Archive for the ‘technology’ Tag

…antenna questions…

So, I’m joining a black bear hunt for this fall on Kuiu Island in Alaska. For emergency communications off the island, I am the only General Class licensed ham (so far) and so I picked up an FT-897 off eBay. This should be a great rig in the event we run into any problems.

I have a ton of questions based on the following information:

  • I have not yet ever operated HF.
  • Though I understand many antenna basics, much of it still confuses me.
  • I do not have an antenna tuner.
  • The manual for the 897 states

    “When installing a “balanced” antenna such as a Yagi or dipole,
    remember that the FT-897 is designed for use with an
    (unbalanced) coaxial feedline. Always use a balun or other
    balancing device so as to ensure proper antenna system performance.”

  • My pack weight for the trip is already exceeded with this radio and batteries, I must go absolutely minimum portable with the antenna.
  • Near the end of the trip, if we haven’t used the radio for emergency contacts, I plan to drain the batteries making QSO’s, which I have not yet made on HF.

Question 1: What band/frequency do you recommend for making contacts from the island?

Question 2: What antenna design do you recommend? It needs to be simple and inexpensive (which I think means a wire dipole), but I’m confused about the statement from the manual about the radio designed for an unbalanced coax feedline.

Question 3: Will I need an antenna tuner? Would an antenna tuner be only for multi band operations? Can I get by without one if I only plan to operate on two frequencies (one for QSO’s and one for the Alaska HF emergency frequency)?

Question 4: What recommendations and suggestions do you have for a beginner making his first HF contacts? I’d like to go on the air and not make “newbie-blunders”.

Basically, I’d like to make a trip to the hardware store this weekend and get the materials to build me an antenna. I can experiment with it next week, while I’m still on leave. I’m just not comfortable enough with the information I have to start building one. I’ve read everything from “you will need an antenna tuner if you are using unbalanced feedline such as coax, even with a balun” to “just throw a wire over a tree and make your contacts”. There’s a lot of middle ground between those statements.

So, any ideas for the newbie? Thanks in advance!


…private pilot…

Well, it is official. Today I was issued my FAA Private Pilot license. 31 January 2008. Cool date.

(Side Note of interest) 50 years ago today was the successful launch of America’s first satellite, Explorer 1. See the news article here:

And, back to me. I completed the training with 50.0 hours of total flight time, and 41.5 hours of dual instruction. Not too bad. Now I need to decide what to do next… instrument? dual engine? hmmm. At least I’ll have more disposable money for my other hobbies.


…eBay winner…

…So, I’m the proud new winner of a used eBay FT-897! I know, I’m excited too. I already can’t wait to get it. Should be here within a week or so.

And, what next? Hmmm… antenna. I’m thinking a really simple really portable string-up wire dipole antenna. Not necessarilly all band, but at least 20m and maybe 40m. Something that can be thrown up over the trees and operated on low power (for battery life).

Then, portability. Transport container. Something hard-cased like aluminum, or soft cased? Something hand-carry, or shoulder/back carry?

Of course, I’ll need another programming cable (I think) and programming software (definitely).

What about solar charging? Portable panels are getting pretty cheap nowadays.

Hmmm… and the habit addiction hobby expands…

…programming cable…

…So, I was looking at building my own programming cable, but changed my mind (for now). Instead, I purchased one – but not the expensive Yaesu one. I bought one off eBay from Valley Enterprises. It was just under $20, and shipping was FREE (yep, even to Hawaii – you never see that anymore).

I tried it out this weekend, and I love it. Of course, to program your radio you need software, and with only one C++ class under my belt, I wasn’t up to writing my own. So, a purchase and download from G4HFQ set me up with a great program.

Right now, I can only say that the cable works great, and that the software is really easy to use. I tripled the stations programmed on my FT-7800R in a short period of time at the computer. Best part is that it is completely organized now. The memories are setup in a way that make sense, and not just the order I entered them. Wow!

So, why didn’t I build one? I will. So far, it looks like I can cut a keyboard cable with a PS2 connector off, and that will fit the radio. As for the other end, there are diagrams that show the purposes of the different pins and wires, so it should be easy enough to mate that with an appropriate computer connector. Ah, but that is the problem. It looks like using a serial connector would be easy, but a USB connector (which I would rather use) has other issues. Since a USB port is a powered port, there are voltage adjustments that must be made. But, I don’t know enough about all that just yet. However, when I get bored enough… hmmm…

…joined EARC…

…Well, it’s been a year since I was licensed, and I finally made it to a club meeting ( I’ve had every intention of joining for quite some time, but only recently got around to it.

My first meeting was great. They did a PSK31 demonstration that was quite interesting. Definitely has some gears turning for me. I also picked up some cool stuff at the swap/shop after.

I picked up an inexpensive dual band mag mount mobile antenna (Jetstream JTM2P), some Power Pole connectors, a Power Pole power panel (Saratoga PP4), along with some wire and adapter connectors. So, it was a very productive evening.

Also, if you are out here in Hawaii, you know that parts are hard to come by, and shipping is expensive… Well, check out NH7QH’s store:

I was able to purchase the items online, send payment via PayPal, and he delivered them to the meeting the next night.

I’ve also signed on for NCS (Net Control Station) training. So, I’ll be able to help out with the nightly nets. Tonight, I’m going to check in via mobile to test the new antenna tx/rx. Next, I just have to figure out how invasively I want to setup the FT-7800R in my wife’s Liberty. I want to keep it portable, so permanent mounting is out, atleast for the main radio. I currently have the radio sitting under the drivers seat, with the removeable head sitting out on the console. It works well enough for a temporary setup, but I want something between temporary and full install… We’ll see…

…P Echo…AKA Oscar 51…

I received P-Echo last night. I attempted to answer a CQ on it, but tx/rx were pretty noisy. I didn’t quite make out the callers callsign, and though he heard me, he didn’t get mine either.

I hung around as it made its pass and heard several others answering the CQ. It was pretty cool to hear people using the satellite as it made its pass.

I was using a stationary dual band J-pole and a Yaesu FT-7800R. With a directional antenna, I know I’ll have a better chance at it. Looks like a homebrew Yagi will be on my list of stuff to do!

…heard first satellite…

…I think…

I believe I received PacSAT, AKA Oscar 16 today on 437.025.

Actually, I started getting an intermittent transmission on 437.030, and followed it for several minutes down to 437.015, where it faded out. I was using my Arrow dual-band J-pole. There was nothing for several seconds, then an electronic noise that lasted for about 10-15ish seconds, then nothing… and that repeated.

…homebrew antenna…

So, What do you do if you have a UHF SO-239 chassis mount coax connector and a bunch of croquet wire hoops sitting around… and you’re bored?

You build a 1/4 wavelength groundplane antenna!

groundplane antenna

First, collect the necessary parts… wire hoops and chassis mount UHF connector.

groundplane antenna

Then, straighten the croquet hoop wires.

groundplane antenna

Next, you’ll want to measure the wires for your frequency. Mine came out at about 19.25-19.26, since my target frequency is 145.800 (ISS).

groundplane antenna

What’s next? Cut the wires. (Note: some sites recommend leaving the radials up to 20% longer than the vertical element. I don’t know a lot about antenna theory, yet, so I split the difference and cut my radials to 19.75).

groundplane antenna

Remove the coating near the end that will mount to the coax connector for the vertical element, and clean up the metal wire with some sandpaper.

groundplane antenna

By pure luck, this is how well the wire fits into the end of the UHF coax connector. Beautiful! Add a touch of solder, and the vertical element is done. Be careful while soldering. The vertical element will carry a lot of heat away from the soldering iron, and I melted the plastic a wee bit. Of course, I’m using a crappy uncared for soldering iron…

Now the hard part… how to fit the radials to the chassis mount? If I had a die that small, I could have cut threads on the end of the radial wire, bent the end into an “L” shape, and mounted it to the coax chassis with a nut on each side of the hole. But, it was not to be that easy for me…

Solder? I was not having much luck doing any kind of soldering on this chassis mount connector. So that was out. After stewing on it for a couple hours and rummaging the garage, I came up with this:

groundplane antenna

Crimp-on wire connectors. These did not easily go on. I had to open up the crimp tube a bit with a nail to get them to slip over the croquet wires. Since there is no “give” in the croquet wires, the crimps don’t exactly work like crimps. So, this is a temporary solution since the wires will slowly work their way out of the crimps with a little jostling here and there over time. But, it allowed me to continue with the build!


Then, you put a little bend in the radials, and attach them to the UHF chassis connector.

groundplane antenna

Then, you cut a hole in the side of your PVC antenna mast base, run your RG-6 antenna cable, and test your radio!

So far, I have great tx/rx with the repeaters I can normally hit with my j-pole. However, I had no luck with the ISS, though it wasn’t a close pass… So, I’ll watch the passes, and try again on a closer one.

End result? I have a VERY inexpensive 1/4 wavelength groundplane antenna for very little effort! Great project.

…International Space Station…

Links to ISS information and tracking:

…built a power supply…

So, I finally finished the bicycle I was rebuilding, cleared some workbench space, and gutted a 300W power supply out of an old Antec computer case. I then converted it to a power supply for my Yaesu FT-7800R ham radio, to use as a base station in my garage.

This is a 300W switched power supply that supports 10A on the +12VDC rail.

Then I removed the cover.

Then clipped the unecessary wires and taped them off. The only one’s I needed for the ham radio power supply was the yellow (+12VDC), the black (ground), and the green (power on). I kept 1 green, 3 yellow, and 4 black.

You can twist the green and one of the black wires together. Be sure to tape them up and shrink wrap them. Also, tape the ends of all the clipped wires (just to be safe).

Then twist the 3 black wires together, and the 3 yellow wires together, and crimp an Anderson Power Pole connector on each.

You should have a pretty clean looking setup at this point.

Now, reinstall the cover, and you’re done!