A Multi-Band 33 Foot Dipole


See on Scoop.itKH6JRM’s Amateur Radio Blog

eHam.net Article: A Multi-Band 33 Foot Dipole – Work 20m, 17m, 15m, 12m, and 10m without an antenna tuner!
– eHam.net is a Web site dedicated to ham radio (amateur radio).

Russ Roberts‘s insight:

A fascinating antenna article from the always inventive Cecil Moore (W5DXP).  The key to his "multi-band 33 foot dipole" is a sophisticated switching and relay system that automatically adds or subtracts various lengths of 450 ohm ladder line without the use of a tuner.  By  switching in various lengths of feed line, he can "tune’ each band without resorting to a manual or automatic antenna "tuner".  If you’re mechanically inclined and have some time over the weekend, you may want to build his antenna system.  Apparently, Cecil has had excellent results from this "tuner-less" antenna.  Aloha de Russ )KH6JRM).

See on www.eham.net

5 tips to keep your three-phase UPS healthy year-round


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5 tips to keep your three-phase UPS healthy year-round

Russ Roberts‘s insight:

A quick, informative slide presentation by "eaton.com" on keeping your computer UPS alive and well.  Good, basic information.  Aloha de Russ (KH6JRM).

See on powerquality.eaton.com

EEVblog #584 – What Effect Does Your Multimeter Input Impedance Have? – YouTube


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What effect does your multimeter input impedance have on the circuit you are measuring? Dave shows a practical example of how it can really screw things up i…

Russ Roberts‘s insight:

Here’s the "dark side" of multimeter operation.  Excellent video with some useful operating suggestions.  Aloha de Russ (KH6JRM).

See on www.youtube.com

This Week in Radio History


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Feb 24, 1942 VOA begins operations from New York City. Feb 26, 1934 President F.D. Roosevelt urges Congress to create the Federal Communications Commission. Mar 1, 1949 First 45 rpm record issued by RCA: Texarkana Baby by Eddy Arnold. Mar 1, 1972 Intel introduces 8008 processor. Mar 2, 1897 Marconi granted first wireless patent

Russ Roberts‘s insight:

Another fascinating "This Week in Radio History" from reporter David Hall.  The only things I remember from this interesting list are the introduction of the first 45-rpm record ( I was a young lad then) and the introduction of the Intel 8008 processor.  Time flies when you’re having fun.  Aloha de Russ (KH6JRM).

Successful launch of ham radio satellites | Southgate Amateur Radio News


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On Thursday, February 27 at 1837 UT a cluster of Japanese amateur radio satellites were launched from the Yoshinobu Launch Complex at the Tanegashima Space Center (RT @SAR_News: Successful launch of ham radio satellites | Southgate Amateur Radio News…

Russ Roberts‘s insight:

The Tanegashima Space Center in Japan has confirmed the successful launch of several amateur radio satellites.  There have been at least two reports of good signals from the micro-satellites.  The student team that developed and built the ITF-1 CubeSats would appreciate any reports of their satellites on 437.525 MHz FM Morse Code.  Aloha de Russ (KH6JRM).

See on www.southgatearc.org

ARNewsline Report 1907 — Feb 28 2014: – eHam.net


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ARNewsline Report 1907 — Feb 28 2014:
eHam.net
An Ohio town is appealing the States PRB-1 like law into the court system. This after it lost an appeal by a ham who was given the right to put up an antenna that the municipality had denied.

Russ Roberts‘s insight:

Here’s the latest "ARNewsline Report", highlighting the struggle of an Ohio ham trying to erect an antenna on his property.  Although he got permission to build a tower, neighbors opposed to the structure have appealed Ohio’s PRB-1 like law to the legal system.  The ARRL is offering legal advice to this amateur radio operator.  The NIMBY (not in my backyard) syndrome is alive and well.  It’s time to go "stealth mode."  Aloha de Russ (KH6JRM).

See on www.eham.net

Birmingham Amateur Radio Club hosts BirmingHAMfest 2014 – Alabama’s13.com


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Birmingham Amateur Radio Club hosts BirmingHAMfest 2014
Alabama’s13.com
Ham radio enthusiasts will flock to the annual BirmingHAMfest is this weekend, hosted by the Birmingham Amateur Radio Club.

Russ Roberts‘s insight:

If you’re in the Birmingham, Alabama area this weekend, be sure to visit the "BirmingHam Fest" Saturday and Sunday at the Zamora Shrine Temple in Birmingham.  Doors open each day at 0900 local time.  Aloha de Russ (KH6JRM).

See on www.alabamas13.com

State police announce partnership with amateur radio group – Cape Gazette


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delaware state police and the sussex county amateur radio emergency service have established a relationship whereby ares will provide emergency back-up communications for the state police.
this …

Russ Roberts‘s insight:

Formal agreements such as this Delaware partnership between law enforcement and the amateur radio community are "win-win" situations for all concerned–police, hams, and local communities.  These memoranda of understanding (MOI) further solidify amateur radio’s commitment to emergency communications, public service, and community preparedness.  Aloha de Russ (KH6JRM).

See on capegazette.villagesoup.com

Low-cost, battery-free gesture recognition technology for all devices


See on Scoop.itKH6JRM’s Amateur Radio Blog

 Mute the song playing on your smartphone in your pocket by flicking your index finger in the air, or pause your “This American Life” podcast with a small wave of the hand. This kind of gesture control for electronics could soon become an alternative to touch screens and sensing technologies that consume a lot of power and only work when users can see their smartphones and tablets.

University of Washington computer scientists have built a low-cost gesture recognition system that runs without batteries and lets users control their electronic devices hidden from sight with simple hand movements. The prototype, called “AllSee,” uses existing TV signals as both a power source and the means for detecting a user’s gesture command.

 

“This is the first gesture recognition system that can be implemented for less than a dollar and doesn’t require a battery,” said Shyam Gollakota, a UW assistant professor of computer science and engineering. “You can leverage TV signals both as a source of power and as a source of gesture recognition.”

 

The technology is set to appear April 2-4, 2014 at the Symposium on Networked Systems Design and Implementation conference in Seattle.

The researchers built a small sensor that can be placed on an electronic device such as a smartphone. The sensor uses an ultra-low-power receiver to extract and classify gesture information from wireless transmissions around us. When a person gestures with the hand, it changes the amplitude of the wireless signals in the air. The AllSee sensors then recognize unique amplitude changes created by specific gestures.

Russ Roberts‘s insight:

Gesture Recognition Technology is coming to an electronic device near you.  Scientists at the University of Washington have developed "AllSee", a type of gesture control for electronics which "could become an alternative to touch screens and sensory technology that consume a lot of power."  The "AllSee" prototype doesn’t require batteries and allows users of cell phones, iPods, televisions, and tablets to control  their devices "with simple hand movements."  There could be some applications to amateur radio, such as tuning a transceiver, adjusting a "tuner", and even rotating a beam on a tower.  Interesting possibilities lie ahead.  Aloha de Russ (KH6JRM).

See on www.washington.edu

Simple Ham Radio Antennas: An 80-10 meter inverted vee dipole. Post #263


A few days ago I read a fascinating antenna article by Cecil Moore (W5DXP) on the http://www.eham.net website.  Cecil described what he called a “Multi-Band 33-ft dipole” that works on 20, 17, 15, and 10 meters without an antenna “tuner” (i.e. transmatch).  The secret to this outstanding antenna was the use of 450 ohm ladder line in conjunction with a series of switches and relays that selected the proper length of ladder line used to feed the antenna.  Depending on the band of use, Cecil could insert and remove sections of ladder line with his relay/switch system so that swr across his chosen band remained low.  By carefully selecting which section of feed line to add or subtract, he got a decent performing antenna without having to resort to a transmatch or “tuner.”

Cecil’s idea got me thinking of ways to improve the dipoles I’m using at my new home site.  Although his idea has a lot of merit, I felt the need to build something a bit simpler that would get similar results.  My requirements were simple:

The antenna would require one tall support.  I didn’t want to climb trees to erect an antenna.  At my age, a fall really can ruin your day.

The antenna had to cover Hawaii Afternoon Net frequencies, 3.888 MHz and 7.088 MHz.  I would also like to work some DX on 20 through 10 meters.  So, the antenna would have to cover 80 through 10 meters.

Although I had erected a basic doublet in December 2013, it had fallen victim to a winter storm and high winds.  I needed a replacement for this general coverage antenna.

The 40-meter loop had been removed to make way for a family garden in the back yard.  My xyl and I are trying to become more food self-sufficient.

So, I decided to re-invent my first novice class antenna–the 80 to 10 meter inverted vee.  As I remember, the antenna was cheap, only took one tall support, and could cover several amateur radio bands with the use of an antenna transmatch, a 4:1 current balun, some surplus speaker wire, and a length of 450 ohm ladder line.  Most of the materials were stored in the new garage along with ceramic insulators, a “ladder lock” center connector, some wooden support stakes, various lengths of RG-8X coax with UHF connectors, and some spare tools.

The construction would be straight forward, with most of the building done on the ground and the antenna later raised into position on a fiberglass mast.  The inverted vee is a simple antenna, which is nothing more than a drooping 1/2 wave dipole cut for your lowest operating frequency and fed with ladder or open wire line to a balanced “tuner” capable of accepting such a line.  In the absence of a balanced “tuner”, you can connect the ladder line to a 4:1 current balun and use a short length of 50 ohm coaxial cable to connect the antenna system to your transmatch or “tuner.”

CONSTRUCTION PHASE:

Using the general dipole formula 468/f (MHz)=L (ft) and the lowest design frequency of 3.500 MHz, I came up with a total dipole length of 137.71 ft/40.76 meters.  Each sloping dipole element would measure 68.85 ft (around 68 ft, 10 in.)/20.38 meters.  The only wire available last weekend for the project was about 150 ft/45.73 meters of #18 AWG speaker wire from Radio Shack.  For most of my antennas, I try to use stronger wire, such as #14 AWG household wire.  But in this case, the speaker wire was all I had.

I attached a ceramic insulator to one end of each antenna element.

I had a spare 33 ft/10.06 meters  MFJ telescoping fiberglass mast in the garage that would serve as the support for the inverted vee.  I extended the mast to its full length and proceeded to attach the 450 ohm ladder line to the mast.  I would be using 90 ft/27.43 meters of ladder line, because the antenna would be erected at one end of the garden which was approximately 65 ft/19.81 meters from the radio room in the garage.  I attached a “ladder lock” device to one end of the ladder line, looped a piece of nylon rope through the top support hole, and tied the “ladder lock” to the tip of the mast.

I ran the ladder line down from the top of the 33 ft/10.06 meter mast to a point about 8 ft/2.43 meters above the bottom of the mast.  The ladder line was secured to the mast by nylon ties.

Each antenna element was soldered to a leg of the ladder line.  Connections were wrapped with several layers of vinyl electrical tape.

With construction complete, I drove a 5 ft/1.52 meter wooden support stake into the ground to support the fiberglass mast.

I then hoisted the mast into position, tied off each antenna element to nearby trees with nylon rope, and adjusted the antenna to a uniform shape.  The ends of each element were approximately 10 ft/3.04 meters above ground level.

I then pounded six, five-ft/1.52 wooden stakes into the ground, each 10 ft/3.04 meters apart, to support the ladder line off the ground until the ladder line reached the window of the shack, some 65 ft/19.81 meters from the base of the mast.

I slipped the ladder line through the bottom of the shack window and connected it to a W9INN 4:1 current balun.  A three-ft/0.91 meters length of RG-8X coax with UHF connectors mated the antenna with the Drake MN-4 transmatch (“tuner”).  Short pieces of RG-8X connected the Ten-Tec Argosy II with the Drake MN-4, a low pass filter, and a Heathkit Dummy Load.  If I want to use 30 meters, I substitute a MFJ-941E Versa Tuner II for the Drake MN-4.  The Drake “tuner” doesn’t cover 30 meters.  As a final step, I attached a 68-ft/20.73 meters “counterpoise” to the ground lug of the antenna transmatch.  The “counterpoise” is in addition to the regular station ground which uses a short length of copper braid clipped  to an 8-ft/2.43 meters copper ground rod.

INITIAL RESULTS:

With the Drake MN-4 or MFJ-941E in the line, I can get a swr of 1.1 to 1 on all bands from 80 to 10 meters.  Unlike other multi-band designs, this antenna requires an antenna transmatch or “tuner” to work properly.  Because of its relatively low height, the inverted vee works very well as a NVIS (near vertical incident skywave) antenna on 80 and 40 meters.  This antenna provides excellent local and state wide coverage throughout the Hawaiian Islands.  DX begins to pick up at 20 meters, where the apex of the antenna is nearly 1/2 wavelength above ground.  When 15 and 10 meters are open, I get good signal reports on both cw and ssb.

The inverted vee gives me satisfactory performance at a cheap price.  It’s easy to build, requires no ground radial system, and can be used in portable or emergency situations.  Most of the materials for this simple, effective antenna can be found at the nearest hardware store or home improvement outlet.  Some of the accessories, such as insulators and center supports can be “homebrewed” with plastic, teflon, or even plexiglass.

REFERENCES:

http://www.hamuniverse.com/hfdoublet.html.

http://www.w4rnl.net.46/abd.html.

http://www.designerweb.net/downloads/DoubletAntenna_80-10m.pdf.

http://www.theladderline.com/doublets-ladder-line-and-automatic-remote-tuners.

http://www.eham.net/articles/31603.  This is the outstanding antenna article by Cecil Moore (W5DXP).

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Aloha es 73 de Russ (KH6JRM)

BK29jx15–along the beautiful Hamakua Coast of Hawaii Island.

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