New Project: WA2EUJ Amplifier

A couple of years back after a lot of research I took the plunge and bought a Flex 1500 Software Defined Radio. This QRP radio is a really fine machine and I enjoy it very much. Although I also like QRP operation there are times, especially on SSB, that a little more power would be nice.

WA2EUJ won the ARRL Home Brew contest a while back with a neat little 50W amplifier design. He has since updated the design to include filtering for 80-10 Meters and there is a professionally produced printed circuit board available for this updated version. I've decided to build this amplifier and will be documenting it here as a series of posts. I have the bulk of the parts on order and hope to begin as soon as the bench is cleaned off!

Update: January 15, 2012. Several people have asked about where more information can be found on the updated project. Current bill of materials, schematics, etc. are available on the ARRLHBC Yahoo Group. Several other projects are discussed there as well but the files section is a treasure trove of information about the PC board, tuning, etc.

73,

Tim N9PUZ

The Old Reliable UHF Connector. Is It Really?

One of my favorite blogs is that of KB6NU. He always offers up a good selection of interesting things found on the web and elsewhere. Today he mentioned this article which details some tests done on the common PL-259 connector designated a "UHF". Read more in the 'UHF' Connector Test Results.

73,

Tim N9PUZ

Exploring USB Devices

The 9-pin or 25-pin D-Sub type serial port connector is going the way of the dinosaurs on most computers these days. Yet, the people who make add-on gadgets such as TNCs, antenna controllers, etc. still crank out products that require a serial port connection. Fortunately a lot of companies make USB-to-Serial converters. Some even make good ones.

I don't claim this is a scientific evaluation by any means. It is just my observation. While any USB-to-Serial converter may work in some cases it is my experience that those with an FTDI or Prolific chipset inside them will always work.

Anytime I buy a new USB-to-Serial adapter I try to buy one that tells me what chipset it uses. Then, if I have a choice, I usually get the FTDI variety mainly because they were some of the first ones I found to work well and they provide good support and information.

But what if you have a device and have no idea what it uses? Knowing the chipset manufacturer may help you troubleshoot a problem. Microsoft has a neat little utility circa 1968 called USB Viewer. It will show you all of the USB controllers and hubs in your system plus in most cases it will identify whose chipset is inside them and even what model chipset in some cases. In the picture below I've plugged in an adapter with a Prolific chipset.

This utility is available free. Download USB View from the FTDI Website

Happy hunting!

73,

Tim N9PUZ

32-Bit Power Comes to the Arduino World

If you've ever wished you could have a little extra horsepower for your Arduino project then this may be just the thing. Digilent Inc. has a new 32-bit chipKIT product. One version features the Microchip PIC32MX320F128 and the other a PIC32MX795F512. Both are MIPS processors. Details are found at the link above including where to download a compatible development environment.

The PIC32MX795F512 on the chipKIT Max32 board supports Ethernet, CAN bus, and full USB 2.0 connections.

73,

Tim N9PUZ

Comparing Base Station Antennas

Sometimes you read about something in a book but you don’t really give it a lot of thought. Recently I had a chance to observe the performance of two different antenna types and I can confirm that the design differences can really affect the performance.

On my tower at home I have two dual-band VHF/UHF antennas. One is an Arrow Ground Plane @ 55ft, the other is an Arrow J-Pole @ 45 ft. Both are fed by the same type coax.

One evening I was trying to use the W9BIL D-STAR repeater in Cadwell, IL which is 49.1 miles from my house according to QRZ.com. The ground plane is normally used by my Winlink RMS Station and the J-Pole is normally on my shack’s dual band radio.

I was pleased when I was able to key up the repeater operating with the J-Pole although the signal strength meter barely moved. I switched to the ground plane antenna thinking the extra 10 foot or so of height might help a little but to my surprise I could not hear W9BIL at all. I never thought much about the antennas being all that much different and assumed that height would trump anything else.

Some research was in order.

Discounting the difference in height which should have helped if everything else was equal there are two other factors that come into play:

• Antenna Gain

• Angle of Radiation

Let’s look at three antenna types: a simple ground plane, a J-Pole which is a 1/2 wave antenna and a 5/8 wave antenna which is another popular style for VHF/UHF.

Antenna Type	Reference Gain	Angle of Radiation
1/4 Wave Ground Plane	0.0dB	25°
1/2 Wave J-Pole	+ 0.85 dB	20°
5/8 Wave	+ 2.35 dB	16°

The lower radiation angle puts more of the power you’re radiating at the horizon. The higher gain means the antenna pattern is also focusing the power in the most desirable direction.

For the curious, going longer than 5/8 Wave tends to hurt your cause. Beyond that length the radiation angle begins to increase.

You may be wondering why I included the 5/8 Wave antenna when I didn’t have one to compare. Well, it turns out several companies like Comet make nice 5/8 Wave antennas for Amateur Radio use at fairly reasonable prices. You never know when an upgrade may be in order!

  

73,

Tim N9PUZ

D-Star Progress

W9DUA D-Star UHF Gear

The Sangamon Valley Radio Club's new D-Star repeater continues to move forward. The repeater itself won't move to its final location until the end of July/start of August but the gateway is now operating full time and accepting self-registration. If you are a new D-Star radio owner or DV-Dongle user in our area and are not currently registered in the D-Star network please join us!

W9DUA D-Star Self Registration

73,

Tim N9PUZ

Web Site Updates

Happy Independence Day to all of you in the United States!

I made a couple of minor updates to the main web site today. First, I got an email from Chris NØTTW telling me that the Programmable ROM I mentioned in my article on updating the KPC-3 TNC is no longer available. Second, I freshened up the listing of programs that are suitable for doing Winlink 2000 email here in Sangamon County, IL.

73,

Tim N9PUZ

Watson, Come here! W9DUA D-Star Repeater

Today was a major milestone in the Sangamon Valley Radio Club's D-Star repeater project. We got the controller, UHF repeater, and duplexer mounted in the rack and did some initial configuration of the basic system with a temporary antenna.

Around 4:30pm central time N9UWI and I had a successful digital voice QSO through the repeater.

Next order of business will be to get the gateway computer installed and reguster the system on the US Trust Server to allow Internet linking, etc.

73,

Tim N9PUZ

2011 ARRL Field Day

I spent most of Field Day with the Sangamon Valley Radio Club in Riverton, Illinois. The best way to describe it overall was wet. It rained lightly on and off while we were setting up. Then just before 1pm local time the lightning and thunder began. People operated on and off as conditions permitted. We did have a good time which is important.

Shelter was plentiful. The school at Riverton where we operate makes the cafeteria, restrooms, etc. available. A few people even operated from inside with cables run out the doors to the temporary antennas. The weather may not have cooperated but it was still a day of fellowship and fun.

 

Don N9ZGE (Left) and Rudy KC9LSM (Right) look on while Don W9EBK tends the grill.

Vicki KC9JPQ

Bob NA9GW

 Roger K9LJB

 Teri K9TLM (Left) and Claudia N9HHE (Right)

Tom W9EBY

There were a lot more club members present, I just didn't get many pictures taken.

73,

Tim N9PUZ

Kudos to Ameren Illinois

This morning we lost power during a thunderstorm. The repair crew said they thought a lightning strike took out the breaker on the pole with the feed for our house. We lost power around 6:30am. They stopped at the house around 8:00am to say they were out of the part on their truck and had to go replenish their supplies. By 9:30am or so we had power again.

Pretty good service I think.

73,

Tim N9PUZ

The Poor Ham's Radial Plate

A lot of discussion around building an HF vertical includes talk of a "radial plate" to attach your radial wires to the ground side of your feedline. There are several commercial offerings that look similar to this one from LDG (S9 Antennas):

These are all well and good but they strike me as being a little pricey for what they accomplish. With a little effort and a trip to the hardware store for a piece of aluminum flat stock you can get enough material to build several for about $10 or less. Fabricate yourself something along these lines:

When I originally sketched this I indicated 2" wide flat aluminum. In fact 1" wide stock or even 3/4" would probably work as well and will be less expensive.

------

Well, ideas abound on simple solutions to this. My buddy Scott NE1RD sent along a link to show the technique he used on the 40 Meter vertical at his new house. Not only is it economical but you don't have to drill any holes yourself!

Plumber's Strap

73,

Tim N9PUZ

Easy Ethernet Connections

There was a time when I could attach an RJ-45 plug to a piece of CAT5 cable very quickly and without a great deal of thought. That has changed over the years. Now that my eyes, as well as the rest of me, have made 55 trips around the sun I find that things are'nt quite so easy as when they were "less experienced." Getting the wires ready, cutting them to just the right length, fitting them into the connector, crimping, and then trying to see if all eight have a good connection can be a chore. Fear not aging geek, there's hope.

The folks at Bowmar Interconnect have a new RJ45EZ connector. The design is very simple and pure genius. Have look here:

The end of the RJ45EZ has holes in it. You strip the jacket back so you have plenty of wire to work with. Then you thread each wire through the proper hole. Once you verify they're correct you crimp the connector in place and finish up by trimming off the excess wire.

The Bomar connectors are carried by most of the regular suppliers such as Digi-Key, Allied, Mouser, etc. I did a search around the time I wrote this post and found the least expensive price at CMH Electronics in Canton, OH. Single pieces were around $1. The part number you want is Bomar 300668EZ.

In addition to their intended use the RJ-45 is also common on the microphone cords of many amateur radio products. Having a few of these on hand for repair work could save you from having to buy an expensive cable from the manufacturer.

Now, if I could just quit forgetting where I put down my glasses...

73,

Tim N9PUZ

SparkFun Electronics

A lot of us like to tinker and build and several people have mentioned getting cool stuff from SparkFun Electronics. I'm always interested in knowing how neat companies like this got started and how they operate. Recently, the 37 Signals blog Bootstrapped, Profitable and Proud did a piece on SparkFun. It sounds like an interesting place to work. Heck, you can even bring your dog with you!

Nathan Seidle (left, in a photo from CNNMoney.com)













Keep on tinkering!

73,

Tim N9PUZ

Past Projects

This post was inspired by a hamfest purchase. Earlier this year I stumbled across an old issue of Circuit Cellar Ink and just had to buy it.

When I first studied electronics in school microprocessors were really expensive. Little 8-bit chips were hundreds of dollars so the community college I attended certainly didn't have any in the lab for us to play with. In the mid 1980's I'd wait for each new issue of BYTE Magazine to arrive and would immediately go to Steve Ciarcia's Circuit Cellar column. Those articles were the basis of my self-education in learning how to design and program what came to be known as embedded systems.

One day I saw brief mention that Steve was looking for people to be a part of his research staff. What the heck, it would be fun to at least apply so I sent off my letter... this was pre-Internet after all, at least as we know it today. A few weeks later to my disbelief Steve himself called on the telephone to discuss things and I became part of the staff which is another story entirely. I'll save that for a different day.

Eventually BYTE was purchased by McGraw-Hill and their battalions of attorneys wasn't too keen on the idea of Steve telling readers how to modify electrical equipment or even build their own from scratch. A new magazine "Circuit Cellar Ink" was born and the researchers followed our leader.

In those early days articles were needed to fill the pages while word spread. My friend Dennis WD9EEK and I co-wrote an article called Stepping Out, A Robot Arm that Demonstrates Microprocessor Control of Stepper Motors. It appeared in the July/August 1988 issue of the magazine (Volume 1, No. 4.)

 
It was a lot of fun being part of the research staff and a lot of fun working with Dennis on the project. Up until that point I'd never used a stepper motor before but I was a lot younger at the time and my attitude towards most new challenges was usually "How hard could it be?"

I hope you've had some fun projects both past and present.

73,

Tim N9PUZ

Quality Audio Connectors

A pet peave of mine is cheap, crummy connectors. They are often difficult to install plus they frequently cause all sorts of tough to diagnose intermittent problems. Recently I came across some really high quality 1/8-inch (3.5mm) mono and stereo connectors from Neautrik/REAN. They are available from Mouser in the US and undoubtedly many other suppliers as well. Cheap connectors are often well less than a dollar. These are $1.50 or more but you build a cable with one once and it just keeps working. A wise investment in my mind.

The mono plug is P/N: NYS226BG. The stereo version is P/N: NYS231BG. These are the real deal. Black metal handles, gold plated contacts.

73,

Tim N9PUZ

Always A Thrill...

Yesterday's postal mail brought one of my favorite things. New magazine? No. New catalog full of new toys? No. The letter carrier brought an envelope from the Northern Illinois DX Association . NIDXA is a DX club but they also run the 9th District Incoming QSL bureau. The envelope contained a dozen QSL cards from stations in Columbia, Poland, Greece, Spain, Croatia, Italy, Germany, France, and French Guianna.

I am not a big time DXer nor do I have anything approaching a superstation. Most of the time I run 100 Watts or less to an "all band" 80 Meter dipole fed with balanced line. Occasionally I'll use my amplifier on SSB but that's a rare event.

When you first get your HF privileges any contact is a thrill. If you spend a little time to learn more about propagation you'll find that a lot of the time your timing is more important than anything else. You increase the likelihood of DX contacts tremendously by knowing when to listen. Are you on a band with possible propagation at the time of day when it should occur? Is it a time of the day or week when the DX will be around, i.e.--not sleeping, not at work, etc.

Often, good times to listen for DX are the few days before a big contest. The frenzied atmosphere of the contest hasn't begun but lots of stations are verifying that antennas and equipment work, etc. You'll also find that the DX is more likely to engage in an actual conversation outside of the contest. On the other hand, don't be put off with just a short signal exchange and a 'thank you'. In many cases the operator on the other end may not actually speak English and has made an effort to learn just enough to make a contact.

73,

Tim N9PUZ