David's Narrow Copper J-Pole Antenna

This is another post from one of our members!  David sent me a bit of this in an email and I thought it would be great to share with the group!  If you would like to post something here about your projects, experience or thoughts, let me know and we will see if we can post it up!

Narrow Copper J-Pole Antenna
Written by David Keath – N0WKZ

The goals I had in mind for this antenna were relatively simple.  Specifically the low takeoff angle of the Slim-Jim mixed with some of the durability characteristics of the larger cactus copper J-Pole.  Another desirable feature I was seeking that the Slim-Jim does not tend to have due to it's small conductor size is a wider usable bandwidth.  The final result is not a magic bullet, nor does it exhibit miracle performance.  Within reason, it does seem to have the qualities I was trying to achieve.

The dimensions and materials I am listing here come directly from the antenna, which is currently in use at the time of this writing.  I tuned and tested this version using nothing more than the built in VSWR meter on my radio.  Like any other antenna device, this antenna was tuned to my own equipment in my operating environment.  Please be mindful that the J-Pole design is generally somewhat sensitive to environment. Cutting and tuning it on different equipment in a given location may alter the final tuned dimensions slightly. Please also remember that this project was and is an experiment.

Materials Used
• ¼ Inch Diameter Soft Copper Tubing – at least 6.7 Feet
• Common Black Electric Tape
• Small Diameter Nut, Bolt, Washer – 2 Sets
• 1 Card Board Toilet Paper Tube
• Fishing Line – Enough to make a loop for hanging the antenna

Tools Used
• Ordinary Pliers
• Screwdrivers – Phillips and Flathead
• Utility Knife
• Scissors
• Cordless Drill and 7/64 or 1/8 inch Bit

Measurements Approximate
• Long section of the J – 60 inches.
• Short section of the J – 21 inches.
• Bottom section of the J – 0.5 inches.
• Feed-point location from the bottom of the J – 2 inches.

The total length here is long for construction purposes.  It should initially be approximately 81.5 inches/6.7 feet.

NOTE: If you feel confident in working with the copper tubing, you can use lengths closer to the final dimensions which are listed below for reference.  I would however recommend leaving at least an extra 2 inches on the long element and perhaps an extra inch on the shorter one.

Final Tuned Dimensions – Approximate
• Long section of the J – 54.5 inches.
• Short section of the J – 18.75 inches.
• Bottom section of the J – 0.5 inches.
• Feed-point location from the bottom of the J – 2 inches.

Construction
Measure the tubing  and mark off the points where the two bends making the bottom of the J should be located.  Be careful to leave the extra length of tubing on each element before making the bend.

Pliers may be used to flatten the  bottom section of the J.  Being careful to work slowly and carefully, bend the tubing into the J shape.  Used gently, the Pliers can aid in this process.  The average gap or space between the J elements should be approximately 0.5 inches.  This gap is between the tube surfaces, not center to center.

Cut small rectangular strips from the toilet paper tube.  Use a number of them together to create a simple spacer between the elements.  I used electric tape to hold them together and in place.

The area of the feed-point should be flattened and drilled.  Use the feed-point location listed here.  There is no need for the extra holes.  Feed-point holes should be located 2 inches from the bottom of the J.

Choke Balun
5 Turns at about 5 Inches Diameter of RG-58

Handling
While this device is certainly more durable than a Slim-Jim, soft copper tubing can be warped or bent.  Too much rough handling or a good hard drop could damage it.  Some care should be exercised in handling the device.

Mounting
I intended this device for indoor use, either ceiling hung, or installed in an attic.  The main idea is to keep the antenna as far from nearby dense objects or metals as possible, choke the feed-line, and isolate it from direct contact with conductive surfaces within reason.

Feed-Point Polarity
Depending on what publication you read, there seems to be a difference of opinion about which element on the antenna the coax center conductor should be attached too.  Based on most articles I have read, I chose to attach the coax center conductor to the long element on the antenna.  Supposedly this is the difference between having a lower verses a higher takeoff angle.

Tuning
Coax with the choke formed at the antenna end should be attached to the antenna feed-point allowing most of the choke to hang off below and too the side of the antenna within reason.

NOTE:  Before going any further, please remember that trimming off too much Copper cannot be undone.  Certainly an extension can be added but that defeats the whole simplicity idea.  Take your time trimming and tuning the antenna.

• The short element of the J should initially be just slightly longer than my final tuned length.

• The long element of the J should initially be longer by an inch or more.

• The antenna should be initially placed or hung in it's desired location or someplace similar and then check the VSWR at the top, middle, and bottom of the 2 meter band.

• Most of the tuning should achievable by trimming the long element until VSWR is low across the entire 2 meter band.  I would be careful trimming  too much off the short element.

• Trimming is done by grasping the Copper near the top of the long element and using pliers to flatten 1/8 to ¼ inch of copper.  Carefully work the flat copper back and forth with the pliers until it breaks off.

• Check the VSWR between each trim.

• The antenna should initially have a lower VSWR value near the bottom of the band.  Shortening the long element by small amounts and re-checking the VSWR should move the low VSWR region up until eventually the VSWR is acceptable across the band.  That is where I stopped trimming.

When tuning is complete, a small section of copper at the top of the long element can be flattened and formed into a small hook or drilled for a fishing line loop to hang it.  Be certain to hang it securely.

NOTE:  Because I do not own a device to analyze the antenna, it may have positive or negative characteristics I am unaware of.  I would be grateful to anyone who builds the device and tests it with an analyzer to send or share the results.  pu239u235@gmail.com

References:
NOTE: There are more web sites about J-Pole antenna devices and designs than I can list here.  These sites I have listed lead to many others and provide useful information.  Simply searching the word jpole on the Internet will also yield many other sources of information.

Jpoles - Mythbusting and the perils of rogue RF currents. By John Huggins, KX4O
https://docs.google.com/presentation/d/1uJ_INHlJEXUFeDrEiBgRcpQRKZ3TNSx6ahN_lWdX4ms/edit?pli=1#slide=id.p14

JPOLES Handbook, 4th Edition Buck Rogers, K4ABT
http://www.buxcomm.com/jpoles4ever.htm

Web Station, N9TAX
http://www.n9tax.com/Slim%20Jim%20Info.html

I wish to thank the SEKARC Club, Pittsburg KS, USA  for allowing me to submit this project so that others may perhaps use and even improve it.  If errors, comments, improvements, or anything else regarding this antenna comes to light, please do submit that information in the comments below so that others might benefit.

The J antenna design has been around since the time of the rigid airships prior to WWII.  The Slim Jim has also likely been around for some time.  Neither design is my own.  As well, it is unlikely that I am the only operator to attempt to make a rigid narrow J pole.  In essence, I can only state that I constructed this project as an experiment based on existing sound designs.  This is what Amateur Radio is all about.  Experimentation, improvement, and a sharing of those experiences with others.  Of course, there is always the inevitable failures on the way to successes but that is the way of it...

73's
Sincerely, D Keath – N0WKZ – 2013

Element Closeup

Balun Coil

Feed point Closeup

Complete

Hanging Method

Great Meeting

We had a great meeting Saturday! Eight local hams attended and a wide variety of topics were discussed. From flying broken airplanes, hamcan issues, Baofeng $38 specials, to listening to the Gorillas game on an unexpected HF band.  If anyone wants to add anything about the meeting, please do so! Just click the comments button below. It would be fun to see Bill's explanation of the HF Gorilla game!

  

The Baofeng UV-5RE Plus that I recently purchased was a good topic. The $38 price is convenient. It works well, especially if you can get the software to use for programming ( I recommend Chirp and not the Baofeng software ). The scan is a little slow but I just skipped more channels and changed a setting and it works great. I might do a little review for our readers for those unfamiliar with these radios. The funniest item was discussing the translations in the manual and on the equipment. Justin had a picture of instructions on a similar Chinese radio that is very funny. He sent the photo to me so we could share it with everyone. Thanks Justin !

Thanks for all that attended. These meetings are becoming more enjoyable and more informative as we all get to know each other better. With the collection of experienced hams that attend, their stories are the best. If you have been thinking about it, please make a point to come to the next one on November 30th.

  

On The Lighter Side...

And now for an oldie from across the pond. Here is a funny take on Ham Radio! The 1960 BBC TV comedy series 'Hancock's Half Hour' starring Tony Hancock - and in particular, the infamous bungling radio ham segment.

Enjoy...

Joe's QRP Station Build

This is the first member post of many I hope. Joe wrote this piece about a recent project. If you would like to post something here about your projects, experience or thoughts, let me know and we will see if we can post it up!

Joe's QRP Station Build
by Joe Porter WØMQY

I'm a big fan of portable qrp operations and enjoy the PSK31 mode.  There are always lots of cables and boxes to carry around with you, and I decided there must be a better way.  The following photos show my solution to keeping it all together.

I removed the printer stand from my computer lab because it was too large and took up too much desk space.   I can’t claim originality for the idea but after stumbling over the stand for several months, I assembled it into a portable QRP_PSK31 unit.  Under the stand on the left is the Icom 703®, in the center is the Signal One® PSK31 interface, and on the right is the external speaker.  Handles were placed on the top of the stand for ease of carrying.  The top of the stand makes a nice resting place for the laptop.  The two heavy steel legs make it a great support for the computer but raises the keyboard above the level I like to type.  This problem was solved by using a small collapsible table that has a height adjustment.  This table is set to about 24” high bringing the laptop to a comfortable typing position.

While this particular setup would not satisfy the biker, pedestrian, or back pack mobile enthusiast, it does simplify my setup and teardown time in the local park.  This package was used the past weekend with great success during the Brutus Bash in my camping trailer.   For a quick stint in the local park, it is a keeper.

 

This photo gives a better view close up of the operation position.  The stand seemed to slide around on slick surfaces so a couple of heavy chair grommets were added to the bottom of the legs to provide stability.

 

This photo shows the arrangement of the equipment underneath the stand.  The Icom 703® is on the left, the Signal One interface® with associated cabling in the center, and the Icom 703® external speaker is on the right. Directly behind the above equipment are two 7 amp hour SLA batteries.  One battery is used for operation while the other is on the charging system.

 

A 15 watt solar panel provides the charging power for the second battery while the radio is operated from the first battery.  The panel is probably marginal in keeping up with the radio but it does a nice job of charging the second battery in the pack.  So far, the batteries have outlasted me on my trips to the field.  That put my fears to rest on whether I had enough battery power for a weekend or a 4 hour sprint.

The Icom 703® would not be the radio of choice if I were going for a long haul because it draws 350 ma. on receive and the transmitter will pull about 1.5 amps on transmit.  Although these two batteries with the solar charging system make it completely portable it does have limitations with its size and weight.  For me, that is offset by the quick setup and tear down time.  Coupled with some South Bend® SD20 collapsible fishing poles and a dipole for each band, it makes the ideal portable companion for me.  The beautiful part of all this is that the Icom 703 gives me CW, PKS31, SSB, RTTY, and NDB chasing.   The complete portability of this system provides many an opportunity to go to the park, woods, Brutus Bashes, or any other event I might want to operate.  It also has the neat feature of being a quick setup in time of disaster for a small command station to assist in public service.

Last but not least, it was decided to keep things as simple as possible to minimize breakdowns, broken cables, and solder joints in the field.  As is shown in the photo, all of the equipment including the batteries are equipped with Anderson Power Pole® connectors.  This makes for easy switching batteries, removing equipment for other projects, and just plain versatility.

 

This project has given me pleasure both assembling and using it.  I love QRP radio and portability. This package gives me both.  If you haven’t tried portable operation, I suggest you give it a try.  It is great fun and you get to enjoy the great outdoors.

72/73’s   Joe  WØMQY

To Honor KAØEGE Charles Chancey

Now on a personal note... I am honored to now have the call sign KAØEGE, originally granted to my father Charles Chancey. By example, he taught me patience, hard work, honesty, honor, humor and love. I will transmit with this call in memory of him. Below is his QSL card which incorporated the logo from Harry's Cafe which our family started, worked for and owned spanning 3 generations. I am working on a new version of Radio Harry for my QSL card.

I remember his ham shack with Heathkit radios, big brown plastic rotor controller, CW key, KAØEGE sign over the door, QSL cards from all over the world, and the ham shack was wallpapered with National Geographic maps pasted to the wall. He worked very hard at the hobby and was awarded the WAS, WAC and the DX Century Club award.

My brother in law John Penrose WBØUFV who is on our club roster played an instrumental role in dad's ham radio time. Back when the Pittsburg repeater was way up on the KOAM tv tower they could have qso's between here and Springfield. Dad was also the treasurer of the Pittsburg Repeater Organization and after I got my ticket, John gave me a KAØEGE decorated mug from dad and a metal box he held from the club with handwritten note cards with members call sign, address and due payment history. I bet there are some names in there many of you would recognize and possibly some of you ARE in there.

Below I have posted some photos from his Field Day in the yard with WBØUFV a newspaper article from the newspaper, to his certificates and awards. If you knew him or have memories of dad, feel free to post them in the comments below!

Thanks everyone !! 73's KAØEGE clear.