Antenna Theory – another great video from OzTales

Filed Under (Antennas, New Ham Primer, YouTube Antenna Goodness, YouTube Goodness!) by Jonathan on 02-01-2010

This time I’ll keep it short and sweet.   “oztales” over at YouTube has a great antenna theory video.  Only runs about 10 minutes, but is packed full of good information.

This video would also make a great showing for new hams.  I run regular workshops and think this video will be in the normal offering.

Great work oztales!!!!

dB’s…..???

Filed Under (New Ham Primer, Reference Material, YouTube Basic Electronics Goodness) by Jonathan on 25-12-2009

First of all – Merry Christmas!!! and of course, Happy New Year…. OK, now on to the real reason you’re here……

Decibels are just one of those facets of our hobby that we need to know enough about in order to understand many concepts in radio.  As an amateur “engineer”, I didn’t know much before an audio internship at a PBS affiliate, and even then, I still needed to learn a bit more.

Enter….. the web.  Vast resource of useful information.

Wikipedia has a great article to get you started (this is just a snippet):

The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power or intensity) relative to a specified or implied reference level. Since it expresses a ratio of two quantities with the same unit, it is a dimensionless unit. A decibel is one tenth of a bel, a seldom-used unit.

The decibel is widely known as a measure of sound pressure level, but is also used for a wide variety of other measurements in science and engineering (particularly acoustics, electronics, and control theory) and other disciplines. It confers a number of advantages, such as the ability to conveniently represent very large or small numbers, a logarithmic scaling that roughly corresponds to the human perception of sound and light, and the ability to carry out multiplication of ratios by simple addition and subtraction.

The decibel symbol is often qualified with a suffix, which indicates which reference quantity or frequency weighting function has been used. For example, “dBm” indicates that the reference quantity is one milliwatt, while “dBu” is referenced to 0.775 volts RMS.[1]

The definitions of the decibel and bel use base-10 logarithms. For a similar unit using natural logarithms to base e, see neper.

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

I’d read the rest of that entry to get you started on your understanding of dB’s.

I won’t leave you there today, I found this really neat video on YouTube from Dave Jones of www.eevblog.com

As always, feel free to post any relevant information below.

XW-1 – new bird, lots of activity!

Filed Under (Space Communications, YouTube Goodness!, YouTube Space Comms Goodness) by Jonathan on 20-12-2009

OK, I was initially going to resist another satellite post, but it seems that they have generated a lot of traffic and there is a great new bird out there, the Chinese XW-1.

This is their first foray into the amateur satellite arena and there is plenty of information out there.

First off, let me give you the official link with information on the bird and the special event BT3WX:

http://www.camsat.cn

Now, you know I can’t just leave you with that, could I?????

Here is a China News article in English on YouTube:

This next video I found shows on neat aspect of satellite comms (this is the new XW-1, BTW).  It’s a simple video of a contact (mostly listening) with a camera on a radio.  But you get a real good idea of what happens to the bird as it flies overhead and an compensating for doppler shift:

This last one isn’t XW-1, but it’s a new satellite video from 2E0HTS and he demonstrates a contact made via V0-52:

As always, post a comment below if you know any more good links for the XW-1.

Sweet 6M Moxon from K3NG

Filed Under (Antennas, Six Meters) by Jonathan on 16-12-2009

Now, if you’ve been reading this blog at all over the year, you know I love homebrew antenna improvisations (like tape measure beams, etc).

K3NG homebrewed this neat Moxon and made some great instructions on his site.  Les Moxon had a great thing going and I do like the antenna (I also have one for six, recently destroyed, but I’m going to build the one modeled after K3NG).  These are great antennas for those of you that want to play a little on 2M sideband as well.

If you search my site, I have a post where we mentioned the Moxon Antenna Project.  They have a great calculator where you can plug in your desired frequency and it will give you dimensions for your antenna.

If you would like to see how K3NG built his (using plow stakes, gotta love it!), check out his site, here’s a direct link to his project:

http://thek3ngreport.blogspot.com/2009/08/homebrew-lightweight-6-meter-moxon.html

If you get the chance, check out his blog.  He has  a lot of interesting posts on various aspects of our hobby (dare I say /service!).

As always, if you have any interesting links on this topic, please post below.

More satellite antenna projects/improvements

Filed Under (Antennas, Homebrew, Space Communications, VHF/UHF, YouTube Antenna Goodness, YouTube Goodness!, YouTube Space Comms Goodness) by Jonathan on 07-12-2009

OK, not to sound like Rod Serling, but…..

Today, I humbly submit, for your approval, an incredible AzEl project from Dave Matthews, KI4PSR.

Dave has submitted a project to Parallax (the microcontrolller/stamp  people)  This is a neat AzEl setup that you can build from off the shelf parts (mostly) that allows you to use your computer to track the birds as they fly overhead.

It doesn’t get easier than this, but the project seems really neat.  He lists the materials he’s using as well as sites where you can obtain parts.

Might I add, he also brings my favorite Ham Radio Deluxe into the mix!

For project info, schematics and such, check out the Parallax website at:

http://www.parallax.com/tabid/787/Default.aspx

That might be a bit technical for some, but here are some other great projects/mods I’ve found recently.

K7PAR has some tips for improving an Arrow (or Arrow like) antenna at:

http://www.qsl.net/k7par/Articles/ArrowImprovements.htm

KI0AG has a neat micro duplexer for the Arrow.  He specifies that this is indeed maximized for the Arrow antenna itself.

What makes his project neat is he really documented the information well, so it is incredibly educational.  Check out his project at:

http://k0lee.com/duplexer.htm

Finally, let’s not forget Randy, K7AGE and his mod to hold a dual band antenna.

As always, if you have more ideas, post them below.

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