Archive for the ‘homebrew’ Category

…almost there…

Inspired by the success I had on field day using some (most) of n0oqa’s gear, I’ve made some purchases to get my mobile-deploy-able setup going.

First, I decided to go with a hitch mount push-up mast. Using Larry’s setup really sold me on the Max-Gain Systems fiberglass mast. I ordered the MK-4 Standard from here: http://www.mgs4u.com/fiberglass-push-up-mast.htm

Also, after seeing what it really means to have a tuner “talking to” the radio, I purchased a Yaesu FC-40.

My plans are to setup the FC-40 with the ladder line and deploy-able antenna as well as the coax and CAT lines to the radio, then stage all that in the bed of the truck. I have a covered bed and will have everything staged in a waterproof bag.

This will leave the CAT port of the radio for my BlueCat device. Since I’m primarily on VHF when on the road, this will let me work repeaters easily wherever I’m at.

When I’m somewhere I can park to do some HF work, I’ll get the antenna base mounted in the receiver, put the antenna in, roll out the FC-40/antenna/coax unit, hook up the CAT line and the tuner coax, get the pulley staged on top the mast, push-up the mast, guy-rope the mast, pull up the feedpoint, straighten and anchor the ends of the antenna wires – and I’m on the air.

This will be an inverted V antenna.

If I get a couple fiberglass painter poles, I can guy-rope them at the ends and raise the wire ends a bit. Getting them off the ground even 5 feet will help tremendously since my antenna center will only be about 23 feet off the ground.

Thoughts?

Advice?

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…new computer upgrade…

Yes, I was already unhappy with one aspect of my new system as soon as I was done building it. The video card. I originally bought two 3850’s to run a crossfire setup, but ran into problems due to the motherboard I selected.

Anywhoo, the single 3850 was working out great (as you can see from the pics in my previous post), but it wasn’t exactly what I wanted. So, I upgraded.

I have now installed a Radeon HD 3870×2! That’s a dual GPU card with 1GB of RAM. Upgrading to this card has more than tripled my 3DMarkVantage score from the low 2100’s to over 7400.

I’m also running dual monitors now. This single video card can support up to four monitors! For now, I’m getting used to two.

Here’s some pics so you can see how huge this thing is:

3870x2

These are the 3870×2 and 3850 cards side by side.

3870x2

Here you can see the four ports for the monitors.

I had to move some things around in the case (like move my hard drive cage up higher) to make room for this monster.

Oh, and here’s my new Call of Duty 4 Game-O-Meter score:

…new computer…

Well, I finally built a new computer. The old one is still hanging on, but it is time to go big. I bought the old one slightly used for $300, over 5 years ago and have only had to upgrade it’s RAM and video card. But, it’s days are numbered. Rather than wait, I got the pieces and parts and put together a decent system for not too much money.

Here’s the system (all parts purchased from zipzoomfly.com):

Case: old Antec full tower (like 8 or 9 years old)

Processor: Intel E8400 3.0GHz Core 2 Duo

Motherboard: Asus P35 chipset P5K-E

RAM: 4GB OCZ DDR2 1066

Video Card: Asus 512MB DDR3 HD3850 PCIe x16

Power Supply: CoolMax CUG-600B Green Power 600W

Hard Drives: (3) Hitachi Deskstar T7K500 500GB 7200RPM Serial ATA II w/16MB Buffer (I’m running the 3 drives in a RAID 5, so they are fast – but I also have drive failure protection. Basically, if any one of the 3 drives fail, I can change it out with a new blank drive and the information will be rebuilt from the other two drives. Pretty slick, huh.)

And, I believe, that’s the main stuff. After the combo drive, case fans, processor fan, LCD fan controller and card reader, etc. (oh, and shipping)… I spent about $1200. The computer benchmarks pretty high.

However, I’ve already learned a couple lessons, and if I could go back and do it again already – I’d get a different motherboard. I had originally purchased 2 of the Asus 512MB video cards, planning to do a dual CrossFire system. However, the P5K-E, though it advertises that it supports CrossFire and has two PCIe x16 slots, doesn’t support two cards at x16. Confusing, huh. Apparently the fine print states that the second PCIe x16 slot only runs at x4. So, what a waste. I sold the second video card and am only using one.

Here’s where my system benchmarks for a popular game, Call of Duty 4 (which I don’t play – but was told to check my system against it):

Call of Duty 4 benchmark

And here’s a couple of screenshots from Flight Simulator X. I can’t believe how much better this runs. It is truly amazing!

So, that’s it! What do you think? I’m pretty happy with it…

…DIY Alcohol Stove…

In our emergency and portable kits should be some way of emergency cooking. For me, I’ve been playing around with ultralight stoves made out of pop cans. I have finally settled on a design I like. It works well, burns just about anything (isopropyl alcohol, denatured alcohol[recommended], methyl alcohol, heet antifreeze – basically if it burns you can use it), and is small and portable.

http://back2dabike.wordpress.com/my-rides/tour-of-oahu/homemade-stove/

I have the instructions, photos, disclaimer, and video posted on my biking site via the above link.

Please let me know if you try it and how you like it!

73’s!

…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!

…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…

…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!

ground

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.

…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!

…build a power supply…

Here are some articles on converting a computer power supply to a 12VDC power supply (for something like Ham Radio):

Can you guess what my next project will be? 🙂

**UPDATE**

I converted a 300W ATX computer power supply to a ham radio power supply. See this blog entry for all the details:

https://wh7da.wordpress.com/2008/01/08/built-a-power-supply/

…crimping Anderson Power Pole connectors…

…so, I’m sitting around in my garage without a fancy crimping tool to properly crimp the Anderson Power Pole connectors I’ve learned to appreciate. In the middle of grinding down the jaws of a little used set of pliers, I had an epiphany. Here is how to crimp these connectors with standard crimping pliers and a small nail.

crimpers

Your crimpers or whatever pliers you are going to use should have a somewhat round area. Mine have the area behind the wire cutter labeled INS.

tools

Other items you will need are the connectors on the ends of the prepped wires, and a nail.

set up for crimping

Simply align the seam of the connector along the top of the crimper, and carefully lay the nail along the seam of the connector.

crimping action

As you squeeze, the nail will force the seam down into the wire.

However this will also slightly flatten the connector.

So, rotate the crimped wire 90° and sqeeze again to obtain the desired shape.

crimped wire

At this point, you can lay a little solder in the connector. I don’t use too much, just enough to keep the connector from ever working loose.