I’ve been looking around for good ideas for a portable HF antenna and finally settled on Robert Johns’ (W3JIP) plan from a QST article (Aug 88). The antenna design is a vertical dipole (6M to 40M), using a loading coil at the base of the vertical with a tap and the other half the dipole is formed with a 1/2 wave length cut of wire. The coil is mounted on a 3/4″ PVC pipe which slips into a 6″ length of aluminum tubing. The tubing then slides into a bracket designed to hold a flag. Mounted on the bracket is a SO-239 with the center pin making contact with the bracket. The main element sitting on top of the coil is 8′, but you can lengthen it to 11′.
I spent the morning gathering the parts, had a hard time with some of the specific items, but ended up with a couple work-arounds. I put the coil together first, that went pretty easy. W3JIP’s plan calls for #8 aluminum ground wire for the coil – which no one has. I used copper instead. I wrapped the copper around a 4″ piece of PVC. The directions call for 12 turns, but I only purchased 12′ of copper (the directions didn’t say what length to get)… ended up getting 9 turns. I mounted the coil to the PVC and then secured the trailing end up the coil to a piece of aluminum tubing inserted inside the PVC. The element gets mounted above the coil and I secure the tap at the base of the element.
Once I had everything together, I went outside and mounted the coil section to the top of a tripod, inserted the 8′ aluminum element above the coil, set the tap at the top of the coil, ran a length of wire out as the other half of the dipole, ran some RG-58 out from my Icom 706 and after playing with the tap a bit was able to get out to Texas on 20M.
I have some more work to do:
- better secure the SO-239′s center pin to the bracket and bottom of the coil
- attach a banana plug to the ground side of the SO-239 to allow quick changes for switching bands
- find a way to secure the base of the antenna to a painter’s pole
I know the antenna will work on 20M, now I would just like to get it working on 40M.
On Sunday I headed out to Fort Monroe and activated the Old Point Comfort Lighthouse with limited success. About 4 hours on the air and two contacts. The first contact was Colorado, a loud, booming 59. The next was Virginia Beach…. about 5 miles across the water. I need to come up with a better plan than my hamstick vertical. I’d like to do the next activation during Amateur Radio Military Appreciation Day coming up on Memorial Day weekend.
Anyone have any antenna ideas?
Just added some more memory to the Linux tower (aka garage box)… dropped in an additional 512MB SDRAM SIMM and after a reboot it is now operating much quicker. Also made an adjustment to the xorg.conf to fix the video card. It’s an old VooDoo 3Dfx card and although recognized, it defaulted to a screen resolution of 800×600 without allowing any changes. Now it’s defaults to 1200×1048… much better.
Now it’s back to weeding through the old harddrives.
I was able to get the tower up and the wireless card working. I’m also able to access the box via ssh sessions. Learning alot and having fun.
I pulled out all my junkbox computer parts, gathered the two desktop towers that had gone south some time back, and hauled it all in to the family room along with a huge monitor. The mission – setup a desktop tower running Ubuntu Linux in the garage and attach it to the network with a wireless connection. I want a desktop that I can use for data storage… music, video, pictures. I’ve got a lot of old harddrives, including USB drives, that I have no idea what’s on them.
Out of the parts box and between the two desktop towers I was able to come up with one working motherboad (Tyan S1854), a Pentium III 450MHz CPU, and 64MB of PC100 RAM (2x DIMMs, 32MB each). Not too impressive. But it worked. I installed Ubuntu to a 18GB harddrive, using a bootable CD for the install. 64MB is slow going.
The task now is to get the Linksys wireless NIC card up an operational.
I got all the various multimedia files to play nice with my Ubuntu installation. To include streaming media… I really enjoy listening to NPR using streaming audio and I’m glad I got that working. I’m reading a new book called Beginning Ubuntu Linux, which is helping quite a bit. I think the next stage is to revive one (or more) of my dead desktops and setup a file server out in the garage.
World Amateur Radio Day, Tuesday, April 18, commemorates the founding of the International Amateur Radio Union (IARU) in Paris in 1925. The 2006 theme is “Amateur Radio: A gateway to information and communications technologies (ICT) for today’s youth.” With support from PZK, the Polish Amateur Radio Union, MK QTC, the Polish radio amateurs’ journal again will sponsor the World Amateur Radio Day (WARD) certificate. To qualify, stations must complete 10 HF contacts or 5 VHF contacts on April 18 between 0000 and 2400 UTC. To obtain the full-color certificate, send a log extract including the list of QSOs and $6 US (€5) to: The Radio Amateurs’ Journal MK QTC, Suchacz-Zamek – Wielmozy 5b, 82-340 Tolkmicko, Poland, on or before May 31, 2006. The World Amateur Radio Day certificate also is available to SWLs who log the same numbers of reports.
Click on a digital mode to hear a brief (most <100 kilobytes) sample of the sound these modes make. Hopefully this link will help you identify a mode you’ve heard (or help me identify ones I’ve heard!). Many folks have submitted excellent quality, lengthy files which are no trouble for me to accept, but I do generally drop the sampling rate and length to make them more reasonable to download over a dial-up line. The intent here is more for recognition by ear than for signal analysis. I have higher quality samples of some files, please email me to request them (up to 3MB).
My latest dabblings in Linux prompted me to dig out my copy of Neal Stephenson’s “In the Beginning… was the Command Line” – it’s a wonderful read:
“So when I got home I began messing around with Linux, which is one of many, many different concrete implementations of the abstract, Platonic ideal called Unix. I was not looking forward to changing over to a new OS, because my credit cards were still smoking from all the money I’d spent on Mac hardware over the years. But Linux’s great virtue was, and is, that it would run on exactly the same sort of hardware as the Microsoft OSes–which is to say, the cheapest hardware in existence. As if to demonstrate why this was a great idea, I was, within a week or two of returning home, able to get my hand on a then-decent computer (a 33-MHz 486 box) for free, because I knew a guy who worked in an office where they were simply being thrown away. Once I got it home, I yanked the hood off, stuck my hands in, and began switching cards around. If something didn’t work, I went to a used-computer outlet and pawed through a bin full of components and bought a new card for a few bucks.”
Today is the Chesapeake Amateur Radio Service’s SpringFest – a hamfest! I should be heading over later today to see the sights. I don’t plan on buying anything, but you never know.