Wednesday, June 09, 2010

Handiham World for 9 June 2010

Welcome to Handiham World!

Beam antenna rises above flowering crabapple trees

We are definitely in the summer ham radio doldrums. I can tell that we have reached this time of year by some of the comments I hear, usually by word of mouth or by e-mail:

"What is wrong with the bands?"
"When will the bands get better? I don't hear anything on HF."
"I never hear anything on the repeater."
"My radio club doesn't meet during the summer."
"No one is around to help me with my station/antenna projects."
"When I went to check into the net, there was no net control station and no one ran the net."

Does any of this sound familiar? I hear most of this same kind of discussion every year about this time. As summer arrives here in Minnesota, people start thinking seriously about outdoor activities and taking vacation. Of course we have ARRL Field Day in June each year, but the overall disconnect from many ham radio activities really begins in mid-Spring, generally following Dayton HAMVENTION.

Mother Nature contributes to the problem of HF operation by throwing thunderstorms at us all summer long. The resulting radio interference pretty much makes operation on the lower HF frequencies something that would try any operator's patience. Then there is the onset of spring and summer jobs waiting for everyone when the snow finally melts here in central North America. I have noticed that radio club attendance usually starts to decline in March. Many radio clubs don't even meet during the summer because everyone has so much going on that it is difficult to find a quorum for a meeting.

When I hear questions about the HF bands, I know that they are usually coming from newbies who don't have too much experience and have never learned about the seasonal fluctuations in HF and VHF propagation. Old timers know that the 6 m band comes alive in the late spring and early summer, just as the lower HF bands start to get plagued by thunderstorm static. If these newbies haven't learned about seasonal fluctuations, they certainly don't know about or understand solar weather or the sunspot cycle either. Oh, well... I look upon it as a teaching opportunity.

Last week we reminded you to get ready for Field Day. As long as band conditions aren't too good, now is the time to head out to the backyard for an antenna inspection. Those of you listening to the podcast can hear me as I go through my usual checklist to make sure that my antennas are going to keep working all right. An antenna inspection should be done several times each year, or even more often if you have experienced severe weather in your area.

What to look for:

Are the antennas still up in the air?

Don't laugh -- I have heard from people who didn't even know half of their antenna was lying on the ground someplace after one of the supports broke. A visual inspection will include making sure that any wire antennas are still in position and that tree branches are not impinging on the radiating element or feedline. Other types of antennas, like vertical or beam antennas, should be visually inspected just to see that all of the elements are in place. If an antenna is designed to rotate, you should look to see that trees have not grown so close to the antenna that they enter the turning radius. So far, all of this can be done by simply walking outside and looking around. If you are blind or have low vision, you will want to get a helper to do this part of the job with your direction.

What about the feedline?

Next, you are going to pay particular attention to the feedline or feedlines, and if the antenna is really high in the air, a pair of binoculars can bring the feed point (center insulator) into focus so that you can see if everything is connected properly. This antenna inspection is a pretty simple one and it does not include any tower climbing. You can follow the feedline down to the point where you can do a close inspection, being sure to include where the feedline enters the building. Since you can actually feel and manipulate the feedline at that point, you can check for any deterioration that might indicate a need for replacement. You will also want to check to make sure that where the line enters through the wall that water or insects cannot get into the building. If coax connectors are covered with a sealant, check to make sure that they are still being protected from the elements. I hope you have some kind of lightning arrestor and grounding system where the feedline enters the house. Check to make sure the connections are solid. If you do any actual work on the antenna or feedline, all of the radios inside should be disconnected from the AC mains to avoid any possibility of electric shock. Remember, at this point we are just doing a visual inspection.

Have animals damaged the coax?

Since one of my antennas is a ground mounted Butternut vertical, I will need to do a close up inspection of the feed point to make sure that the coaxial cable is connected at the base, both the center conductor to the vertical radiating element and the coax braid to the grounding system and radial field. Since this particular antenna model has several capacitors that I can reach from the ground, I can also check to make sure that they have not come loose or broken over the winter. My antenna has a small fence around it to protect the base, and even the fence deserves a quick look over to make sure that it is still structurally sound. The vertical is fed underground, so I will need to inspect the parts that are visible in the feedline system, looking for signs of deterioration or damage caused by rodents or rabbits. (I once looked out the back window and saw a squirrel happily eating away at a plastic lawn chair. Animals can cause similar damage to coaxial cable.)

Towers need special attention.

If you are lucky enough to have a tower, you should also include it in your periodic inspection to make sure that it is structurally sound, and that includes a close-up inspection of at least some of the hardware that holds the tower together and the tower base to make sure that corrosion has not compromised its integrity. Naturally you want to inspect as much of the feedline as you can easily reach around the base of the tower and take a look at the grounding system as well.

A checklist can help. Pilots use them before takeoff - you can use checklists, too.

Every antenna installation is different, so I can't get overly specific about a check list. However, I can say that it is my responsibility to know and understand the design and layout of my own antenna system so that I can make sure that it remains safe and effective. You have that same responsibility for your station, whether you have a disability or not. Perhaps you cannot easily get outside or see the antenna system yourself, but you should still have a complete understanding of where things are and how they work and how they should be inspected so that you can direct your helper or helpers during a routine inspection. Of course it helps to have amateur radio operators -- hopefully friends from your local radio club -- to help you with your antenna inspections. But if you don't, you may have to call on friends who know very little if anything about amateur radio and antennas. In that case, you really have to be able to take charge of the inspection and give good directions so that the inspection can be done properly and your helpers can be safe as they are following your directions. You may want to make a checklist of basic items so that you don't forget anything.

Yes, summer may be the ham radio doldrums, but it is a lot easier to do an antenna inspection on a nice summer day than it is in the middle of winter. So if you can't hear anything on the bands it might be time to think about an antenna inspection followed by iced tea on the veranda.

For Handiham World, I'm...

Patrick Tice