Archive for the ‘build’ Tag

…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?

Advertisements

…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!

…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!

…FT-7800R Portable…

I finally finished my portable setup!

IMG_0916

How portable? Well, the antenna, the pvc standoffs, the tripod base, the antenna cable, and the power cable all break down to fit in a croquet bag. The radio, mic, manual, and logbook all fit in a little fanny pack. To protect the radio in the fanny pack, it slides into a foam filter for a wet/dry vacuum.

IMG_0932

It’s a Yaesu FT-7800R with Anderson Power Pole connectors and 10ft of cable. To connect to a power source, I have 3 options: Connect to a car with a RigRunner (my wife’s Jeep, my Jeep). Connect to any car with the cigarette lighter adapter (not for extended operations, really just emergency use). Connect straight to a battery with the mini jumper cable adapter.

The antenna cable is 15ft of RG-6 coax, with the appropriate ends soldered/crimped on.

IMG_0937

The antenna is an Arrow Antenna OSJ 146/440 J-Pole. I paid the extra money to have the long element break down into 3 pieces. Both removable thirds of the long element screw into the angle bracket base for storage.

IMG_0930

The tripod base is an old rocket launcher made by a company no longer in business. Someone really should get the rights to this and make these again! Best part is that I didn’t have to modify the tripod at all, so I can still use it as a rocket launcher when I move back to the mainland… (no real rocket activity out here on Oahu).

To stand the antenna off from the tripod, I used a couple sections of pvc. If I need the antenna higher, I simple add another section.

IMG_0927

The whole thing needs less than 5 minutes to set up, and occupies very little space in the back of the Jeep. To take it elsewhere, simply put on the fannypack and throw the croquet bag over your shoulder. It’s all very light.