Tag Archives: Amateur

KK4FGM on the International Space Station (RS0ISS-4)

Screen capture of ariss.netEarlier today I took a shot at communication with the UNPROTO side of the ISS’s amateur radio communication system. I would give myself a C- for operation because I made a few mistakes, but I was brought up on www.ariss.net. The funny thing is that it put me right in the sea below Iceland. Thanks to my friend Thomas for pointing that out to me. I am not running APRS yet. I haven’t quite figured out if Ubuntu can do that for me.

You can see that my message was longer than my packet length of 72. It was split, and with the busy system it was spread out over several seconds or minutes. I will shorten the message next time.

I issued a public apology on issfanclub.com for not using good operating procedures and not knowing what I was doing. I wasn’t intentionally trying to make a mess, but nonetheless I feel awful for tying up the line for longer than I needed.

Once I figure out this stuff good enough, I plan on blogging about the experience so that perhaps the knowledge can be spread. I am using a Yaesu FT-1900, a Kantronics KAM TNC (bought used…I think it’s somewhat old), and an HP laptop running Ubuntu 11.10. I have a cheap USB to serial adapter to connect the TNC to the computer. I didn’t receive any cables with the TNC when  I bought it, and I had to wire all those up, too. That was fun, and it only took two tries to get them right.

I hope to see everyone on the ISS, soon. Not literally everyone, but to those who work it, I’ll be there as much as I can to say hi. Perhaps someday I can get an APRS system going, too.

Portable Yagi Antenna Stand (Using the Arrow 146-4BP)

For Christmas my wife bought me a “backpacker” Yagi antenna made by Arrow. It is the 146-4BP, and it consists of a 3 piece boom and four elements. I wanted to use this as a portable antenna, but I missed out on one thing. I didn’t tell her to buy the mount. The mount is only $9, and is very well designed, but unfortunately after shipping would cost much closer to $20, so I decided that I would forgo that.

What I decided to do was to drop back and return to my PVC days. Instead of a potato cannon, I would make something much safer.  I went to the hardware store and purchased a handful of items.

  • stick of 2″ sch40 PVC pipe
  • 5 – 90 degree 2″ elbows
  • 3 – 2″ cleanout tees
  • a pack of 3/4″ conduit clamps (Need 2)
  • I already had a few washers and screws

Cut the PVC pipe to the lengths in the first picture. These should be two 15″ lengths, four 2.5″ lengths, and two 5″ lengths. The great thing is that you are not limited to these measurements. If you want a larger base, modify the cuts. Just keep in mind that the center piece relies on the two long pvc cuts. They need to be snug so that they don’t slip out.

For the antenna clamp, I used the conduit clamps to hold the antenna into place. This is most effective as a vertically polarized antenna, but may work alright as a horizontal. I cut a piece of 2″ PVC for this, and I didn’t measure. I just made sure that the clamps were in line. The second photo shows how to make this work. I had to bend the clamps down to the PVC to get a good grip. Using some rubber sheet would have made this connection a little more snug. I also cut a notch out the the elbow so that the boom didn’t bind against it. You can barely see this notch in the photo.

Finally, I used the remaining length of 2″ pipe as the mast.

This whole project cost less than $20 dollars. The elbows were 88 cents each, the tees were $1.50 each, the PVC pipe was about $7, and the clamps were about $1.50 a pack. The screws were free.

Antenna Mast BaseAntenna ClampLooking down the mastAntenna Stand

Directional Antenna Compass Using Inkscape

Screenshot from Inkscape showing compass stripI was telling my cousin, Ken, about my antenna, and I mentioned that I lost my compass that I was using to direct it and I was estimating where certain repeaters were located. He gave me a good idea. Why not print a strip of paper with the degree marker to wrap around the PVC pipe?

Great idea. I’ll put a tick mark on my mast (the part that doesn’t move) and then glue the strip to the rotating portion of the mast. Then I can align it up one time using a compass, and then I’ll have a quick and easy way to align the antenna after that. He discussed soaking the paper in a super glue mixture, but I think I will just use some clear tape to secure it.

The first step is to find the circumference around the pipe. Pi*diameter. For my case, the circumference is 5.215″. In Inkscape I chose to use pixels as the measurement. The resolution is 90px per inch. The length of my compass will be 469.35 pixels, and each 1.30376 pixels is one degree. Using guides in Inkscape, I marked out ten degrees with vector lines. Then I copied those ten (including the zero mark) and pasted them. After aligning the zero and the ten mark, I copied the twenty degrees and pasted them. After aligning I copied the forty and pasted. Now I have 80 degrees pasted. Then 160. Then 320. Then I pasted 160 again and deleted all those that came after 360.

Now I just have to print it and affix it to the mast.

The Junkyard 2m Yagi works!

Azimuth map - http://ns6t.net/azimuth/azimuth.html

The other day my uncle came up with a neat little design for a light pole that he moves around the shop. It uses a 1.25″ pvc compression coupling. I used one of the threaded ends to connect it to a 2″ cleanout fitting. The threads fit close enough that it screwed together. This is so that I can pack the antenna and mast up and move it. It actually carries around quite nice.

Pictures are a must, and I will post them soon. I just wanted to blog that I was able to hit the KE4URL repeater with 2.5 watts (which I estimate at 40+ miles). I also hit WG4JOE’s repeater which is located in Parrot, Ga.

I was able to get the side tone through KE4URL, but at 10pm, nobody was talking. I marked the spot with a marker on my mast, then I estimated that the other repeater was at about 10 degrees based on a contact that I made while mobile on that repeater.

WG4JOE answered, but he informed me that my transmission was hardly intelligible. I climbed the ladder and turned my antenna about 10 degrees towards the west and gave my call sign again. He almost caught most of it, but he heard Moultrie and suggested that we switch to my local repeater to talk.

While on the local repeater I could use a half watt with no worries without directing my Yagi. I informed WG4JOE that I was using an HT with a low battery and that my antenna was pointed at 10 degrees North then 0 degrees North, estimated. He said that I would probably get a better copy if I turned the repeater to about 310 degrees or so. After looking everything up, it appears that he was about spot on. 310-320 degrees. I will try that some day this week and see what the results are.

Another thing to note is that feed lines make a big difference. I had been using a cable that was coupled together, and the losses are pretty insane through the coupling. A single piece is the way to go.

I am very happy with my scrapyard Yagi. Even though the Yagi wasn’t pointed directly at WG4JOE, that was still a 100+Km contact.

MFJ-841 2 Meter SWR and Power Meter

Shows the selection switch, connections, and sensitivity pot

Rear view of the MFJ-841 SWR/power meter

With my first purchase of ham equipment, I decided that I couldn’t live without a simple SWR meter. I did some shopping and made my purchase based on price alone. For the last couple of weeks I was not sure if I made a good purchase, but I decided to email MFJ with a question, and now I know that I did a good thing.

I paid about $50.00 for the MFJ-841 from hamradio.com. I had already built my 2 meter vertical dipole and I assumed that it would have a good SWR so I raised it on it’s 20 foot pole and secured the guy wires. This was all done a few weeks before my call sign came in so I couldn’t legally test the antenna’s SWR by transmitting.

It was when I could legally test the antenna that I became confused. I followed the directions that came with the meter, but I did not understand what “setting the switch to
SEN (sensitivity), keying up and adjusting the meter for maximum needle
deflection” meant. Did it mean setting the needle to the end of the printed scale, or did it mean setting the needle to bend against the meter case? I assumed that it meant setting the needle to the end of the printed scale, but when I did that I had a 1:1 SWR on my antenna at 146MHz. I doubted that it was that good! I was hoping for the best and preparing for the worst, which would mean bringing the antenna down and cutting the caps off to trim the copper for the best SWR.

After emailing MFJ, they confirmed that the needle should be set to the end of the printed scale and not bending the needle at ‘max’ deflection. If I wrote the directions, I would have put a picture as an example since I believe that max deflection sounds like the needle needs to go as far as it can. Their definition of ‘max’ means the maximum that the printed scale shown extends. I learned something valuable today, and with this information I am going to test all kinds of antennas for 2 meters!

I want to finish with photos that I took using my new knowledge, but I want to say that MFJ has quick customer service. I also want to thank them for providing downloadable user manuals and for including the schematic for this device in that manual.

Five watts

FT-60 Xmit power shown on the MFJ-841

This 2 meter dipole has a great SWR across the whole 2 meter band

Graph of SWR using data from MFJ-841 SWR/power meter

This is bending the needle!

Wrong setting for sensitivity

This shows the correct setting. The meter needle is at the end of the scale.

Correct setting for sensitivity

My 2 meter vertical dipole's swr @ 147.960MHz

My 2 meter vertical dipole's swr @ 147.960MHz

My 2 meter vertical dipole's swr @ 146.190MHz

My 2 meter vertical dipole's swr @ 146.190MHz

My 2 meter vertical dipole's swr @ 144.830MHz

My 2 meter vertical dipole's swr @ 144.830MHz