KIX-OnlineLinks to amateur (ham) radio goodies on the web

Man, sometimes a topic starts going through your head, you do a little research and then start going all over the place.  This is one of them – antenna analyzers.  I’m a huge fan of them and run antenna clinics for our local club.  This tool is one quick way to get a snapshot of your antennas performance in a jiffy.

For those that have seen the MFJ analyzers, they basically consist of a low power transmitter and various circuitry to do the math and display the antenna or feedline information on an LCD screen.

Oztales strikes again with a very well done video.  The descriptions should give hams without an engineering background a very strong understanding of what is going on behind this “mystery box”.

While I’m “down under” let me show you a really neat analyzer kit that can be had for a fraction of the cost of the larger analyzers like the MFJ.  If you’re willing to burn a little solder, you can make a very sweet analyzer (I’m thinking of getting this kit as well, seems a good companion piece to my AADE LCR Meter).  As of this writing, the kit mentioned here costs $150.00 AUD for DX orders – which is a bargain!

As you can see, it has many things in common with the higher priced analyzers as far as layout and such.  Just keep in mind, from what I’ve seen in the picture and on their site, this is an HF only analyzer and does not have six meters – strictly 10 and up.

The kit is available from the South Coast Amateur Radio Club and on their website at:

http://www.scarc.org.au/kits.html

But……….

Across the pond, someone built one of these kits and you can get a really good idea of what is inside the kit.  This video is what is now making me consider purchasing this kit:

BYRONLOCAL’s Youtube channel has a few other videos that may be part of the kit (components) but I haven’t watch them yet, so check his channel if you want more information.

Oztales has scratched the surface of what you can do with an analyzer.  If you practice your google-fu, you’ll find lots of other great uses/mods for analyzers to expand their capability.

Now this is "homebrew"!!!

OK, I slacked off and missed a scheduled post last week, so I’m gonna give you a “twofer” this week with this well documented project.

Somehow, I stumbled on the website of NT7S, Jason R Milldrum.  His site documents the QRP-L project.  FANTASTIC WORK!

If you are interested in this project, there is a full build sequence (several pdf’s) which will make this an easier project for a new homebrewer.  Though, I think this is more of an intermediate project, the process is very well documented.

What is this project?  Let’s look at Jason’s site for more information:

The aim of the qrp-l.org Group Project is to provide members of the group with the opportunity to gain hands-on experience building and testing a QRP CW transceiver with like-minded individuals. The design will be a direct conversion rig with moderate complexity. The entire rig will be built from easy-to-find discrete components. This will make it relatively easy to obtain the required parts or make substitutions. It also gets away from the “black box” concept of some project, where much of the circuit action is enigmatic.

More information is available on his site at: http://www.nt7s.com/index.php5?page=qrplgp

Here is a block diagram of the project that would give you a pretty good idea of what to expect:

Jason has kept the site updated with regular posts regarding the current status of the project and also included audio files of the group EchoLink conference.  Now that’s really neat!

He also posted a YouTube video of his work in progress:

I’ve built several kits and smaller projects from schematics, I might just give this one a shot.  I’m looking at my parts bin and checking to see if I have enough to get started.

Thanx Jason for a well documented project!

Tektronix 465 O-Scope, commonly available online for a fair price

I know I’ve been tinkering around when I just spent a few hours looking at Oscope information!

I’ve been tinkering around a lot with QRP projects and some PIC based toys.  I’ve been wanting one on my bench for a few years now, but just couldn’t justify it – until now.

For past few years, more and more older analog scopes have been hitting the market in industrial surplus and on e-bay.  As companies are upgrading their equipment, many used scopes have been hitting the market for only a few hundred dollars.

I have found a bunch of decent videos and some good information on the Tektronix site.

First, I’m going to start of with a Wikipedia entry to give you some basic information.

An oscilloscope (commonly abbreviated to scope or O-scope) is a type of electronic test instrument that allows signal voltages to be viewed, usually as a two-dimensional graph of one or more electrical potential differences (vertical axis) plotted as a function of time or of some other voltage (horizontal axis). Although an oscilloscope displays voltage on its vertical axis, any other quantity that can be converted to a voltage can be displayed as well. In most instances, oscilloscopes show events that repeat with either no change, or change slowly. The oscilloscope is one of the most versatile and widely-used electronic instruments.

The rest of the information is available here: http://en.wikipedia.org/wiki/Oscilloscope This is one of the better writeups I’ve seen on Wikipedia.

Afrotechmods has a three part video set on YouTube that give a decent introduction to scopes with some really good advice as far as purchasing used on ebay and what is good for the home tech-bench.

AllAmericanFive radio has a neat intro to scopes.  He does a lot of videos on radio restoration and such.  VERY RECOMMENDED.

Found this neat older video here – still has good info.

Check out the Tektronix download here:  http://www.tek.com/learning/oscilloscopes/ You have to sign up to download from this site, but it is really worth it.  The sixty page booklet called “Oscilloscope Primer” is really worth reading.

There are a lot of sites out there with information on O-Scopes, this will get you started.

As usual, if you find any good links, please share with the rest of us and add a comment below.

**** late note/addition 4.24.09 ****

Based on a thread on the ‘zed, I have a few additions to add to the post.

The initial link from Tektronix (the one you have to register for) I think was for this file (direct download):

http://www.tek.com/Measurement/App_N…03W_8605_2.pdf

And here’s one that is a primer on probes:

http://www.tek.com/Measurement/App_N…60W_6053_9.pdf

Paul Harden, NA5N, has a few good, brief tutorials on his site:

http://www.aoc.nrao.edu/~pharden/hobby/Hobby.shtml

Here is his scope tutorial part 1:

http://www.aoc.nrao.edu/~pharden/hobby/Scope1.pdf

And here’s part 2:

http://www.aoc.nrao.edu/~pharden/hobby/Scope2.pdf

Fixed Bias

OK, I’m constantly learning new things as I tinker.  As I have stated in the past, I’m not an engineer and don’t do this on the day job – just a true amateur.

I stumbled on biasing as I’m learning a bit more about class A gear and studying “Q”.

I thought I’d share some of the resources I recently stumbled upon here and hope that others will post more information in the comments below.  There are also some good resources like ARRL handbooks that will give you a lot of good information.

I can’t believe I found several books on Q alone….. might I add, that reading is indeed…. a little bit dry!  I hope this stuff starts to sink in soon so I don’t have to fall back on my cheat sheets often.

First off, there is some Wikipedia information where the image on the right came from.  Including the following bit:

The operating point of a device, also known as bias point or quiescent point (or simply Q-point), is the point on the output characteristics that shows the DC collector-emitter voltage (Vce) and the collector current (Ic) with no input signal applied. The term is normally used in connection with devices such as transistors.

The Wikipedia page on bipolar transistor biasing here:

http://en.wikipedia.org/wiki/Bipolar_transistor_biasing

and another page on general electronics and biasing here:

http://en.wikipedia.org/wiki/Biasing this article is a stub though.  Why I would indeed advise consulting the ARRL handbook or something with much more information.

I also found this really neat article on transistor biasing at vintage-radio.com that has a short, but decent article:

http://www.vintage-radio.com/repair-restore-information/transistor_biasing.html

My YouTube friend AllAmericanFiveRadio has posted another fine video on Class A biasing basics:

If anyone has any really kewl links, please post them below.

OK, I admit, the past few weeks we’ve stayed heavily on the basics – but that’s OK (since I’ve been posting more!).

I’m sure the folks at Make: will have something in the near future (they’ve done really good with basic videos in the past).  But, today, I’m going to show you a whole bunch of YouTube goodness that I found.

First is RadioAM232.  He has a neat 3 video series below:

There is also a good lecture from India’s National Programme on Technology Enhanced Learning.  This is part two of an entire course.  I’ll add more information on this course in a future post (finding the entire course is a pain as I didn’t find play lists).

Here’s one more for good measure:

And, of course, the obligatory Wikipedia link to get you started.