We all should know the benefits of salt water and antennas…. but salt water AS the antenna……

Filed Under (Antennas, YouTube Antenna Goodness, YouTube Goodness!) by Jonathan on 15-09-2010

OK, I just had to post this.

I’ve experimented with saltwater when operating portable (one of the benefits of living about a half hour from the shore).  I know friends that have made antennas using salt water, and they had great luck.

This guy, took the idea and spun it on it’s head.  Check out the induction as well – SWEET!

Foxhunt gear – offset attenuators

Filed Under (Antennas, Dayton Hamvention 2010, Homebrew, Kits, VHF/UHF) by Jonathan on 08-07-2010

I attended a great fox hunting presentation at Dayton this year, hence a few posts on the topic.

I had some posts in the past about tape measure beam antennas.  Really neat antennas and they have multiple purpose use (they are GREAT for hitting distant repeaters when you orient them vertically!).  Much like the picture on the right (courtesy of Joe Moell K0OV) they are more useful for fox hunting when you add the active attenuator to your setup.  FYI, Joe is the co-author of the great book “TRANSMITTER HUNTING, Radio Direction Finding Simplified” available where most ham books are sold.  His website has more information on the book at http://www.homingin.com/THRDFSinfo.html and he contributes to CQ and CQ VHF.

So….. just what is an offset attenuator?  Joe explains it on his “Homing in” site as:

An RF attenuator is a device that goes between antenna and receiver to reduce the signal strength down to within the range that the receiver S-meter can handle. Without one, you may think you’re close to the fox when you’re still far away. You won’t be able to get close enough to a camouflaged hidden T to identify it. The amount of attenuation should be adjustable so that you can add just a little when your S-meter first pins, up to a lot as you get within a few feet. Special ARDF receivers used by champion foxhunters have electronic attenuation built in, but ordinary handi-talkies don’t. Adding it would require major micro-surgery in the HT.

His attenuator page is:

http://www.homingin.com/joek0ov/offatten.html

I recommend his site in general, many great projects:

http://www.homingin.com

On his attenuator page, he has full schematics to make an offset attenuator.

But wait…… there’s more!

Further on his page, you see one made in a sweet Pomona box.  I like this box and thought it was a bit pricey at first, until I did the math and figured out the cost/time to do it myself.  These boxes are shielded with the connector of your choosing (BNC/SMA/259, etc).

They generally cost around $25 or so and are shielded!  Great to have.  When you add the cost of connectors and such, it isn’t really so expensive after all.

I really advise using such a case or a metal case in general, makes things work out much smoother in the end.  More information on this box at: http://www.pomonaelectronics.com/index.php?i=prodsub&parent=BOX&cat=BONCONN&getDetails=

But wait….. there’s even more!

Marvin Johnston KE6HTS is now offering a “semi-kit” for this attenuator on his website.  I’ve seen this kit when I was at Dayton this year and encouraged a friend to pick it up and build.  I may end up running a buildathon here in CT on these attenuators.

The price is really not bad at $22.00.  You can purchase them built for a few dollars more.

Information on the kits and pre-built models are at:
http://www.west.net/~marvin/k0ov.htm

And yep……. there’s even more (again!).

If you would like to “roll your own” from parts you may have on your bench, but don’t want to make a circuit board, you can get one from……. you guessed it…… Far circuits.  I picked one up and am going this route myself.

There are a few boards/projects on the Far circuits website at:

http://www.farcircuits.net/

There are a ton of great resources out there on the web, these will really get you going right from the start.  Fox hunting is a really fun and useful part of our hobby and one that doesn’t cost a ton of money to get started in.  If there are no active fox hunts in your area – start ‘em!  There are plenty of options as far as transmitters and such and really doesn’t cost a club much money to get started.

Spud Gun/Antenna Launchers

Filed Under (Antennas) by Jonathan on 08-07-2010

Spud guns or “potato cannon’s” have been around for a long time.  For some reason, I’m shocked that more hams don’t use them for putting up wires.  QST did an article awhile back on the topic getting people started, but not a lot of activity since (at least from what I’ve found online and locally).

The setup on the right here is the CSV19, instructions (and kits available) are on their website at:

http://www.antennalaunchers.com/csv19/csv19asm.html

There is a ton of information on the web.  Unfortunately, a lot of what used to be freely available ended up not being so anymore since people decided to make businesses out of sites that used to give the information away – BAD WEBSITE!  BAD!

Anywhooo……

There is still some other interesting sites with plenty of information.  On that end, I send you to Philip Mayfield.  He has a site with full details on various methods, air displacement, etc. on his site at:

http://www.sigmazone.com/TennisCannon_FullFactorial.htm

I’ve limited this to pneumatic cannons for a reason, the combustible versions are VERY simple.  I just don’t like the mess they leave behind (though they are fun).  Combustion mortars are fun too……. but I digress…..

There is a FANTASTIC video with step by step instructions courtesy of Patrick Norton (of ZDTV fame, then on various shows on the Digg networks).  He did a video on Systm (now canceled program) that is still freely available online – SWEET!

The video below is also available as a downloadable file:

If you want to download the show, or read show notes, visit them at:

http://revision3.com/systm/tennis

If you know of any other resources available online, please post in the comments.

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!

Club Spotlight – RSARS, Royal Signals Amateur Radio Society

Filed Under (Antennas, Club Spotlight, Reference Material) by Jonathan on 28-02-2010

Every now and then, a club does something neat.  The Royal Signals Amateur Radio Society (RSARS) is an interesting club.  Their membership consists of:

Membership of The Royal Signals Amateur Radio Society (RSARS) is open to anyone interested in amateur radio and who has completed service with the Armed Forces of the United Kingdom or certain other countries or is currently serving.

But, for the rest of us, they do have some neat PDF’s of some good antenna projects and useful accessories, including:

THE 40m 4-SQUARE ANTENNA – EA5AVL
A STUDY OF LOUIS VARNEY’S G5RV ANTENNA
CONVERTING THE G5RV for 80m operation
Air Cored 1 : 1 HF BALUN
Antenna Relay Switch – EA5AVL
5-BAND HF VERTICAL – EA5AVL
20m ELEVATED VERTICAL – G8ODE
20m half-wave END FED ANTENNA – Stub matched
20m helically wound MOBILE ANTENNA – EA5AVL
40m quarter-wave VERTICAL END FED ANTENNA – G8ODE
40m EH RECEIVE ANTENNA – G8ODE
160-80-40m END FED ANTENNA – GØCSK
160m ELEVATED FIBREGLASS VERTICAL ANTENNA – G3SZU
160m TOP BAND END FED ANTENNA – G3YEU
160m TOP BAND INVERTED “L” ANTENNA – G8ODE
AIR CORED 1-1 HF BALUN – G8ODE
ALTAI SWR-2T METER CONVERSION
BREMI ANTENNA MATCHER for HF QRP USE
CHOKE-BALUN DESIGNS – G8ODE
80-10m DOUBLET ANTENNA – G3RWF
G5RV MULTI-BAND ANTENNA – U-shaped INSTALLATION – G8ODE
HALF-SIZE G5RV CONVERSION FOR 80m – G8ODE
HALF-SIZE G5RV for a SMALL SPACE – G8ODE
80-10m MULTI-BAND ANTENNA – G8OFZ
REMOTELY OPERATED HF ANTENNA SWITCHES
SAFARI INVERTED “V” ANTENNA – G3RWF
SAFARI ROACH POLE ANTENNA – G3RWF
VERSATILE HF BALUN 1-1 and 4-1 – G8ODE
W3DZZ MULTI-BAND ANTENNA
40m and SHORT 80m ANTENNA
ZETAGI SWR MOD
G3EFYs EMPIRICAL ASYMMETRICAL ANTENNA
160m-6m HF ANTENNA TUNER – G3WME
HF ANTENNA MATCHER – G3WME
HF LOOP ANTENNA TUNER – G3WME
QRP HF ANTENNA MATCH – G3WME
LIMITED SPACE ANTENNA – G7FEK

The clubs direct URL is:

http://www.rsars.org.uk/DEFAULT.HTM

A direct link to the projects downloads are:

http://www.rsars.org.uk/ELIBRARY/docsants.htm

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