Showing posts with label Rotatable Dipole. Show all posts
Showing posts with label Rotatable Dipole. Show all posts

August 29, 2020

Repairing Portable Rotatable Dipole

For portable operations, we have been using a portable rotatable HF dipole from EmComm-Products (model RADS 9-11/A) since 2008.  The antenna provides HF (160m, 80m, 40m, and 20m) and a second VHF/UHF antenna on top of the dipole which is fed by a separate cable enabling concurrent operations of both a HF and VHF/UHF radio on one mast.

Activating Hatteras Island, NC

KC2VSR (Field Day at Fort Ord, CA) rotating the dipole by giving the mast a simple twist

When setting up the antenna for portable operations to teach the radio merit badge in 2018, we discovered that we could no longer tune up when using the 20m elements.  SWR was extremely high.  The was the first time we had an issue when using the antenna after a decade of use.  It was time to give the antenna some attention and bring it back to working order. 


Once back home, we brought out each of the elements and check them individually for continuity using a ohmmeter.  To perm this test, we placed one of the ohmmeter probes on one end of an antenna element and the other problem on the other end of the antenna element.

All the elements passed this basic test with the exception of one of the 20m elements.  The 20m element had no continuity indicating that the wire had a break somewhere along the fiberglass element.

I visually inspected the element for apparent damage and found none.  This suggested that something was amiss with connection between the wire and one or both end connectors.

Corrosion on the joint between the antenna wire and antenna connector

Using an X-acto knife I carefully cut a window in the shrink wrap at the junction between the antenna element wire and the end connector to inspect the connection.  This revealed corrosion on the junction.  Using the continuity tester, I checked for continuity between the wire and both end connections.  This showed continuity at the junction to the far end connector and no continuity to the near connector.  Ah ha!  We found the issue.  The corrosion was likely caused from a decade of operating near saltwater and in the rain.


A brass wire brush was used to remove the corrosion.  The connector was then resoldered to the wire along with a copper wire wrapped all the way around the connector to assure positive contact.  The connector was recovered with shrink wrap and relabelled as a 20m element.  This was a straightforward and easy repair.

Repaired 20m element


We setup a wilderness radio station to teach the radio merit badge at summer camp with the portable rotatable dipole as one of the antennas.

Portable rotatable dipole back on the air at summer camp near Truckee, CA

We setup the antenna with the 20m elements and it performed flawlessly all week while at summer camp.  We made numerous SSB contacts on 20m.

Several people have contacted me asking about buying their own portable rotatable dipole antenna.  Sadly, the manufacturer, EmComm-Products, is no longer in business.  It has been an outstanding antenna.

Good DX and 73,  

August 21, 2020

Radio Scouting: Earning the Radio Merit Badge at Summer Camp

The Radio Merit Badge was earned by 5,205 Scouts in the US in 2018 representing a 10.9% drop from the year prior.  We hams need to make sure we step up our support of scouting and act as counselors for the radio merit badge.  The Radio Merit Badge requirements are demanding and require both classroom learning as well as applied learning in front of a radio.  The radio merit badge looks great on a scout uniform sash with its wonderfully designed Morse code message and lighting bolts.

Scouts BSA Radio Merit Badge

I had the privilege to teach the radio merit badge with my daughter's Scouts BSA troop while at summer camp in the Sierras in Northern California in 2020.  We had a small group of scouts and parents which provided the scouts with more radio operating time and more time for discussion and questions about radio.  This made the merit badge class sessions more fun and engaging.

The scouts had a blast learning hands-on on how to setup the entire wilderness radio station including:
  1. Generator
  2. Power supply
  3. Kenwood TS-480SAT (HF+6m transceiver)
  4. Yeasu FT-8800 (2m / 70 cm FM transceiver)
  5. Kenwood TH-F6A (triband FM HT)
  6. External speaker
  7. 40 Meters home brew wire dipole
  8. 20 Meters rotatable dipole
  9. VHF/UHF antenna
Emergency communication rotatable dipole and VHF/UHF antenna packed up in its storage bag

The scouts made numerous contacts on 40 Meters, 20 Meters, 2 Meters, and 70 Centimeters.  We also tuned up and down on the shortwave broadcast bands and listened in on various programs from around the world.  This was an eye opening experience for the scouts who had never heard shortwave broadcasting nor made amateur radio contacts before.

Kenwood TS-480SAT Transceiver
Kenwood TS-480SAT Transceiver

The rotatable dipole worked like a champ having been serviced in the work prior to camp.  While on the workshop bench before camp, it was discovered that one of the elements had developed a break due to corrosion.  The repair was straightforward requiring a quick cleaning of the corrosion, resoldering, and shrink-wrapping.  The rotatable dipole helped demonstrate the directional nature of dipole antennas to the scouts.

Emergency communications rotatable dipole with VHF/UHF Antenna on top setup at summer camp 

One of our scouts, Sadie, earned her FCC Amateur Radio Technician license (KN6JYE) just prior to arriving in camp.  She had a blast using her license for the first time on VHF/UHF simplex calls, calls over area repeaters, and checking into various area nets including a fun 2m simplex net.  By the way, Sadie and her troop are running a popcorn fundraiser to help keep their scout program going.  Please stop by Sadie's Trails End popcorn storefront to make a purchase and support scouting and her troop.

Sadie, KN6JYE making contacts at elevation 3187m on top of Mount Lassen, California

The scouts were amazed and excited to experience the thrill of DX communication for the first time.  We made contacts on 40 Meters to other states and countries including Hawaii and New Zealand.  DX is alive and well even at the bottom of the solar sunspot cycle.

Amateur Radio Operator scout uniform strip

A big THANK YOU to the patient hams who talked with the scouts and helped them log their very first amateur radio contacts.  These hams helped the scouts to successfully earn their radio merit badges and we couldn't have done it without them.  It is the hands-on learning and radio operations that is the most inspiring and engaging aspect of the radio merit badge.  Several of the scouts expressed their enthusiastic interest in earning their own amateur radio licenses.  Please support scouting, radio merit badge activities, the annual Scout Jamboree on the Air (JOTA) special event, and youth learning the ropes on the air.  The next generation needs our support and encouragement just as much as we all did when we were their age.  Remember, it is youth who are the future of the amateur radio.

Good DX and 73,


August 25, 2018

Radio Merit Badge at Camp Lehi

The Radio Merit Badge is earned by approximately 6,500 Boy Scouts in the US each year.  The Radio Merit Badge requirements are demanding and require both classroom learning as well as applied learning in front of a radio.  I really like the design of the merit badge with its hidden Morse code message and lighting bolts.

Radio Merit Badge
I had an opportunity to teach the radio merit badge at a recent Merit Badge Pow Wow at Camp Lehi here in the Bay Area.  My co-instructor for the course was Ray Wentz, W6LPW.

Camp Lehi is a beautiful location in the Santa Cruz mountains

The night before the course the Merit Badge Pow Wow organizer (Jon) and I installed three antennas: a 40 meters home-brew wire dipole, a 20 meters rotatable dipole, and a vhf/uhf antenna.  We setup the radios and class room in the great outdoors under a couple of canopies.  Power was provide a generator.

Rotatable Dipole and VHF/UHF antenna 

Home brew 40 Meters wire dipole between two trees
The 40 Meters wire dipole worked really well for the scouts.  They made contacts with 100W into the North Carolina to the East, Vancouver to the North, San Diego to the South, and Hawaii to the West.  We were using a Kenwood TS-480SAT.  It was a lot of fun to see the scouts make their first radio contacts ever.

Ray tried several times to call on the local repeater using his HT and found no one to talk to.  Fortunately 40 Meters was in good shape and there plenty of hams for the scouts to talk to.

The rotatable dipole was not functioning properly.  I had brought my antenna analyzer and measured SWR exceeding 3.0.  We didn't have time to determine where the failure was occurring in the system.  That will be a job for another day back at the shack.

A big thank you to the patient hams who talked the scouts and helped them log their first contacts.  This event helped create interest in radio.  Several of the scouts mentioned their interest in studying for their own amateur radio licenses.  Support your local scouting organization and radio merit badge, jamboree on the air, and other outstanding programs.

Good DX and 73,

June 29, 2014

2014 Field Day Fun @ Monterey Bay Amateur Radio Association (N6IJ)

Field Day is FUN!  There is nothing quite like setting up and operating outdoors.

For some hams it is challenge of setting up temporary radio operations in the great outdoors.  For these amateurs, assembling the gear, hoisting and adjusting antennas, solving problems, and making everything work is what it is all about.

Other hams it is about lighting up the ether and operating in the wild.  For these amateurs, the fun is in making great contacts in the great outdoors with perhaps a bit of the old competitive spirit mixed in.

For Field Day 2014, KC2VSR, NJ2X, and KG6UBG set up two outdoor stations at the home of the Monterey Bay Amateur Radio Association (MBARA) headquarters in Marina, California.  We operated using the MBARA call N6IJ.  The site was formerly part of the Fort Ord military base which gave the operations a historical feel.

California weather is famously mild and we were not disappointed during Field Day 2014.  The skies were blue and there was a light cool breeze coming off Monterey Bay that encouraged a sweatshirt or jacket most of the day.  We we felt like we had little too much sun at the end of the day.  We forgot to pack sunscreen; though, we did remember to wear hats.

For antennas, we had a multi-band beam, a wire dipole, and NJ2X's portable rotatable dipole.  The beam was hoisted up onto a pole about about 15 feet and was used with the 20 meters station.  KG6UBG ran the 40 meters station through a ladder line fed wire dipole.  NJ2X and KC2VSR setup the portable rotatable dipole for use with  the 20 meters station.  We rotated the beam and dipole with the aid of ropes attached to the antennas.  A gentle pull on the rope and the antenna could be pointed in any direction.

NJ2X's Portable Rotatable Dipole in the bag

KC2VSR setting up the portable rotatable dipole

K2CVSR with the portable rotatable dipole up and ready for use (California blue sky)

KC2VSR with the 20 meters field day station
KG6UBG running the 40 meters field day station

A few lessons learned for next year:

  1. Pack sunscreen - our wide brimmed hats alone didn't keep us from getting a little too much sunshine
  2. Pack more snacks - we lost a bit of operating time making a mid-day food run
  3. Encourage a few more folks to come out and play radio - the more the merrier
  4. Fire up the grill - hot dogs and hamburgers would be terrific next year
  1. Failing to inspect the antenna bag beforehand to make sure technical info and everything needed is inside - we discovered that we had not packed a manual needed to setup the antenna.  Through trial and error we figured out how to put up the mast and tune the antenna for 20 meters; though, at the expense of operating time.
  1. Bringing KG6UBG's Honda generator - small, quite, and ran flawlessly during the day providing power to our amateur radio stations
  2. Bringing the rotatable dipole - setting up a temporary antenna is part of the field day experience
  3. Setting up field day operations at the Monterey Bay Amateur Radio Association HQ - great location with plenty of room for operations, grilling, antennas, ...
  4. Drinking plenty of water - hydration is extra important when outdoors in the sun and breeze
  5. Pack a few spare batteries - 9v, AA's, ... handy when needed as proven by KG6UBG having a spare needed for our 20 meters station's SWR meter.
  6. Bringing 2 meters HT's - handy for communications around the field day site

2014 is 100th anniversary of the ARRL so this year's field day was particularly important for many amateurs.  It was a memorable event for KC2VSR and NJ2X since it was our first in the great state of California and with the Monterey Bay Amateur Radio Association.  We enjoyed it thoroughly and look forward to next year.

A special "thank you" to KG6UBG for helping pull together this year's field day.  It simply would not have happened without him.

Good DX and 73, NJ2X

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© Michael W. Maher and NJ2X.COM, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael W. Maher and NJ2X.COM with appropriate and specific direction to the original content.

December 10, 2011

Portable Rotatable Dipole

For our portable operations, we have been using a portable rotatable HF dipole from EmComm-Products (model RADS 9-11/A) since 2008.  This antenna is rated for up to 200W UHF/VHF / 250W PEP HF.  In our setup we run no more than 50W on UHF/VHF and 100W on HF.

One particularly useful feature of the antenna is that it provides HF and a second VHF/UHF antenna on top of the dipole which is fed by a separate cable.  This allows the operator to run both a HF radio and VHF/UHF radio concurrently on one mast.

The mast is sectional fiberglass, guyed, and goes up very easily with two people (takes about 15 minutes).  The Velcro cable ties used to neatly store the cable double as ties between the mast and cable.

To rotate the antenna we simply give the mast a twist.  This is usually enough to cause the dipole to turn in the in the desired direction.  We have also used a light line tied to one end of the dipole to guide the rotation.
Dipole that can be rotated manually
NJ2X's Rotatable HF Dipole Antenna on the beach in Hattaras Island, NC

The dipole sections can be changed out and manually "tuned" for all HF bands from 160m to 10m and also VHF on 6m.  Tuning is accomplished by adjusting the telescopic sections.  A roll up tape measure and guidebook in the bag helps with the adjustment for specific bands and frequencies.

The entire antenna system packs up neatly into a heavy duty military green water resistant bag.  This makes it our preferred field day antenna.  We have also used it for mini-DX expeditions.  Pictured above is the antenna setup overlooking the beach on Hatteras Island, NC.

Emergency communication rotatable dipole antenna packed up in its go-bag

This antenna system has been a real pleasure to use and we look forward to breaking it out again for Field Day 2012.  Now only to decide where we will take it...



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© Michael W. Maher and NJ2X.COM, 2012. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael W. Maher and NJ2X.COM with appropriate and specific direction to the original content.