Last week, Tack JE1CKA and his girlfriend came to Guam for vacation. Tack is a well known contester in Japan and around the world. Unfortunately, the weather did not cooperate for him, but fortunately he was able to stop by for a short visit.
I’ve met Tack twice before. Once many years ago in Saipan during one of the KH0AM multi-op efforts, and again in 2006 in Brazil for WRTC. He and KG6DX are the only two hams who’ve visited my station to date.
I have been very busy with my job as a Coast Guard Port Engineer and Contracting Officer’s Representative. The Coast Guard Cutter WASHINGTON has been docked since June for about 2.5 million dollars of maintenance work, including about 600 square feet of plate renewal. This project has kept me busy, and off the air for much of the time.
Today, we launched the ship at first light. I am looking forward to completing this project in the next week or two, which should free me up to chase DX and pileups on the low bands (and high bands if the conditions hold up).
After a week of bad weather, we had two nice days over the weekend with low humidity. Perfect to go out and repair my African Beverage.
All my Beverage receive antennas are located in the jungle, on government property just on the other side of the fence from my housing area. Getting to them isn’t very easy – I have to ride my bike, carrying everything I need, about 1.5 miles to get to the feed points. I can’t climb the fence (topped with barbed wire), so I have to go out the front gate and ride around the fence line. It is a small sacrifice to make to have great ears on the low bands.
Because of the distance, I have to check and double check that I didn’t forget anything.
Today, I packed pliers, torch, solder, wire cutters, hammer, nails, homemade insulators, electrical tape, and 700 feet of #18 copper clad steel wire. This is along with the items I always need: long sleeve coveralls, gloves, sweat rags, bottled water, sneakers, branch cutters (for cutting vines), machete, and bug spray. This all gets shoved into a backpack. I need the sneakers since my bikes all have clipless (not platform) pedals that require special shoes.
Once in the jungle, I have to change my shoes, put on the coveralls (long sleeve to protect me from sharp leaves and bugs, and douse myself with bug spray because the mosquitoes are really bad.
When I originally put up my African Beverage, I didn’t have any of the copper clad steel wire I normally use, which has held up with no problems. Instead, I used what I had: #18 stranded copper wire with white insulation. The problem is that the wire sagged, and where it did, the pigs chewed it up. The black insulated RG6 coax gets ignored, but the white wire gets chewed to pieces. I suspect it looks a lot like the pig’s primary food source: grubs.
I also had to replace some of the insulators, since the trees have grown in the six months I’ve had the antenna up. Stuff grows really fast here!
Now, I have four working Beverages again. I’m ready to try to work the last zones I need on 160m – almost all are in Africa. It is not a difficult path, however European and Japanese pileups make QSOs with this region very difficult.
Over the last two weeks, I was able to complete my phased 40m vertical project. My original plan was to use the standard, 90 degree spacing, fed 90 degrees out of phase. I discovered the day after setting the 2nd vertical base that the house next to mine would be occupied. Since this 2nd vertical would be quite close to the house, I decided to rethink the array, going with 1/8 wave spacing fed 135 degrees out of phase. Gain figures are similar, however the lower feed point impedances you get with close spaced verticals means ground losses are amplified. 2 ohms of ground loss means a lot more when your feed point impedance is 15 ohms vice the standard 36 ohms, when efficiency is taken into consideration.
In my case, I placed the verticals in a N/S configuration. The beamwidth is wide enough to cover both Europe and North America. They are fed using standard published figures for the Christman Method of phasing – 157 degree delay lines to each vertical with a 39 degree delay line to create the phase shift. In my case, the actual numbers needed may differ, however I don’t have an accurate enough method of measuring complex impedances so I went with the standard values.
Under each vertical are at least 40 radials (the older vertical has more). The white PVC sleeves the lower section of both verticals for safety reasons. My new neigbor has a toddler who likes to run around the back yard, including mine. The PVC increases visibility and should allow him to bounce right off the antenna uninjured should he run into it.
The below photo shows the switching relays. I built them into a Home Depot outlet box. There are no Radio Shacks here – and I don’t want to wait two weeks for a Mouser order to arrive. I’ve found that it is nearly impossible to keep water out of an enclosure, so I don’t worry about it. The stamped box works fine for shielding, and a bucket over the whole thing keeps the box and coax connectors out of the rain. The center relay is used to switch between the North and South positions, and the relay to the right in the photo shorts out the delay line for omnidirectional (theoretical 0.3db gain to the East and West).
How does it work? I won’t really know until the Oceania DX contest. Over the past year, I had a single vertical and a dipole. At no times was any antenna better than the other. I have to assume the 2nd vertical gives me something – even if less than nominal gain – unless I have serious ground loss issues which I don’t think I have. There is some interaction with the Spiderbeam mast. I see big F/B (24dB) on 4W6A who is almost South of me, but little change on stations to the North. My QSL manager, W2YC, seems to think I’m about 1/2 S-unit louder in the north position which does back the theoretical 3dB gain figure.
Last night, 4W6A showed up on 80m. Piece of cake I thought. Switch to the 80m antenna – to find a high SWR. I eventually work them anyway, with a struggle (4W is a chip shot from here).
This morning, I go to troubleshoot the problem. I figure the same thing happened as always – the vertical wire contacted a wet branch, and arced. I pull the antenna down, but after an hour, I can find nothing wrong.
I keep looking for 20 more minutes, checking continuity with my meter, ETC – it must be a broken wire hidden in the insulation – could it?
Before I renew the whole section of wire, I look at the feed point.
You can clearly see that the 80m side of the ladder line broke.
I learned early on that I need to maintain heat control when soldering the copper clad steel. Too much heat, you burn away the copper, leaving steel that will rust and break. The feedpoint connection was made because I realized this.
5 minute fix, and I’m back on 80m with a working antenna.
Yesterday was an overcast and rainy day, perfect for antenna work since it wasn’t that hot.
I was able to complete one of the items on my list of improvements, which was to remove the 40/30m dipole and to raise the Spiderbeam a few feet higher. I was also able to renew the coax feed to the beam. I had been using a length of LMR400 that was given to me by K1PT a couple years ago – after it had been on his tower for several years.
For my antenna mast, I use something readily accessible on Guam – Schedule 40 galvanized pipe. I have a weight allowance every time I transfer, and exceeding the limit would cost me many thousands of dollars. My wife and kids are very thankful that I allow them to pack their clothes instead of tower sections – so I improvise.
Water pipe telescopes nicely, except for 1.25″ to 1.5″. There is an interference fit of a few thousandths. As a result, I telescoped 1″ into 1.5″ into 2″ pipe. This got me 28ft to the rotator, plus a few feet of aluminum mast and the Spiderbeam is at 35ft.
To keep the much smaller 1″ pipe from fitting sloppily in the 1.5 inch size, I cut and slotted two rings of 1.25″ pipe, which I then pressed over the 1″ pipe at the bottom and 2ft from the bottom. With some grinding, I was able to make a nice fit to remove the slop. Unfortunately I don’t have a photo to share because it was raining when I had everything taken apart.
To extend the antenna higher, I bought a 10ft length of 1.5″ pipe for the bottom section. Being conservative, I pushed the 2″ pipe up 6ft, pushing the Spiderbeam up to just over 40ft high. I also renewed the guy ropes – guying is a must. I like to use parachute chord, which is inexpensive, rated to 550lb breaking strength, and handles the sunlight (UV) well. I’ve had the mast up for over a year at the old height, and I had no sign of problem in 30MPH winds. This is usually the maximum we see here unless a tropical system is nearby, and in those cases the antenna and mast would be taken down for safe keeping.
I drilled small holes every 12″ in the smaller pipe sections and every 6″ in the large 2″ pipe. This allows me to slip a small 1/4″ bolt into the hole, so I can rest, relocate the pipe wrench, and lift again. This way, I can raise and lower the antenna myself in about 10-15 minutes. Once a pipe section is pulled all the way up, I use a large through-bolt to lock it in place. Like climbing a tower – I always use two bolts so one is always in place at any time, so it won’t come crashing all the way down if the wrench slips.
In the above image, you can also see the rats nest of para cord and ratchet straps I use to fix the bottom piece of pipe in place. No holes are allowed to be drilled into the house – when I move there will be no evidence of the antenna aside from the concrete base which is mostly buried.
I feel much better now having taken down the mast extension and the 40/30m dipole. KL9A teased me, saying I gained a full 0.1dB of improvement by raising the antenna 6ft. I would like to think I gained more. Perhaps going from 120 to 125ft is not much of a difference, but 35 to 40ft should help, especially on 20m. I did notice an increased noise floor – probably related to the new coax run – I will have to confirm once I repair my MFJ-259B and test the old LMR-400 for loss.
I’m thinking that I may not put the dipole back up at all. I’ll have to experiment and see. I have a new neighbor moving in next week (which was unexpected), and like the uncluttered look. I don’t want to press my luck with the housing manager. The vertical was equal to the dipole into Europe and North America, so I don’t think I’m losing anything if I don’t put it back up.