Sunday, July 27, 2008

My first beam - Part 3

If you haven't already seen them, you might want to read Part 1 and Part 2 of this series first.

Now that I'd gotten the beam, including the puzzling-to-connect-the-right-way mast plate assembled, it was time to take it outside to check the SWR and to make a couple of test contacts. As I mentioned in Part 1, I assembled the antenna indoors because it was extremely hot an humid out. There was plenty of room on the flood of our "great room", and the sliding door that went outside seemed like an idea way to get the beam outside once finished. Unfortunately, I failed to measure the height of the door before making the assumption about using it to take the beam outside. It turns out that the door opening is 6' 7" high (2.01m) while the beam (for those of you who weren't paying attention) is 6' 9" (2.06m) long. Oops. I remember that when the room was being built, with the door in place, they had to remove both sides of the sliding door in order to get the big-screen TV inside. While comtemplating doing that, or thinking about removing the elements temporarily, Sharon suggested that if I twisted the beam through the door that it might fit. Fortunately, she was right, and the screwdrivers and wrenches remained safely in the toolbox.

Now that the beam was outside, I wanted to put it up in the air and check the SWR with my antenna analyzer. I have three five foot (1.54m) sections of TV mast from Radio Shack that I've used over the years, plus a stake that is made to fit into the bottom mast section. The idea is that you pound the stake into the ground, put a plate (that came with the stake) over the stake, then the mast onto the stake, resting on the plate. It's definitely not for permanent use, but for a lightweight antenna for temporary use when there's no wind, it works fine. If I needed to leave it up a little longer, I have a collar that fits onto the mast with holes for ropes to uses as guys, but for what I was going to do, the stake was just fine. Unfortunately, I've now used the stake enough to that the top part (which you hit with a small sledge) has flared out, making it impossible to fit the plate over (which isn't a big deal), but also making it more difficult for the mast to slide on. (By the way, the stake that I got was the last one in a closeout bin at Radio Shack a couple of years ago. If anyone knows of another source for these, please let me know, I'd like to pick up another one or two.)

I did manage to get the stake into the ground and put the bottom section on the mast on it. I then started to attach the beam to the mast, figuring that I'd walk up the mast and lift it on top of the section already in the ground. The beam itself only weighs 6 pounds (2.7kg), and even though the mast sections probably weigh more than that, I figured that I could lift it myself. That wasn't the problem, but what I'd forgotten was that with the mast attached, I still had to attach and temporarily secure the feedline, but could no longer lay the whole combination on the ground. I used a trick I learned at Field Day which is to rest the mast on a ladder, which keeps the antenna off the ground and allows you to work on attaching the feedline. Fortunately, since the beam was small and the mast was short, I was able to use a pretty small stepladder that we had in the garage, attached the feedling to the feedpoint and secured the cable to the boom and mast with a few tie-wraps.

Walking the mast and antenna up to vertical position wasn't difficult to do by myself, though it certainly would have been easier had I had a helper. (I certainly will have help when I get this up onto the roof.) Of course, what I failed to realize was that the 15 foot height put the beam right into some low-hanging branches from a tree, so I took everything down, moved a bit away from the tree, and repeated the exercise. Now the beam was free to rotate and clear of the leaves. Before connecting the radio, I used my antenna analyzer to check the SWR and impedance. While I'd hoped that I got everything put together well, I expected to have to adjust the shorting bars or some other component. I was very pleasantly surprised to discover that the SWR at 50.1Mhz was 1.0:1, and the impedance was 51 ohms. (By way of explanation, "perfect" would be 1.0:1 and 50 ohms; I suspect that the error inherent in the analyzer is more than one ohm, so this was, for all practical purposes a perfect match.)

The next trick was to connect the feedline to my radio which involved putting a couple of sections of coax together and feeding them through the back door and into my shack. This worked just fine, but wasn't exactly ideal considering the outside temperature. Since the 756 Pro II has two different antenna inputs, it enabled me to perform a comparison with the 6m loop on the roof. For reference, that loop is at about 30 or 35 feet (around 10m) so it's at least twice as high as the beam on the ground. Although the 6m contest was still on, there wasn't a lot of activity, but using the loop, I did hear a few stations from New England, so I aimed the beam roughly in that direction. Sure enough, the stations were noticeably stronger as compared to the loop. I also noticed that many of the "birdies" (constant signals in fixed locations) were gone. I later realized that this was because at the time the beam was pointing roughly north-northeast, which was directly away from the house. When I pointed in the other direction, the birdies came back, which means that the cause of the birdies is most likely something inside my house. (On my "one of these days" list is to run the radio from a battery and to start shutting off circuit breakers in the house until the birdies go away, which should help me to figure out the source of the problem.)

Since it was getting late, I'd only made a couple of quick contacts, so I took the beam down and found a place in the garage to place it. I still need to order a rotor, then K2NUD has offered to stop by and help get the beam up on the rooftop mast. For now, I'll normally use the loop, but if I have time, I'll try to set up the beam temporarily.

Thursday, July 24, 2008

My first beam - Part 2

In case you missed it, click here to read Part 1.

Now that I had all the parts laid out, I re-re-re-re-read the instructions. First things first: I took out the tools that I needed (listed at the beginning of the instructions) which consisted of a couple of difference sized wrenches, one socket wrench, a screwdriver (oops, grabbed a flat blade instead of the Phillips head; I had a 50-50 chance and guessed wrong), and a tape measure. Amazingly, I actually had the right sized wrenches and socket. (Well, not so amazingly, they were common sizes.)

I wanted to be very careful before tightening any of the locknuts, since I didn't want to have to undo any mistakes, which might have affected the "holding power" of the locknuts. I knew I couldn't mess up the first step, which was connecting the two boom sections together. There really only was one way to do it, since the screw holes on both halves only lined up one way.

The next step was to mount the reflector element on the back of the beam. By way of explanation, the 6m3 antenna is a three element Yagi antenna, a very common type of directional antenna. The link gives a more in-depth explanation, but in a three element yagi there is an element in the middle which is actually connected to the transmitter called a driver, a slightly longer element located electrically "behind" the driver called a reflector, and a slightly smaller element in front called a director. It's important to get these in these set up in the right order or else the antenna just won't work right.

The instructions say "Mount the longest element ... to the hole at the rear end of the boom...". Ok, so, um, which is the "rear" end? The diagram does show spacing between the elements, but I took a quick look at the diagram, figured that the drawing showed the rear of the beam at the bottom of the page "pointing" upward. Of course, had I actually looked a little more carefully I would have noticed that the longest element was at the top of the page, not the bottom. So, I promptly proceeded to put the reflector element on the wrong end of the boom. Fortunately, I intentionally didn't tighten it up all the way, and when I figured out what I'd done wrong, I was able to move it pretty easily. By that point, I'd put on the driver element, which didn't need to be moved, so I only had to move the one element. No harm done.

The rest of the assembly went pretty smoothly. I put on the other components, and attached the balun to the T-match as instructed. In this case, the balun is in the form of a quarter-wavelength of coaxial cable that you're supposed to loop and attach to some connectors then secure it to the boom with the supplied black tie-wraps. (Black tie-wraps are UV-resistant,so they don't break down in sunlight as quickly as regular tie-wraps.) The only problem is that when I did the initial unpacking on the antenna, I must have unpacked the tie-wraps (I'm pretty sure I saw them) and put them down somewhere. Unfortunately, that "somewhere" must be the same place as where missing socks go when put in the laundry; that is, in "never-to-be-seen-again" land. Amazingly enough, I actually had the exactly type of tie-wraps called for in my toolbox, so I used my own. Another bullet dodged. (Ok, another trip to the hardware store avoided.)

Now that I'd gotten all the parts attached and carefully checked the that the shorting bars (used to tune the antenna among other things) were where they are supposed to be, I re-read the instructions to make sure that I hadn't missed anything. The only thing remaining was to attach the boom plate to the boom The boom plate is used to attach the antenna to the mast. There are a couple of U-bolts plus nuts and lockwashers that you first attach to the boom, along with what's basically an adapter to allow you to connect the flat mast plate to the round boom. I will admit that it was a little confusing. There are a lot of holes on the plate, and it's almost like a puzzle: The smaller U-Bolts, used for attaching the plate to the antenna boom, and the larger U-bolts, used for attaching the mast plate to the mast, will fit into the plate in several different ways, but there's only one way that everything will fit in correctly. I have to admit that I probably tried pretty much every possible combination (unsuccessfully, of course) before figuring out the magic combination. One assembled, the solution is obvious, needless to say.

To be continued...

Sunday, July 20, 2008

My first beam - Part 1

It finally happened. I finally have an antenna that can be pointed (where pointing actually has an effect on the radiation pattern.)

Until now, all the antennas that I've had have been (more-or-less) omnidirectional, which means that they work equally well (or equally badly, depending on your point of view) in all directions. After several years of begging discussions with Sharon, she's agreed that it'd be OK if I put a small beam up on the roof. I felt that even a relatively small HF beam was a bit bigger than what I wanted to start with, so I figured that I'd go with a small 6 meter beam. I chose the M2 6M3 (a 3 element beam) based on the specifications compared with similar beams and on recommendations from friends. I really would have liked the 6M5X, a 5 element beam which has better gain, but the 18 foot (5.5 meter) boom seemed a bit much for what I wanted to do. (The boom on the 6M3 is 6.75 feet [2.06 meters]).

I did some price shopping, and found that Gigaparts had it listed for about $30 less than I could find it elsewhere, with the caveat that it was out of stock and the discount only applied while it was out of stock. It turns out that the out of stock condition lasted a lot longer than I (or they) expected, so instead of the antenna arriving in June (I ordered it on May 31), it finally showed up on July 11. Sharon and I were out of town taking a mini-vacation then, and with Justin's surgery coming up when I got home I was very busy, both at home and at work, trying to cram a week's worth of things into about three days. As a result, about all I had time to do was to open the box and take a look at the instructions.

The first thing that I noticed in the instructions was that it referred to the "N" connector on the T-Match. (The T-Match is where the antenna connects to the feedline.) "N" connectors are normally used at ultra high frequencies and above (they were originally designed to be used at microwave frequencies) or sometimes at VHF frequencies when it's critical minimize any signal loss. Normally though, antennas of this type use the more common UHF (or SO-239/PL-259) type of connectors. All of my feedline terminates in PL-259 connectors, so I needed to either obtain a male "N" connector and fabricate a cable, or use an adapter. The adapter route seemed easiest, and fortunately, my friend Matthew, K2NUD, had a spare that he was able to lend me until I could purchase my own.

As it turns out, the instructions were wrong; the connector on the T-match was indeed an SO-239. I didn't discover this until after I finally started building the antenna. So, I'll return the adapter to Matthew, and figure out to do with the other four adapters that I got from ebay when they get here. (Fortunately, they were relatively inexpensive.)

As I mentioned, Justin had his surgery this week on Thursday. I worked Monday through Wednesday trying to cram all my regular weekly activities into three days, and that, along with other "family matters" kept me from looking at the antenna again for the remainder of the week. The really good news is that Justin's surgery appears to have been successful. His back and leg pain have been significantly reduced, and while he's got a fair amount of physical therapy ahead of him, all of us are happy with the results so far.

We brough Justin home from the hospital on Saturday afternoon, and got him settled with his laptop (of course) in front of the TV. After spending a while catching up on some of my emails, I decided that I'd take a crack at putting the antenna together and making making a few QSOs. As it happened, this weekend was the CQ WW VHF Contest, but because I knew I'd be tied up with Justin, I figured that I wouldn't really participate at all anyway, so putting the antenna together seemed like a good idea. If it had been a nice comfortable summer day, I would have gone outside and used the backyard table as a workbench. Unfortunately, it wasn't exactly comfortable. It was about 95+ degrees F (about 35 C) and humid outside. It seemed to me that indoor assembly made a whole lot more sense.

The first problem was finding enough space in the house, and making sure that once I got the antenna assembled, that I'd be able to get it out of the house. The assembled antenna is about 6.75 feet (2m) long and over 9.5 feet (almost 3m) wide with the elements attached. Fortunately, a few years ago we put an addition on the house which we call the "great room" that had a good amount of space, and a sliding door directly to the outside. The first order of business was to roll the area rug up since when I handled the aluminum tubing I realized that my hands were covered with what looked like aluminum powder, presumably from the manufacturing process. Getting that on the area rug would have been A Bad Thing.

The smaller parts (the various nuts, bolts, and washers) all come in sealed plastic bags, and I've had enough experience putting things like furniture from Ikea and kids toys together to know that I need a place to keep the parts after I've opened the bag. Without that, there's some law of physics that comes into play that says something like "any unsecured small part will roll to the most unreachable location possible, assuming that it is not possible for the part to be lost entirely". A set of Tupperware bowls served double duty to not only keep the parts handy, but to the antenna off the floor. I got all the parts together, re-read the instructions, and got started.

To be continued ...

Sunday, July 13, 2008

And sometimes you do get lucky

In my last post, I said:
Unfortunately, unless a miracle happens at some point over the next few hours, I won't be able to work CY0X on Sable Island.
Perhaps calling it a miracle is a bit much, but I did get very lucky. Every couple of weeks, I have a conference call that starts at 7AM local time. One of the not-so-fun things about working for a global organization is that sometimes calls need to be at a "compromise" time so that folks from various parts of the world can get on. Sounds kind of like ham radio, doesn't it? Some DX paths are only open very early or very late (depending on where you're located) and sometimes you need to stay up late, and sometimes you need to get up early. As I believe that I've said in the past, I am not a "morning person". I will happily stay up into the early morning hours, but I really don't like getting up early in the morning. 

However, as they say, "ya gotta do what you gotta do", so on the morning of July 9th I dialed into the conference call from a speakerphone in my office at home and put the call on mute, as much of the conversation was between the other participants and didn't involve me. From reading CY0X's website, I found that they'd been forced to extend their stay due to fog that was keeping them from leaving the island. I tuned to 50.108 MHz, which is the frequency where they've been operating on 6 meters, heard nothing, and turned the volume back down. (Remember, I was on a conference call.) I then figured that I'd bring up ON4KST's 6m chat site

I'm going to digress for a second to give a plug for Alain's site: If you're interested in making contacts on 6 meters, you'll want to have this chat running when you're near your radio (and even when you aren't.) A lot of the "big gun" 6m folks hang out there, and just eavesdropping on their conversations can be extremely educational. Not only that, but, being hams, they tend to be fairly friendly and love to share their expertise. (Of course, as with many topics, if you ask a question you may well get back 10 or 20 different answers, but you will get an answer.) I can't say that I know many of the regulars there well at all, but I've had a few conversations and they've been really helpful. In addition to the chat room, there are windows for 6m packet spots, a dynamically updating customizable map that shows the paths between the spots, and other information about propagation. All the windows are customizable; you can see an example of what can be done at this link (opens in a new window). By the way, for those of you in North America (more specifically IARU Region II) or those of you interested in making contacts in that radio (if you're from outside Region II) make sure that you select "Enter into the 50 MHz IARU Region 2 chat here". Alain has done a terrific job, I can't recommend this site highly enough.

Back to the topic at hand. As I was listening to my conference call, I was reading the chatter in the chat room, and it seemed that there was a very good 6m opening to a large part of the US. In particular, the chat room folks were talking about the fact that CY0X was coming in all along the east coast very well, not only amongst themselves, but also with the crew at CY0X, who apparently have pretty good Internet connectivity out there on Sable Island. Right about then, my friend Larry, N4VA, sent me an instant message telling me that he was hearing CY0X with a very strong signal and that should try to listen for them. With the speakerphone still on mute, I turned up the volume on the radio, and sure enough, there was CY0X, CQing on CW and "lonely". (Which is, I suppose, a euphemism for "they are calling buy nobody is answering them.) I fired back my call a couple of times in answer to their CQ, and initially they I just heard them kept CQing, then I thought I heard a partial reply to someone (couldn't tell if they were responding to me), and then nothing at all. That's the nature of 6 meters, the "magic band". I figured that I'd blown my one and only chance to work CY0X, since I figured that the one brief opening was going to be it. Fortunately, I was wrong. 

Don't forget, I was still on the conference call, and in fact, right about then, I had to provide some information to the group myself. (As an aside, it's too bad there's not an aware for "telephone DX", as today we had folks from the US, the UK, Vietnam, China, Singapore, Mexico, Spain, and I think two or three others that I can't remember now.) As I was talking I glanced at the 6m chat page and saw that one of the CY0X operators, Dick, K5AND, was chatting with some of the folks in the room. I finished my bit on the call and sent a note to Dick saying that I could hear them OK but apparently they weren't hearing me. As a reminder, I'm running 100w into a loop, and while in theory things should be somewhat reciprocal, I wasn't sure if they were running a lot of power, etc. Dick answered back that in fact he'd heard me and given me a single report, but since I never heard that I didn't consider it a valid QSO.

The conference call continued and after a while, topics that didn't require my full attention came up, so I glanced over at the bandscope on the radio ... and sure enough, there was a strong signal again right on 50.108MHz, the CY0X frequency. I turned up the volume (good thing I remember to put the conference call back on mute!) and sure enough, there was CY0X again, stronger than the last time. Again, I sent my call, and this time, they came right back to me, clear as a bell, and we completed the QSO. Within about 30 seconds of the contact, I once again had to return my full attention to the conference call, but CY0X continue to remain strong to my location for quite some time. 

One of the really interesting things is that the guys in the chat room were talking about the particular mode of propagation that enabled the contacts all up and down the east coast of the US to take place. From what I understand about "magic band" propagation, most long distance (around 1000km or more ) contacts are made using a form of propagation known as "Sporadic E", or Es. However, the discussion taking place suggested that a more unusual form of propagation known as "tropospheric ducting" (or "tropo ducting") was responsible for the unusual characteristics of the opening. 

Tropo ducting can produce some pretty interesting contacts. Several years ago I was running a 2m net on a local repeater when a station checked in from Virginia Beach, Virginia. That was well beyond the normal range for the repeater (by several hundred miles) yet he had a very clear signal into the repeater and told us he could hear the repeater quite well. I believe that a number of us made direct QSOs with the station (not through the repeater), and a number of folks that I spoke with after that said that because of the conditions at the time and the locations of both stations, it was very likely that tropo ducting was responsible. 

Unfortunately, there's no way to predict tropo ducting or even the more common Es with any kind of precision. Yes, certain times of the year (such as July) are known to have a greatly enhanced probability of Es showing up, but figuring out when there's good Es or trop ducting still means that you not only have to listen to your radio, but also have to occasionally call CQ. As has been said before, if you have 500 people all listening and nobody transmitting, how can you know if the band is open?

Monday, July 07, 2008

Catching up, again

I've gotten a bit behind after my burst with the three-part series about the ARRL June VHF QSO party. Things have been a bit quiet in radioland for me, and in fact, a quick look at my log shows very few contacts at all after the aforementioned contest. The most exciting contact I had was with TO5E in St. Bart's on July 3, which was a new DXCC entity on 6m for me. Unfortunately, unless a miracle happens at some point over the next few hours, I won't be able to work CY0X on Sable Island. St. Bart's is a relatively new DXCC entity, and I'd previously worked them on some other bands so working them on 6m is nice, but folks live there and it's pretty easy to get to and operate from. I was a little disappointed about missing CY0X on 6m, since although it's existed as a DXCC entity for a long time, I've never managed to work it on 6m. This time, I only heard it once, very weakly, when I was at the radio, so I'll have to wait for the next time.

As I'm sure most of you know, last weekend was ARRL Field Day, but for the first time since I became a ham, I didn't participate at all. We were in Florida to celebrate my mother-in-law's upcoming 90th birthday, and while I did consider taking the small radio with me and attempting to make a few contacts, I realized that we weren't going to have much spare time (I did have about 90 minutes free, which I spent getting a little bit of a suntan while lying around the hotel pool) but more importantly, since we were trying to avoid checking our bags (our trip to Florida was Friday to Sunday), I realized that there was just no way that I'd get the radio and even the smallest antenna I have (the Buddistick) into the carry-on bag I was taking. The past two trips that I've gone down I've taking the radio and operated from Lido Key, which is IOTA NA-034, but unfortunately it didn't work out this time. The closest I got to operating was when I happened to drive past what I realized was the Sarasota Emergency Radio Club's Field Day site. I'd looked it up prior to going to Florida, but  never had a chance to stop by. By pure chance, a route back to the hotel from one of the family functions took me right by there. The next morning, there was a blurb about them on TV, and I'm really sorry that I didn't have a little more spare time to at least stop by.

Despite the fact that I've managed to get a five-day weekend out of the Fourth of July holiday (with the holiday falling on a Friday and my company giving me Monday off as well, I took Thursday the third off to give myself even more time), I haven't really gotten much done on the radio. 6m has been open to at least somewhere every day, but I've had enough things to do that I never seemed to have managed to gotten on the radio as much as I'd like.

As a follow-up, about a month ago I posted a poll asking how folks read this blog. I got 25 responses of which 11 were via an RSS feed and the rest were pretty evenly split between those of you who visit here directly, people who get the feed via email (if you'd like to do that, there's a link right on the main page at the blog website where you can sign up), people who read this via another website (I'd be curious to hear from those of you who do that rather than come here directly; either leave a comment or email me directly) and those of you who read it via the N0HR tool bar. Thanks to those of you who participated.

On a personal note, some of you know that my son, Justin (KC2MCS) has been suffering with a rather serious back problem for well over 2 years. After trying everything else, he's scheduled to have spinal fusion surgery in a little over a week. We are, as they say, cautiously optimistic that this will allow him to get back to a normal life.