Sunday, January 25, 2015

St. Louis/Collinsville IL Winterfest 2015


I wasn't planning on going to a hamfest in January. Oh, I've thought long and hard about making the flight down to Orlando in February, but that's just not going to happen this year. You see, I'm one of those middle-aged ham radio operators that still has a day job to support my family AND my hobby! 
But my "buddy" Fred KC9REG convinced me that I just had to go to Collinsville this weekend.

So early this morning (4am!) I was up and getting out the door to meet Fred and two of our other co-hearts in crime as we took the 2.5 hour drive from Central Illinois down to just this side of St. Louis. And boy, was I glad I went! Winterfest is put on by the St. Louis & Suburban Radio Club and is proclaimed as the biggest, oldest, and most successful hamfest in the Midwest. All indoors in the Gateway Center, the fest offers a little bit of something for everyone. There were the typical vendors, lots of flea market tables, and displays by various organizations.

I spent some time at the Missouri Digital Group booth talking with George WB0IIS about their work with D-Star. We swapped stories and talked about the growth of this technology in both Missouri and Illinois. George had a working Icom stack on display. I showed them pictures of our homebrew repeaters to which they pointed out that in 2005 they didn't have access to the open source software and alternative hardware that we do today.


I escaped the fest with only a few minor purchases...some powerpoles, a speaker, a rocker switch for a project, and a $5 bread box sized vhf duplexer. Anyone that knows duplexers for VHF will tell you that you don't find them for $5. This one was a small unit that had been used for some Civil Air Patrol work. If nothing else, it will make a good enclosure for a random project.

All in all, it was a great adventure. I wouldn't be able to guess at attendance, but it was definitely worth the trip. Anytime you get to spend time with friends and get to make new ones is time well spent.

Wednesday, January 21, 2015

A quick sprint

I was very time limited this evening, so I only spent a few minutes on the NAQCC cw sprint for January. I worked AA7VW Vern in Oregon, and KD3CA Don in Pennsylvania. My last two sprints had quite a few more contacts, but I also worked all two hours then. Work ran long, and then after a late dinner I found myself in the shack working on two fixit projects that I didn't want to put off another day! I turned on the KX3 and listened to the melody of cw while soldering a new connector on a mic and fixing a fussy (but new) power supply. If you're looking for a fun little contest, I'd recommend trying the NAQCC monthly sprints. Even if you're not a member, you're always welcome to join in.

Tuesday, January 20, 2015

So you want to build a DSTAR repeater...

So you've played with DSTAR enough that you've decided you want to host your own repeater. Well congratulations! Welcome to one of the most challenging and satisfying activities in your ham radio "career"!

Here's what you'll need if you want to build a DSTAR repeater.

1. Antenna
2. Feedline
3. Lightening protection (suppressor, in addition to a proper ground system)
4. Duplexer (a flat-pack mobile unit will work if you're in a low RF environment. If there are other transmitters around, you'll want larger cavities - a band-pass/band-reject unit.)
5. A repeater site - as high as you can get, with easy access for maintenance
6. Internet access - including a public facing ip address so users can route directly to you from other repeaters
7. Power supply - 12V at whatever amps you'll need
8. Miscellaneous cables...all good quality!

As a quick side note, all of the principles for analog repeaters applies to digital systems. Checkout www.repeater-builder.com for tons of good information.

Phew. Now that you're done with the antenna system and internet access, you'll need to make a decision. Are you going to go with the ICOM system, or a home-brew system?

For an ICOM system:
1. Radio module for the band you want to be on ($700 for UHF)
2. Controller module ($850)
3. Computer running Linux to run the gateway software (figure $300 for a solid system)

That's $1850 in addition to items 1 through 8 above.

The other option is a home-brew system. I've built two of these already - one from Kenwood radios, and one from Motorola radios. Either of these requires access to programming gear/software, so you may have other costs you need to consider.

For a home-brew system built on Motorola radios:
1. 2 CDM 1550 UHF radios (one for TX, one for TX) - $300 from eBay
2. Raspberry Pi with SD Card to run the G4KLX gateway software ($50)
3. DVRPTR modem - http://dvrptr.net/ ($120)

For the CDM radios, you can't run them at 100% power - these are mobile radios, and they are rated at 50% duty cycle or lower at full power. I'm using 30 watt radios at 10 watts. The transmitter doesn't seem to mind this power setting, even when run for 2 hours continuously. Because of the acknowledgement packets that are sent after user transmissions, duty cycles easily get 100% during normal DSTAR use. Hold a net, or a long QSO, and you'll find your transmitter melted if you try to run it at too high of a power setting.

You can add a power amplifier after the transmitter if you need more power. I've not found this to be necessary with the proper antenna and site. If I can hear the remote units, they can hear me. More power hasn't been necessary.

I've also had success with a Kenwood TKR-820 repeater. But....programming these for me is harder. Alignment is a bunch of coils and takes some time. They have a built-in power supply. You really need to narrow-band the units, as that's what the users' radios are expecting. It will work wide-band, but it won't work as well. The system needs to be narrow on both the repeater and user side.

Friday, January 16, 2015

Climate Change

One of my many hobbies is the watching of weather. I really started to get involved with weather while I was in college, working for WTHI AM and FM. Watching the weather was important while I was on the air...but was even more important when I was "playing engineer". I needed to know if the tower was likely to get hit by that big thunderstorm rolling across Illinois!

So when we moved to the flatlands of Illinois, I bought a weather station. It's a Davis Vantage Pro...wireless from the sensor to the main unit. I hooked it up to share the information via Weather Underground. Pretty neat stuff - they store the data, and I can go look at it from anywhere I want.

http://www.wunderground.com/personal-weather-station/dashboard?ID=KILHEYWO1

Recently I've got all of the information being forwarded via the weewx program on a Raspberry pi. Very minimal power utilization by the pi...so I'm reducing my carbon footprint. :-)

But here's the rub. The Weather Underground guys are full-on climate change proponents. It's in your face, how could you possibly doubt, we're the scientists and you're dumb doubters... It is yucky.

I'm a doubter. I'm with my oldest daughter that believes that the climate is changing, but by how much and because of what is in doubt. As she goes through college that may change. I'm a strong believer in God. He has a plan, and he controls the universe. That's in conflict with a lot of climate change, and most scientists in general.

Regardless, the KILHEYWO1 weather station will continue to send its data to Weather Underground. It's a good site, great availability, and free to use. I'm glad I live where anyone can have any idea they want, and capitalism wins.

Tuesday, January 13, 2015

Remote access to Raspberry pi

Just wanted to share a service I'm using to manage my raspberry Pi(s) remotely. I don't have any financial interest in this service....It's called Weaved.com and is focused on the Internet of Things. If you have your Pi exposed to the internet, and you're allowing incoming connections to ssh, you probably don't need this. But if you don't want to do port forwarding on your router or you can't (don't have control of the router, don't have a public IP on your router) then take a look at Weaved. 

I've set my two dstar pi repeaters up so that I can use WebSSH, ssh, and VNC. It's pretty simple to setup, and is free for a limited number of devices/ports.