Friday, February 3, 2012

Ongoing New Ham Progress: Antenna Work Today

Since obtaining my amateur radio license 73 days ago, I've made it a point to do something to get my station established every single day. Even on the days when I took a short get-away vacation with my wife, I took a little time each day to look at Craig's List for HF rigs, and on our last evening we went and bought a rig near where we were staying.

Some days it's been hanging dipoles and burying ground rods, other days it's been drawing QSL cards and applying for vanity call signs.

Today was one of the more active days, and it was a good day, too.

Pick and Choose

I've got several different projects going all at once. There's a lot to do. I'm still reorganizing the garage to make room for my planned shack location. I've got a dodgy short term 40m dipole up, a new 2m J Pole thanks to W6WEM, a nearly-done 10m loop, and prep work to do for a planned skywire loop for either 80 or 160m. Plus I'd like to order myself a new 2m rig and a 2m HT for my daughter, KJ6TFT--her birthday is this month.

Antenna Work

For today I decided to go with antennas. Exactly what was the next question. It's tough to pick if you have several possible directions you can go, each with different amounts of money and effort involved. Plus knowing that at the end of the work and money spent you may have ruined what did sorta work and replaced it with something new and expensive that doesn't work at all.

Ah, the joys of technical hobbies!

First I decided I should focus on what I had on hand rather than taking the time to leave the house and buy more parts. Feedlines was what I was thinking of buying today, from a local communications company. I figure I'll even pay them to put the connectors on for me.

But I've been dragging my feet on this. Without knowing where the antennas are going to be when I get them in a place where they work well, it's hard to know how long to make the feedlines. Too short creates an obvious problem--it won't reach from the antenna to the radio. Too long and I'm losing signal to line losses. Just to be clear, I'm not looking at ten or twenty feet too long, but at possibly 50 to 100 feet longer than may turn out to be required.

So...

I wanted to get the jpole up, so I can hopefully check into the local club nets without a broomstick in the driveway My feedlines on hand are a 70' length of RG-8, a 90' length of RG-58, and a 30' length of RG-58. While the RG-58 is fairly low loss foil shield type, a check with the MFJ-259B told me it's still going to lose about 2dB of signal over the length of the longer piece, which I'd need to get the jpole up where I want it, much more than the RG-8.

And the RG-8 was inconveniently located on my 40m dipole.

So I decided my first task would be bringing down the dipole. It's not easy making your first task taking something apart before getting something else working. I had to fight off the temptation to change gears to work on the 10m loop antenna.

I went up planning to drop the mast on my roof that supports one end of my 40m dipole. When I got there I saw that I could make the job easier by cutting the current mast into sections. Then later I could insert an extension to make it taller. In part, the height of the 40m antenna is limited by the RG-8 feedline's length. a feedline that's longer, and lighter, would allow me to raise the antenna. So I climbed down, got a different set of tools, and creatively cut the mast to bring it down without disturbing the original support.

Once down, I disconnected the RG-8 and decided to make some changes to the center of the dipole. Since it's still a temporary antenna, I didn't want to get too carried away, but I felt I could make some quick improvements that would pay off until I get either of the two loops up. I spent about half an hour on that, then returned to working on the jpole.

I fished out the fiberglass pole I'd originally used with my 2m ground plane (which got me nowhere until I put it on a broomstick). I checked to make sure it'd support the jpole well, adapted the jpole to the fiberglass pole so that it'd stay put and not come loose or move freely.

Then I took it up on the roof, and refurbished the fascia mount I'd used before. Fortunately I was able to get it to where it'd support the jpole and its mast safely, then took it down and added the feedline to the mix. The support was still sturdy with the weight and strain of the feedline, fortunately.

In the home stretch, I dithered about whether to add an "ugly balun" in the few extra feet of feedline. I've heard both ways for jpoles. Finally I decided to wind a choke in the feedline near the base of the mast, well below the bottom of the 'j'. So if the feedline's braid is forming part of the radiator, there's about 2.5m of it free to do so. But there's also an inline RF choke to limit RF coming back into the house.

Checking the New Antenna

I went inside and hooked up the MFJ-259B to the RG-8. The antenna looked good. Its SWR was good across the 2m band. Its resonant frequency is a little low for FM phone, it's near the top of the CW-RTTY section of the band. So I may see if I can retune it a bit before it goes to its eventual permanent location (more on that later.)

OK, I have antenna and feedline. Now, the rig! An HT...?

When I bought my HT, I thought to get an antenna adapter for it, too. The HT takes an SMA male connector on its antenna, I got an SMA to BNC adapter since I'd used BNC connectors on several of my 2m antennas in the 90s.

Now I put on the SMA to BNC adapter, then hooked up a BNC to SO-239 adapter. Then screwed the rig into the feedline. Well, a few feet of RG-8 are heavier and harder to move than a little HT, after all.

I tuned around a bit, and heard a conversation on a repeater in Vacaville, a bit over 80 miles away. Woohoo! I tuned to the frequency of W6EK, the repeater for the Sierra Foothills Amateur Radio Club and gave it a try, asking for a signal report. Nothing. No courtesy tone, no repeater waking up and identifying itself. I tried again, with the same result.

Then I moved over to the frequency for the Nevada County ARC repeater, W6DD and had another try. Success! I got back a reply of "5 but scratchy". I could at least keep checking in to that net without standing outside.

The scratchy bit concerned me, though. I was holding both the HT and the feedline because I didn't want to support the HT by the feedline but I also don't want to strain the HT's antenna connector with the stiff, heavy RG-8 cable. After listening for a while, I realized I was getting some dropouts on my end. The BNC connection wasn't as secure as it should be.

I tried another adapter and an old PL-259 to BNC cable with an SO-239 union in the line. It was even worse. So I filed that problem away mentally and went back outside to finish dealing with my HF antenna before the brief winter daylight was gone.

Restoring the "Old" Antenna

Half a dozen trips between roof and garage got the right tools and parts for a mast extension up there. As I worked, I was adding refinements. I decided to add a halyard arrangement to the mast. Before, it took bringing down the mast to get at the antenna. One eyebolt and a bit of rope now let me run it up and down with the mast in place.

The new mast came out about 8 feet taller than the old one. I'd sort of hoped for 12, but I didn't want to push its stability too far yet. I think I know what I need to do to get a 40-50 foot mast stable now using purpose-bought parts rather than whatever's in the shop. And the halyard is sweet. I had to rearrange the end support for the antenna to accommodate the changes, but thanks to the halyard the mast stayed up while I did it. And I erected the mast without the antenna pulling on it.

I also have a plan to raise the other end a bit, if I get back to it. But the antenna is laying much flatter than before. thanks to the higher mast, better adjustability with the halyard, and lighter feedline. I just had time to go inside and get a quick look with the antenna analyzer once it was back up. I had a dinner date with my wife tonight, with plans for a family game night once we returned home.

The antenna analyzer shows the reworked antenna at resonance at 7200kHz, with a 1.0 SWR. The SWR across the band peaks at 1.2. 15 meters looks better, too, and almost as good as 40. I went quickly through the spectrum, and I may be able to work in part of the 20m band with this antenna now, but the other bands didn't look promising. I'll take a better look tomorrow, and see if I can arrange a contact on 40m. I've had a few folks offer to help me out there.


Gaining Experience and Perspective

As I worked today I had an eye toward my future skywire installation. One of the tasks I laid aside today was walking around with a tape measure and a kid to plot the distances of trees on my property. I've been thinking in terms of a 160m loop, but today helped me see that I'm already halfway to an 80m loop. One leg of a square 80m loop is about 62 feet, not too far off from the length of my 40m dipole. Knowing that, I can eyeball the distances to two other possible supports.

So an 80m loop is what it'll be. No sense trying for a "bridge too far" when something good and not too difficult is right at hand. With an 80m loop, I can see not only the generalities of what I'd like to do, but also the details of what I actually can do to get it up and running. I'll probably do a "science experiment" on the upper part of the 40m dipole to make sure I know what I'm doing, but if I am, I could possibly have the loop up that day if I have the parts on hand. And part of the idea gets me a pair of 2m antennas (1 vertical, 1 horizontal) up where they may get a signal out to the south of me.

But more about that at a later date.

When my wife and I went to dinner we made a brief stop at W6WEM's house to take the pictures of his loop that I couldn't get on my first visit. It gave her a chance to see firsthand what sort of thing I'm planning to erect at our house. I think she was pleased by how subtle it was. I had to point it out to her, and she remarked "Oh, that's not bad at all!" with a pleased tone to her voice. I expect she'd already steeled herself to some sort of wire basket monstrosity weaving from tree to tree with dead condors caught in its arcing sections and lots of spiky bits to catch lightning and direct it at our house.

After dinner we made a brief stop at Radio Shack, where I may have found the solution to my bad 2m connection between tiny handheld and heavy hose feedline. Tomorrow will tell.

This is why I put so much effort into temporary stuff. The temporary stuff teaches me what I need to know to make good permanent stuff. And to have a realistic perspective on the resources and effort it'll take to build it, maintain it, and be effective with it. I've heard a lot of stories about stringing up some ad-hoc antenna and working DX the first night. I don't doubt them, but I always suspect there are far more stories about putting in a bunch of effort and getting nothing. Those stories aren't as much fun to tell.

I decided to talk about both my successes and my failures. Keeping astronomy observing logs since I was a kid taught me how much I learn from recording the nights where I go out and don't see a thing. But I learned. Now I hardly think about some of the lessons I've learned. Going out and seeing all, most of, or more than what I planned when observing is the norm now. But I had to learn some things along the way. Often through a bit of reality hitting me in the unrealistic hopes or poorly prepared plans.

I'm still learning a lot in amateur radio. Some of I have yet to learn is implied in what my fellow hams say to me that I've yet to learn to appreciate fully. Some is just incrementally working my way through the stages I'm in now.

I definitely have much more of an appreciation for what it takes to set up a solid station. And I'm also much more confident that I'm going to have something I can manage and keep on the air soon.

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