR isn't perfectly flat, then by all means desolder the gamma match from the loop and solder it at a different point until you've found that serene 1:1 SWR spot. I will warn you though that things can get messy real quick while it really isn't worth the effort. If you find yourself in the position where you cut too much of the antenna ends in order to find that elusive 1:1 SWR, don't panic! There's an easy solution. Solder a half inch or so piece of solid copper wire (#14 will do) to the inside of each tube end as shown in second diagram on this page. The wire ends protruding from the copper tubing will fit inside the plastic separator tube. This will help maintain a clean look of the antenna while you get a second chance at tuning the antenna. Now simply cut small pieces, like 1/16" or so each time, off of each wire until the antenna resonates at the desired frequency. When the antenna is tuned you can heat up the shrink tubing around the copper tube ends so that everything remains in place. Weather Proofing You can weather proof the antenna by filling all holes and gaps with RTV, or silicone sealant. Care should be taken when you want to seal the end of the boom where the ends of the loop meet. Putting RTV in that side of the pipe will detune the antenna. Make sure the sealant only goes to the inside of the PVC tube, and don't be tempted to put any sealant on the loop ends. The reason for this is that there is some stray capacitance between the loop ends. By adding sealant you change the dielectric between the tube ends, and therefore the value of the stray capacitance. This in turn changes the resonant frequency of the antenna. So it is better to seal this end of the support boom first before tuning the antenna if you plan on weather proofing the antenna. If you feel that you need to seal the area around the small piece of spreader tubing, then use something like a very thin layer of nail polish. Also, if you want to make the loop very shiny, use some very fine steel wool to polish it. Conclusion I described how you can build a Halo antenna for two meters that does not require a mast, has a very low part count and can easily be built with a minimum of tools. This project description may seem more complex than similar ones you can find on the internet, but that is simply because most other plans leave out a great deal of detail, especially in the area of construction. I like to include the lessons I learned along the way when I built the antenna. This article also described a unique way to mount these types of antennas on a rope. This makes the antenna an attractive alternative for use in the field where the usual support structures may not be available or for those folks who, like me, do not have a tower or mast. Of course you can mount the antenna on a mast with a U-bolt if you wish. I have built a 2 and 6 meter version of this antenna, mounted them on the same support rope and feed them with separate feed lines.

The 2 meter Halo is mounted at 24 feet, and the 6 meter Halo is mounted at 20 feet high. As you can see, the Halo makes for a stealthy antenna even though that was never one of the design goals. If you really want the antenna to blend in with the background, paint it light gray or light green, and add some random black strokes here and there. When you break up any symmetrical lines and patterns, any object can be made invisible against the background. These Halo antennas allow me to dabble a bit in VHF weak signal operations given the restrictions mentioned in the beginning of this article. While the performance of this type of antenna is limited compared to other types of antennas, I'm rather surprised with the DX contacts I’ve been able to make with a modest 50 Watts of power. If you have any questions or suggestions, please do not hesitate to drop me an email.

73, --Alex, KR1ST

Miracle Whip Antenna

Alan - You aren't missing anything. The Miracle Whip is an inefficient antenna. It will not do better than your short piece of wire hooked to an antenna tuner. It will probably do worse. The only miracle is that they can sell it for such a high price.

For short antennas, the radiation resistance of an antenna decreases as the square of the length. So an antenna that is half as long will have a quarter the radiation resistance. As the radiation resistaance goes down it starts to be comparable, or less than the loss resistances, so much of the power input to the antenna is dissipated in the loss resistances and the efficiency goes down. Way down.

The SWR is low in large part due to the high loss resistance of the antenna.

It is not the current as such that does the work in an antenna, but rather the sinusoidal motion of the individual electrons in the antenna wire that cause time varying electric fields in space and hence electromagnetic radiation.

Someone in G land, whom I think is on this list, has plans for a homebrew "Miracle Whip". At least he admits it is an inefficient antenna, unlike hte commercial version. If you want to experiment with this inefficient antenna, I suggest that you try the homebrew model nand save yourself a bundle.

For short antennas, give the PAC-12. With a modest ground, it will outperform the Miracle Whip.

Dr. Megaacycle KK6MC/5
James R. Duffey KK6MC/5
Cedar Crest NM 87008 DM65

Ham Jokes

YOU MIGHT BE A HAM IF........
1. YOUR WIFE SAID "LETS GO SEE AUNT ANNA AND YOU THOUGHT SHE SAID ANTENNA!

2. YOUR WIFE SAID "COULD YOU CUT THE GRASS?" AND YOU THOUGHT SHE SAIDPOUND THE BRASS!

3. YOUR WIFE SAID "WE'VE BEEN INVITED TO BREAKFAST AND YOU THOUGHT SHESAID HAM FEST!

4. YOUR WIFE SAID "SOMETHING IS WRONG WITH THE CHECK BOOK AND YOU THOUGHT SHE SAID LOG BOOK!

5. YOUR WIFE SAID "IS MY SEAM STRAIGHT? AND YOU THOUGHT SHE SAID, " IS MYBEAM STRAIGHT?'

A HAM NAMED ELMER LIVED WITH HIS XYL NAMED SUE. WHILE AT THE QTH ONE NIGHT, SUE SUDDENLY WENT QRT. (DIED). ELMER PICKED UP THE PHONE, AND CALLED 911 AND REPORTED THAT HIS WIFE HAD JUST DIED AND COULD SOMEONE COME OVER TO PICK HER UP. THE OPERATOR ASKED FOR HIS ADDRESS AND ELMER SAID HE LIVED ON THE END OF EUCALYPTUS LANE...SHE ASKED HIM TO SPELL THAT. THERE WAS A LONG PAUSE ON THE END OF THE LINE AND THEN ELMER SAID. "HOW ABOUT I JUST DRAG HER OVER TO OAK STREET AND YOU MEET ME THERE"!!
HEARD ON 2O METERS

"Yesterday, my XYL said she'd leave me if I didn't give up ham radio.Over."Two elderly hams had been friends for many decades. Over the years they had shared all kinds of activities and adventures on the ham bands. Lately, their activities have been limited to meeting a few times a week to play cards. One day they were playing cards when one looked at the other and said, "Now don't get mad at me.....I know we've been friends for a long time.....but I just can't think of your name and your call.! I've thought and thought, but I can't remember them. Please tell me what they are." His friend glared at him. For at least three minutes he just stared and glared at the gray haired old man.. Finally he said, "How soon do you need to know?

An elderly ham and his XYL were on a cruise and it was really stormy. They were standing on the back of the boat watching the moon, when a wave came up and washed the old woman overboard. They searched for days and couldn't find her, so the captain sent the old ham back to shore with the promise that he would notify him as soon as they found something. Three weeks went by and finally the old man got a fax from the boat.

It read:"Sir, sorry to inform you, we found your wife dead at the bottom of the ocean. We hauled her up to the deck and attached to her posterior was an oyster and in it was a pearl worth $50,000 . .please advise" The old man faxed back: "Send me the pearl and re-bait the trap!"

Three brothers ages 92, 94, and 96 live in a house together. One night the 96 year old draws a bath. He puts his foot in and pauses. He yells down the stairs and says "Was I getting in or out?"

The 94 year old yells back "I don't know. I'll come up and see." He starts up the stairs and pauses. Then he yells "Was I going up the stairs or down?"

The 92 year old HAM is sitting in front of his HF rig and listening to his brothers. He shakes his head picks up the mic and says "I sure hope I never get that forgetful." He knocks on wood for good measure. He then yells into the mic, "I'll come up and help both of you as soon as I see who's at the door".

Electricity originates inside clouds. There, it forms into lightning, which is attracted to the Earth by golfers.After entering the ground, the electricity hardens into coal, which, when dug up by power companies and burned in big ovens called 'generators,' turns back into electricity...where it is transformed by TV sets into commercials for beer, which passes through the consumers and back into the ground, thus completing what is known as a "circuit"........Dave Barry

PHILIPPINES HAMS MAY LOOSE 70 CM

Hams in the Philippines are wondering how long it will be before they are ordered off of the 70 centimeter band. This, after that nations National Telecommunications Commission announces the inclusion of all of that band inn spectrum it is considering being made available for broadband wireless networks.

The regulatory agency made the suggestion in a Memorandum titled "Frequency Band Allocations for Broadband Wireless Access." The surprise was the inclusion of 410 to 495MHz in nine bands. This includes the Amateur and Amateur Satellite spectrum including the internationally agreed to allocations.

Jose Mari Gonzalez, DU1JMG, is the Manilla based president of PARA which is the Philippines National Amateur Radio Society. He says that PARA opposes both the memorandum and the potential loss of 70 centimeters. He notes that 430 to 440 MHz includes the international amateur satellite band. He says that if and when the Philippines National Telecommunications Council decides to remove 70 centimeter access from Ham Radio that his organization will file an official complaint to the IARU. This would likely lead to a complaint by the IARU to the International Telecommunications Union that would hopefully warn the NTC not to change the internationally agreed frequency allocations.

For its part, the Philippines National Telecommunications Council says it proposes to reallocate spectrum for broadband wireless networks in line with the thrust of the government to promote and facilitate the development of information and communications technology. Right now only about 5% of the population in The Philippines has access to the Internet, much less broadband, and this is partly due to the lack of infrastructure.

(VK3PC)

Battery Power

From: eudamac3
To: Ray (VU3ORN)
Sent: Wednesday, 13 July, 2005 6:24 AM
Subject: Battery Power

You should be able to do these calculations yourself.Battery capacity is rated in ampere*hours. A substantial car battery is good for 65 AH. That means 65 amps for one hour, or one amp for 65 hours. That's a SIZABLE battery. Some smaller car batteries are but 25-30 amp hours. An old battery can be as poor as 5AH and still start a car, unless the car needs a LOT of cranking. Old batteries are deficient in amp hours. If "mom's old car battery" was replaced because it was not really starting the car reliably, then it's probably way low in amp-hour capacity.

Anyway, here's how the calculations worked for me one year.Rig was a Kenwood - don't remember model, one of the early solid state rigs. This was a "full power" 100W solid state radio.

RX current consumption: 2.5 amps TX current consumption: 22 amps at 100W CW carrier Got those numbers from the owner's manual.

The one added number that would be nice to have is "TX current consumption with no carrier". That's when the radio is in transmit mode, but you're not actually pushing on the key (or speaking into the microphone). For the radio I was using, I measured this value at 5 amps.Then, figure some duty cycles in percent.For hard-core contesting, RX=50%, TX=50%During the transmit time, figure "no carrier" for 50% and "full carrier" for 50% (that's the statistical norm for CW - SSB is actually a bit more gentle on the battery, but we'll figure this conservatively) - that means 50% of the time we're in RX, 25% of the time it's TX no carrier, and 25% of the time TX with full carrier.Multiply the current draw times the % of time that you're drawing that much. Total % must add up to 100%. The number you'll end up with is amp-hours required PER HOUR. Then multiply by # of hours of operation desired.RX: 50% X 2.5 amps = 1.25 amp-hours per hourTX no carrier: 25% X 5 amps = 1.25 amp-hours per hourTX full carrier: 25% X 22 amps = 11 amp-hours per hourTotal here equals 13.5 amp-hours per hour. If we want to run a full 24 hours on Field Day, then it's 24 X 13.5 amp-hours, or 324 amp-hours total required. I would need five large car batteries for my entire weekend of operating. Maybe only four, since I did do this very conservatively (actually spend more than 50% of the time listening, for instance).Now, this was for an FD I did WAY back in 1977. I did not know the actual car battery amp-hour capability. So, here's what I really did. I had a car, and a spare battery. I added "jumper posts" to the car - 1/2" bolts, attached to a phenolic plate, located some distance from the battery, but still under hood. These went in parallel with the cables connecting car battery to alternator. I brought two sets of jumper cables. I drove the car to the FD site, and set up camp. I set the rig up on the spare battery. I removed the "main" battery from the car, setting it on a hunk of wood a few feet from the car, but jumper-cabled back into the car. I then ran the radio until the "spare" battery died. At that time, I started the car (the "main" battery was jumper-cabled in, remember?). I then used the second set of jumpers to attach the "spare" battery to the car. I was careful to make the final connection to the jumper post under hood so the spark did not occurnear the battery. Now I have the car running, with a "full" and "empty" battery connected. I disconnected the "full" (otherwise known as "main") battery, being careful to avoid sparks near the battery. Now, put the "main" battery at the operating station, and go at it. After an hour, shut off the car. Operate until "main" battery dies, and do the car-start/battery-swap routine again. I only had to battery-swap twice.One variable that I did not include - at what terminal voltage does the rig quit operating? Some "full power" HF rigs are famous for insisting on at least 12V, and will shut down quickly below that.Now, just for grins, let's do this again, but use the Elecraft K2 QRP rig. I'll do this thing conservatively again. I picked the K2 only because Elecraft gives more detailed specs and technical data than almost anybody else, and the K2 seems to be used by many contesters, not just QRP operators.RX current consumption 0.25 ampsTX current consumption 2 amps (at 10 watts output)Elecraft's website does not specify the current consumption of the K2 when in TX mode but not transmitting, so I'll dispense with that analysis.RX: 50% X 0.25 amps = 0.125 amp-hours per hourTX: 50% X 2 amps = 1 amp-hour per hourTotal = 1.125 amp-hours per hourFor a 24 hour field day, the total is 27 amp-hours.This should be within the capabilities of a medium-sized car battery in good condition.You could test your car battery, by the way. Charge it fully, and connect an automobile headlight to it, and see how long you go before the battery voltage drops below 11 volts. Most auto headlights have a wattage rating on them. Divide that number by 12 to get the amps draw. For instance, my VW's headlights are marked "60 watts", so they are 5 amps. If my car battery runs them for only 2 hours before the battery voltage is below 11, then I only have 10 amp hours in the battery - which is a pretty dead battery.Assuming a fairly efficient QRP rig, if you only got two hours of operation, this suggests the battery is delivering less than 3 amp hours of capacity. You'd have gotten more lifetime by stringing 8 "D" alkaline cells in series together and it's time to scrap that battery!In fact, I'm quite certain that I can get roughly 6-8 hours out of my 6 watt 2 meter rig, with a heavy amount of transmitting (relaying information for a bicycle race) with a single charge on my 2.2 AH NiMH batteries.It's worth spending $30 to $40 for a brand new car battery, to be kept trickle charging in the garage (never in the house), or maybe $20 for a 7AH sealed lead acid battery.Boy, this is reminding me of the days when I tried to homebrew a battery powered go-kart using old car batteries. I learned very quickly that by the time a car battery seems weak in a car, it's useless for anything else, too.Yeah, get a new battery.Thanks for letting me ramble......FM

Pamban Island Expedition (AS-173) to Rameswaram Town

Pamban Island Expedition (AS-173) to Rameswaram Town
By B. L. Arasu Manohar, VU2URJuly 12, 2005

Rameswaram town is a very old and a historic place of pilgrimage from the times of the Epic Ramayana. The present population is about 38,000, and the daily floating population is many times over. It was earlier connected only by a railway bridge called Pamban Bridge. A 2.2 km long pre-stressed concrete road bridge called Indira Gandhi Bridge, across the sea, parallel to the Railway Bridge, has improved the tourist and pilgrim traffic. There are quite a number of tall towers with three blade type of windmill electric power generating units installed in the coastal area.

A very important landmark in the town is the majestic composite (concrete and steel) type television tower of Doordarshan, over 200 meters tall, prominent in the skyline. The town is located at approximately 79 degrees 22 minutes E, 9 degrees 17 minutes N (Grid Locator MJ99qh), on Pamban Island in the south Indian peninsula, in the Palk Strait/Bay. There are many smaller islands, including Kurusadai, Sangala and Pumarchan, close by, but special permission from the Forest Department is required to visit them.

This area of Palk Bay felt the fury of a cyclone between 17 and 24 December 1964 that devastated the town of Dhanushkodi from where regular steamer service was run to the Sri Lankan port of Talaimannar. The cyclone completed its fury after washing away a passenger train between Rameswaram and Dhanushkodi, killing hundreds of the passengers. This Pamban Island Expedition was dedicated to the memory of all those who lost their lives. The QSL card also has this dedication.

Satellite picture of a portion of the Palk Strait between Mainland India (at left) and Sri Lanka (at right).

The view while proceeding from the mainland to Pamban Island. From the top of the Indira Road Bridge, the left shows a Scherzer type, meter gauge (1000 mm gauge) steel railway bridge, which opens up, as cantilevers, to pass maritime traffic.

The main entrance to the holy temple at Rameswaram, facing the sea. All Indian temples have a gopuram, a tapering square or rectangular structure, seen from long distances, to identify the location of the temple.

The world famous Thousand Pillar corridor of the Temple at Rameswaram.

The group of operators at Pamban Island-Rameswaram Town. Sitting, left to right: OM RamaRaju, VU2RMJ; YL Sarla, VU2SWS; OM Arasu, VU2UR; OM Rajan, VU3WIA; OM Durai, VU2NDR. Standing, left to right: OM Nadan, VU2KGN; OM Vittal, VU2VIT; OM Mandraselvan, VU3RRU; OM Ravi, VU2FBI; OM Guru, VU2GUR; OM Prasad, VU3YFD.

OM Rajan, VU3WIA, handling SSB QSOs and logging by OM Arasu, VU2UR.

OM Prasad, VU3YFD, for all SSTV and PSK31 QSOs.

The banner of the Rameswaram IOTA operation.

Schoolchildren listening to the talks at the demonstration, with others seated.

Top left: District Collector Mr Sellamuthu IAS, and DIG of Police Mr Alexander Mohan IPS, as the chief guests in the demonstration. OM Arasu, VU2UR, addressing the gathering. Top right: OM Rajan, VU3WIA, addressing in simple Tamil to all the children and general public. Bottom left: OM Vittal, VU2VIT, presenting a Kenwood Amateur Radio Map of the World to the District Collector, for the Ramanathapuram Amateur Wireless Association. Bottom right: Mr Alexander Mohan IPS, DIG of Police, addressing the gathering.

Why did the Rameswaram IOTA operation wait for such a long time, despite all the basic necessities being readily available? It is difficult to answer. The members of the Ramanathapuram Amateur Wireless Association were contacted earlier at the Hamfest at Chennai in 2002. OM Durai, VU2NDR, was the contact person along with OM Satya, VU2LR, and they did try to see something coming up with Dr Selvam, S79BBC and facilities available with him. As it was not an island, as recognized by the IOTA HQ, the discussions had dropped off. They picked up momentum when OM Vittalji, VU2VIT and OM Rama Raju, VU2RMJ came on the scene and started grouping the amateurs with this interest and set a target date for the Island Expedition. We had regular chats on 7070 kHz in the mornings and arrived at the dates of 23 to 31 August 2004. No invitations were sent to anyone to join the group, nor was any interested person denied entry to the group.

With that broad outlook, a group of 13 operators joined together to make the pioneer team. The applications from everyone in the group for special call sign AT0RI, for the period 23 to 31 August 2004, with a temporary change of location were requested. The Wireless Planning and Coordination wing of the Ministry of Telecommunications was very kind to grant permission. VU2FBI, VU3RRU, VU2GUR, VU2UR, VU2VIT, VU2NDR, VU2JVA, VU3YFD, VU2LR, VU2RMJ, VU2KLG, VU3WAI and VU2KGN formed the officially permitted group for this island expedition.

Some History
A brief historical detailing of the Amateur Radio activities in the coastal islands of India is not out of place. The states of West Bengal, Orissa, Andhra Pradesh, Tamil Nadu, Kerala, Karnataka, Goa, Maharashtra and Gujarat have territorial waters with some islands. IOTA HQ listed all the islands into their respective Indian state groups in their Directory, which formed the reference data for anyone to use to plan a DXpedition.

The earliest Indian coastal island operation was the one organized by OM Bernard, VU2BMS/DL2GAC/H44MS with hams from Bangalore and Mangalore to St Mary Island of the Karnataka State Group. This operation got the number AS-096 for its activity.

In the late '90s, OM Arasu, VU2UR was very enthusiastic about the IOTA program and had applied for the Participation certificate of IOTA-Millennium Award of 2000. SWL Vis, VU-0020 and VU2UR applied for the basic IOTA-100 award. After receiving the award, interest was further ignited. In the month of January every year (between the 10th and 17th), the Calcutta VHF Amateur Radio Society, at the request by the State Authorities, was attending to the traffic problems on Sagar Island, when hundreds of people go there for the Sagar Mela for a holy dip in the confluence of Ganges River with the Bay of Bengal. On one such occasion, OM Horey, VU2HFR and others were contacted by VU2UR and told about the IOTA program and Sagar Island being a listed unnumbered island of the West Bengal State group. The group took it seriously and worked HF, along with VHF, and provided all documentation to IOTA HQ in a very short time, and achieved the number AS-153.

The Mangalore Amateur Radio Society, with OM Sri, VU2SBJ, in the lead, took up a second expedition to the St Mary Island. Then, they tried a bigger adventure in planning and executing their next island expedition to Sacrifice Rocks of the Kerala State Group. This was indeed the toughest of the coastal island expeditions in India so far, and the group did a fantastic job and achieved the number AS-161.

Then followed the saga of another adventurer by name OM Basappa Arabole, VU2NXM. He jumped in to activate some island in the Maharashtra State group and selected Janjira Island. He got the permission of the Ministry and just before departure, came to know from IOTA HQ that this island cannot be accepted as it is an island in an enclosed bay. With that reply also in mind, OM Basappa did go to the island and operate from there but, unfortunately, he made only a few QSOs and returned. By that time, IOTA HQ had revised its listing of islands of the Maharashtra State group and added Butcher and Elephanta Islands. This boosted morale and OM Basappa planned another attempt, this time to Butcher Island with a special call AT0BI from the Ministry. The Mumbai Port Trust Authorities refused landing permission, advising that it is a "restricted" area and Amateur Radio activity can as well be carried out at Elephanta Island. Immediately, a request to the Ministry for a change of location to Elephanta Island with the same special call, AT0BI, be granted, was faxed. It was, again, the most understanding Officers of the Ministry who rescued us by granting permission. Thus, the first phase of Elephanta Island was carried out and the number AS-169 for the Maharashtra State group was obtained. OM Basappa, VU2NXM, with his small dedicated group, did a second phase operation also to Elephanta and had given the island chasers a second chance at a QSO from 23 to 26 July 2004.
Permission is Granted

Coming back to the Pamban Island Expedition, the Tamil Nadu State Authorities granted permission and accommodation in the first floor of the Taluk Office building at Rameswaram for the expedition operation and demonstration of Amateur Radio in times of disasters on 28 August. The collector of Ramanathapuram showed a lot of interest in encouraging all this, and getting the press, radio and television authorities for the demonstration. The foursome, OM Rajan, VU3WIA; OM Prasad, VU3YFD; OM Guru, VU2GUR, and OM Arasu, VU2UR, left Tirupur on 22 August by road and arrived at Rameswaram by 1930 IST the same day. Rameswaram town had a fluctuating voltage between 195 to 235 V, 50 Hz. The weather was humid with humidity hovering from 60% in the daytime to about 90% late at night. The temperature was about 30 degrees C during the day and about 25 degrees at night.

Just after dinner, these four started assembling the basic inverted V antenna and finished the assembly of the antenna and the layout of the equipment by 1830 UTC 22 August. As the permission was effective from 23 August, the team jumped to work the anxious island chasers right after 1830 UTC, and on 7 MHz CW they contacted over 120 DX stations before they hit the sack. After breakfast on 23rd, the assembly of the Cushcraft MA5B, three element, five band antenna (covering 20, 17, 15, 12 and 10 meters) was taken up by the owner, the visually handicapped OM Rajan, VU3WIA. By 0700 UTC, the beam antenna, the G5RV, the Diamond D-130 VHF/UHF antenna and an HB9CV for satellite work, were assembled. From then on, there was, nothing but pileup on every band and mode. Slow-scan TV and PSK31 were also used to give a few island chasers QSOs in these modes. OM Roger, G3KMA was kind enough, amidst his busy working schedule, to come on 14,260 kHz at 1731 UTC 24 August and advise us of the provisional number AS-173 for Pamban Island.

Chaos
While working SSB on the various bands, it was "chaos" from the European stations. A very strict directional CQ call to NA W/VE and JA were given and Europeans had to be "ignored" to work some of these areas. Even while working Europeans, the island chasers were not listening to our instructions and caused unnecessarily heavy QRM to everyone. Then on, we were forced to work Europe, also in random order/prefixes so that all, especially the weaker ones, get a chance. Even then, there were still a few obstinate callers. There were quite a number of "brickbats and bouquets" expressed on the operating frequencies in a number of exchanges. But the operator of AT0RI continued amidst all these and gave QSOs. There were the usual multiple QSOs from some clever operators and we had to tell them to QSY as we have them on our logs.
This was continued on the day of the demonstration, 28 August 2004, also on the first floor of the Taluk Office Building, and the big gathering of schoolchildren, State government officials and the general public had a question-answer session and a number of display items on the walls were eagerly read and understood. The District Collector, Mr Chella Muthu IAS, presided over the program and Mr Alexander, DIG of Police who was also present spoke to the audience. The IOTA operators and the guest operator YL Sarla also spoke in the Tamil language. The program was covered by the press, radio and TV correspondents in the regional language.

The beam along with the other equipment of OM Rajan, VU3WIA, were dismantled on the 29th, as packing them safely and securely was a major concern and Rajan wanted to do it himself, very meticulously. His assistant and driver Amal, did all the heavy lifting, etc. Thereafter, a few of the operators went in for their religious work to be performed at Rameswaram seaside and taking the holy waters from the 24 different wells on the temple premises. All this took considerable time. An advance returning party with OM Rajan, VU3WIA, in the lead, left Rameswaram. The other operators who were interested in local chats and PSK31 QSOs remained until the last minute of the permission was complete. Then on 1 September they fanned out to their respective QTHs from Rameswaram, bringing the Island expedition to a close.
2500 QSOs/85 Countries
The expedition achieved around 2500 QSOs (putting all the modes together) to all the continents (except Antarctica), covering about 85 countries. The QSL route was given in the QRZ.com Web page, and the QSLs were pouring in, well before we printed the cards. The information about those envelopes that were pilfered and there was no return postage left, the details of QSLs sent, etc, are being shown in the same QRZ Web page to help all the island chasers with the latest information. For this Island Expedition also, YL Vani, VU2LYX, gladly printed the QSL cards and served as a QSO verifier and Manager. The system is working well and the DX operators are pleased with the service.

In addition, all the documentation required by IOTA HQ for formalizing the number AS-173 for Pamban Island from provisional status have been completed.

We thank all those lucky enough to have made QSOs with AT0RI, and we sympathize with the hundreds of others who missed out because of the lack of discipline on the bands. All those who forced multiple QSOs with us could have given someone else a chance for a QSO. The expedition station, barefoot and with a wire antenna, if swarmed like this, can get very few QSOs. Fortunately, we were not on batteries, but on ac power. But at Elephanta this QRM caused us an undue battery drain to complete every call sign. We were not a multinational/ multioperator/multitransmitter station with linear amplifiers to put out a punching signal wherever we transmit.

Thanks
The operators are highly indebted to the Collector of Ramanathapuram, the staff of Project House where our eating arrangements were taken care of, and the Ramanathapuram Amateur Wireless Association for all the help and encouragement.

We also thank all the other visiting amateurs from South India who had the first hand view of what a pileup is, and what an island expedition is, etc. We also thank all those VUs from all over India who took an interest in the whole activity, had QSOs with us and had asked about how they can also organize an island expedition from their state. So, gentlemen, please keep your fingers crossed for the other States of India activating some island in their territory. You may potentially look out for the West Coast States of India, where Goa and Gujarat can turn up surprises.

All the very best, good luck, good chasing of Indian Coastal Islands, and 73.
http://www.arrl.org/news/features/2005/07/12/1/?nc=1

Non-Ham QSO in 40M Ham Band

Dear Hams,

Today morning when I was scanning the 40M Ham Radio Band (7.000 MHz - 7.100 Mhz) at 07:30 am IST, I found some non-ham QSO going on at 7.038.5 MHz. There are more than 5-6 transmitting stations. They are not using any callsign for identifying themselves. Only they asking another station by calling city name. They are mainly doing QSO in between BERELI, MORADABAD, VARANASI, RAIBERELY & KANPUR and also some other city name. I can't follow their messages properly, but they are announcing or forecasting some numeric figures. Their language was Hindi.

I monitored that QSO till 8:00 am IST. Primarily they are using that 7.038.5 MHz in USB Mode. But some stations QSYed to LSB on same frequency for their urgent QSP.

All stations are coming at my end 59. But some stations even 59+40dB on my HF TRX display. My antenna is inverted "V" for 20 Meter.

I presumed that these stations from Uttar Pradesh Water Department. Because last year, during these heavy rain / monsoon months I heard some QSOs going on 40M Ham Band, same day-time. That time they were declaring the water lavel of the Ganges of various cities besides the river.

73s to you and happy monitoring.