VHF/UHF and microwave antennas de G4CQM

Filed Under (Antennas, Homebrew, New Ham Primer, Six Meters, VHF/UHF) by Jonathan on 29-03-2010

If you’ve been reading this blog for awhile, you know I’m a huge fan of not only making your own gear, but projects that can help new hams get started making their own gear.

G4CQM has a great compendium of VHF/UHF and microwave antennas that any new ham can build and use.  There are some great antennas for 2M that can be used for either hitting a distant repeater, making a good haul on “52” or even satellite work.

Many of the antennas in the microwave area can be modified for computer/wifi use as well.  Really neat stuff.

Some examples are:

6 Meter antennas from 5-11 elements

2 Meter 3-11 elements

70, 23 and 13cm antennas

Information on feeding, stacking and feed loss

The overall construction articles are well written with plenty of nice drawings as well as antenna plots.

If you would like to check out G4CWM’s Yagi antenna site, point your browser to:

http://myweb.tiscali.co.uk/g4cqm/

Link update:

G4CQM has sent me a new link as he has changed ISP’s:

http://www.qsl.net/g4cqm/

Thank you Derek for keeping me honest!

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.

An introduction to six meters

Filed Under (New Ham Primer, Six Meters, YouTube Goodness!) by Jonathan on 02-06-2009

I have heard A LOT of new hams on the repeaters lately – that is a good thing.  I haven’t heard much discussion about life beyond the repeater.  This is why my tech courses are 10 weeks long.  Seven weeks and then we test with three weeks of elmering.  I understand the “fast approach” to licensing, I just don’t agree with it.

To that end, and having a few discussions about life beyond the machine, I introduce six meters.  I understand that this post would mostly be geared towards new hams, but many have not played with this band – and it’s truly neat!

Let me start with what Wikipedia has to say about the band:

The 6-meter band is a portion of the VHF radio spectrum allocated to amateur radio use. Although located in the lower portion of the VHF band, it nonetheless occasionally displays propagation mechanisms characteristic of the HF bands. This normally occurs close to sunspot maximum, when solar activity increases ionization levels in the upper atmosphere. The prevalence of HF characteristics on this VHF band has inspired amateur operators to dub 6 meters the “magic band”.

In the northern hemisphere, six meter activity peaks from May through early August, when regular sporadic E propagation enables long-distance contacts spanning up to 2,500 km for single-hop propagation. Multiple-hop sporadic E propagation allows intercontinental communications at distances of up to 10,000 km. In the southern hemisphere, sporadic E propagation is most common from November through early February.

More on this entry here: http://en.wikipedia.org/wiki/6_meters

That is a good start, but there is so much more to learn.  The one thing I’ve learned most about working six, is propogation.  There are so many propagation methods available, there are even books on the topic (I’ll link to them at the end of this post).  I have a few sites to send your way that demonstrate much of this phenomenon.  Let’s start with The UK Six Meter Group.  Arguably, one of the largest groups dedicated to six meters.  Their website has been updated (though the pagination is really weird in the Mozilla browser) so I’m going to give you two links.  The first has great introduction and propagation information with links to many audio files and a presentation.  This should give you a good start.  The page itself is at http://www.uksmg.org/content/overview.  Trevor has a lot of neat stuff there.  The UK Six Metre group homepage is at http://www.uksmg.org.

Interested in six meter DX?  You might want to look at an article written by Emil Pocock, W3EP.  He wrote a great article for QST a few years back that is available online here:  http://www.ham-radio.com/n6ca/50MHz/6mtrdx.html

Another article written by Dave Finley, N1IRZ is available here:  http://www.qsl.net/n1irz/sixmeter.html

Here is a comprehensive set of links:  http://www.vhfdx.net/six.html

Our friend Randy, K7AGE has done a few neat YouTube videos on the topic.  He may be adding a few more to this series, so check out his YouTube page:

He built a neat rotatable dipole.  This project wouldn’t cost a whole lot of money and get you started:

Interested in six meter contesting and electronic logging?  He made yet another great video:

Thanx Randy!

OK, one more link to an international six meter group, SMIRK:  http://www.smirk.org/

Hopefully, this will get you started on six.

Homebrew six meter amplifier

Filed Under (Amplifiers, Homebrew, Six Meters) by Jonathan on 09-11-2008

I’ve had this site bookmarked for a couple years now, seems too good not to share.

G3WOS six meter, DXpedition solid state amp, packed and ready to go!

This amp is a solid state, 450W beauty that is truly light (I don’t think I’d like to carry around one of them huge solid hollow state jobbies, even though they are nice!).

WARNING!  This is not a first amplifier project.  I’m still building several small QRP amps for a reason – 4,000 volts DC can do a little damage.

Chris set about some design criteria based on several homebrew amps he had used in the past.  This criteria included:

I was determined to have a go designing one with the following key objectives. It needs to:

  • be as light-weight as possible to minimise excess baggage costs.
  • be compact so that it can be transported as aircraft hand-baggage.
    (As it turned out, the final amplifier weighed in at 39lbs compared
    to the 70lb weight of the ACOM 1000!)
  • operate from either a 120 or 240 volt mains supply.
  • be reliable.
  • run up 1,500 watts for possible moon bounce operation subject to local licensing regulations.
  • have full fault protection.
  • be able to take the blower off in transit.
  • be robust to resist damage it it gets dropped.
  • be balanced with the weight distribution centralised so that it can be hand carried.

Lofty planning ideas indeed!

I really like the way Chris laid this site out with all the planning and such (including the cardboard box stages of layout design).  He also includes a plethora of information so that someone can actually take this challenge on, on their own.

Sweet!

Here are a few pics and the link below.  Take your time, plenty of information here!

Top view of the finished project

Bottom view of the finished amplifier

http://www.gare.co.uk/amplifier/

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