Showing posts with label Antenna. Show all posts
Showing posts with label Antenna. Show all posts

February 7, 2021

40m Skywire Loop Antenna Experiment

I have been curious about skywire antennas since becoming a ham.  I first learned about skywire antennas initially from a contacts made with hams operating on skywire loop antennas.  Over the years I have received many recommendations to give one a try.

I decided it was high time to build my own homebrew skywire loop antenna with the goal of constructing it from various pieces-parts available in the shack.  There is simply no better way to spend a Sunday than making something in the workshop with the HF transceiver running.

A full wavelength skyloop antenna has a nominal impedance of 120 ohms depending on various factors.  The ideal antenna impedance is 50 ohms which would match a 50 ohm coaxial cable and 50 ohm transceiver.  A skywire antenna would work more efficiently with a 2.5-to-1 balun to transform the antenna impedance to more closely match the 50-ohm coaxial cable.  

A balun is an electrical device that converts between a balanced signal and an unbalanced signal. There are many different types of baluns including those that transform impedances.

Unfortunately, I didn't have a 2-to-1 or 2.5-to-1 balun in the workshop.  I did have a 1-to-1 balun and a box of type-43 ferrite beads.  I decided using a 1-to-1 balun and ferrites would be close enough and help keep common mode currents off my coaxial cable.  I also had an unused coaxial antenna center conductor, a spool of wire, and a few insulators.  These were enough parts to give the 40m skyloop a ago!

A skywire loop antenna is exactly as it sounds a single wire in the shape of a circle (ideally) some other shape such as a square, rectangle, or triangle and suspended horizontally.  To calculate resonance of #18 wire, the following formula can be used:

Length in feet = 1005 / frequency in MHz

For example, at the FT8 40m calling frequency a resonant skywire = 142 ft. = 1005 / 7.074 Mhz

Skywire Loop Antenna Bill of Materials
  • 136 ft of Poly-STEALTH 18 gauge wire from Davis RF
  • qty 11 type-43 ferrite beads 1/2" snap on
  • CE-1 Deluxe Dipole Antenna Center Feed from Spi-Ro Manufacturing
  • 1-to-1 Balun Designs Maxi Choke Balun (5kW) dual core model 1115du
  • qty 3 "dog-bone" type insulators
  • Self-sealing silicon tape
  • 3M electrical tape
  • Stuff - dielectric water proofing filler for coaxial connectors

CE-1 Deluxe Dipole Antenna Center Feed

1-to-1 balun connected with LMR400 with ferrites connected to the antenna center feed 

I used trees to support my skywire loop antenna.  Two of the corners were up around 40ft and the other two were on the low side at around 20 ft.  Not ideal but good enough to tune up and work some DX.  I used floating insulators when hanging the antenna.  Floating insulators allows free movement of the insulators and antenna wire while adjusting the antenna.  It allows provides freedom of movement due to tree sway.

The goal in hanging a skywire loop antenna is to maximize the enclosed area of the antenna.  Given infinite hangers, a circle would yield the maximum enclosed area.  Fortunately, the skywire doesn't require perfection.  A rectangle with four hanging points works very well too.

The Poly-STEALTH antenna wire from Davis RF is wonderful to work with - strong, light, and nearly invisible.  136 ft. of #18 wire weighed only 0.136 lbs. which is much less than my multiband fan dipole.  The insulators and rope weighed more than the entire antenna.

Initial Results

I was delighted to find that I my Kenwood TS-480SAT's build-in antenna tuner would tune the skywire on 40m, 20m, 17m, 15m, 10m, and 6m effortlessly.  This is a great way to begin testing a new antenna - no tuning or trimming.  Next I fired up FT8 and worked 20m and 40m contacts as the grey-line passed on into the evening.  The signal-to-noise ratio seemed improved as compared to my fan-dipole antenna.  I quickly made contacts with stations near and far including:
  • 40m KN4APP, NV - 203 miles
  • 40m AB6ZQ, CA  387 miles
  • 40m KE7JBK, AZ - 597 miles
  • 40m N7DBO, UT - 600 miles
  • 40m KF7UGG, OR - 618 miles
  • 40m K7EAZ, AZ - 694 miles
  • 40m KS7TU, WA - 792 miles
  • 40m KG5ZZB, TX - 1460 miles
  • 20m KB0BRO, MN - 1565 miles
  • 20m W9RF, IL - 1797 miles
  • 20m KH6AN, HI - 2353 miles
  • 40m N3MK, VA - 2527 miles
  • 20m JA9DJX, Japan - 5286 miles
  • 20m LU8DN, Argentina - 6597 miles
  • 20m ZL1IA, New Zealand - 6732 miles
The 40m Skywire experimental antenna was a huge success.  The antenna worked perfectly the first time I tuned it up.  It is remarkable how flexible the antenna is using just a build-in antenna tuner.  No adjustment or fine tuning was required to get on the air on multiple bands.  It also performed very well at the bottom of the sunspot cycle.  Overall, I am pleased with the outcome and would recommend a skywire loop antenna to anyone with suitable supports, a few inexpensive parts, and a Sunday to experiment.  It is a surprisingly good antenna for very little cost.

I am looking forward to trying out the new skywire antenna on 17m, 15m, 10m, and 6m when the bands are open.  I am also looking forward to a future experiment with an 80m skywire loop antenna.


Good DX and 73, NJ2X

September 18, 2020

Transmitting using a vintage Radio Shack center-loaded telescoping antenna

I have a vintage Radio Shack center-loaded telescoping antenna from the early 1990's.  It has a BNC connector and a loading coil in the middle of the telescoping sections.  It ordinarily sits in a box along with other radio odds and ends that I don't use regularly.  Radio Shack made these for ages and you can still find them for sale online.


Radio Shack center-loaded telescoping antenna with all sections collapsed


I was recently working on a vintage Kenwood TH-22AT 2m HT that still has its original rubber duck antenna.  The antenna wasn't pulling-in stations very well so I decided to dig out my old Radio Shack telescoping antenna and give it a try.  I was happy to find that the Radio Shack antenna worked better than the stock rubber duck.

As I was setting it up, I remembered that some adjustment is required in order to use it for transmitting.  The antenna can be used on a transceiver or a receiver such as a scanner.

Receiving: 25 MHz through 1296 MHz
Transmitting: Can be used as a 1/4 wavelength transmitting antenna from 130 MHz through 535 MHz.
  • Caution
    • When you use the antenna to transmit, you must always collapse the section located just above the loading coil. If you do not collapse this section, you might damage the antenna and your radio.
    • When you use the antenna to transmit, you must calculate the 1/4 wavelength and adjust the antenna length accordingly. If you do not do this, you can damage your transmitting equipment due to an improper standing wave ratio (SWR).
      • Use this formula to calculate the proper length for a 1/4 wavelength transmitting antenna: 2834 / Freq. in MHz = Antenna Length in Inches 
Common 2m Band Antenna Lengths
  • 144.000 Mhz --> 19.7 inches
  • 144.500 Mhz --> 19.6 inches
  • 145.000 Mhz --> 19.5 inches
  • 145.800 Mhz --> 19.4 inches
  • 146.520 Mhz --> 19.3 inches
  • 147.570 Mhz --> 19.2 inches
  • 147.990 Mhz --> 19.1 inches

When receiving only:
  • 25 Mhz to 136 Mhz - Extend all nine sections of the antenna
  • 136 Mhz to 174 Mhz - Extend only the top four sections
  • 174 Mhz to 1296 Mhz - Extend only 1 to 3 lower sections

Good DX and 73, NJ2X

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. 

Diagnosis

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.

Repair

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

Results

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,  
NJ2X



November 23, 2018

MFJ-1886 Loop Receiving Antenna

Decided to order the MFJ-1886 loop receiving antenna to have some fun experimenting on MF and HF bands.  I have been wanting to try out a loop antenna for years and the MFJ-1886 fit my requirements.

Requirements

  • Magnetic loop antenna design
  • Cover the medium wave broadcast band (525 kHz to 1705 kHz)
  • Cover the high frequency band (1700 kHz to 30 mHz)
  • Directional capability
  • Compact size
  • Weatherproof for outdoor use
  • SO-239/PL-259

Looking forward to giving the MFJ-1886 loop antenna a complete workout with MW DXing and shortwave listening.  Stay tuned for follow up articles.

MFJ-1886 Receiving Magnetic Loop Antenna


Good DX and 73, NJ2X

February 4, 2018

Azden AZ-61 6m FM HT - Tip #14 - Antenna

Azden AZ-61 6m FM HT

This is an article in a series regarding the vintage Azden AZ-61 6m FM Transceiver.

The Azden AZ-61 comes with 50 Ohm BNC antenna connector and a rubber duck style antenna.  An excellent way to get more out of this radio is to upgrade the antenna.  There are several 6m BNC antennas on the market or you could build your own.

KC0BIN (Rob) contacted me recently to share that he has had very good results with the Diamond RH-205 BNC antenna on his Azden AZ-61.  The antenna telescopes out to about 52.75 inches, and this length coincidentally resonates well on the FM portion of the 6M band.  Thank you, Rob, for this helpful tip.



Good DX and 73, NJ2X


Other related articles on NJ2X.COM:
Azden AZ-61 6m FM HT - Tip #1 - How to program the radio
Azden AZ-61 6m FM HT - Tip #2 - disabling "the beep"
Azden AZ-61 6m FM HT - Tip #3 - 1993 review article
Azden AZ-61 6m FM HT - Tip #4 - rebuilding the battery pack
Azden AZ-61 6m FM HT - Tip #5 - how to reset the radio
Azden AZ-61 6m FM HT - Tip #6 - Automatic Power-Off
Azden AZ-61 6m FM HT - Tip #7 - VFO Mode
Azden AZ-61 6m FM HT - Tip #8 - Frequency Step
Azden AZ-61 6m FM HT - Tip #9 - Scanning
Azden AZ-61 6m FM HT - Tip #10 - Dual Watch
Azden AZ-61 6m FM HT - Tip #11 - Battery Saver
Azden AZ-61 6m FM HT - Tip #12 - Optional Accessories
Azden AZ-61 6m FM HT - Tip #13 - Specifications


© Michael W. Maher and NJ2X.COM, 2017. 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.

September 6, 2015

Using a Diamond HV7A Mobile Antenna as a stealth base antenna

We recently had need for a multiband stealthy antenna covering 70cm, 2m, 6m, 10m, and 20m.  The stealth requirement meant that the antenna had to be near invisible on a rooftop as seen from the ground level.  After evaluating our options (beam, traditional full-size base vertical, wire) we were unsatisfied.  None of the choices seem to meet the prime criteria of invisibility.

This prompted us to consider the use of a multiband mobile antenna which tend to be constructed with a minimal profile.  We eventually settled on the Diamond HV7A as it offered multiband coverage that met our needs in a rather stealthy package.

Diamond HV7A Mobile Antenna in its packaging

Diamond HV7A Mobile Antenna unpacked

HV7A Mobile Antenna assembled and ready for mounting

We mounted the antenna on our rooftop and it was amazingly difficult to see from the ground level.  This was exactly what we had hoped for in terms of physical appearance.  We have been satisfied with the HV7A though performance as a stealthy base antenna is a compromise due to its intended purpose as a mobile antenna.

 Antenna_BandFrequency Coverage RangeVertical Antenna GainElement Phasing (wavelength)Antenna Power Rating
10 meters28-29.7 MHz2.1 dBi1/4120 watts
6 meters50-54 MHz2.1 dBi1/4200 watts
2 meters144-148 MHz2.1 dBi1/2200 watts
70 centimeters440-450 MHz5.5 dBi2 x 5/8200 watts


Good DX and 73, NJ2X

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:

START
  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
STOP
  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.
CONTINUE
  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



© 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 19, 2012

DXCC Completed!

We are celebrating in the shack today on completing the requirements to earn the ARRL DX Century Club (DXCC) award. The DXCC award is a worthy challenge. To earn the ARRL DXCC award a ham must confirm 100 contacts each from a qualifying different DX entity. These entitities are defined in the DXCC list. To qualify, an entity must have some definable political or geographical distinctiveness.


Proof of a confirmed contact can be either a paper QSL card or a Logbook of the World (LoTW) QSL.  We are a big fan of the ARRL's LoTW so for an extra challenge we decided to we would confirm 100% of our qualifying DXCC contacts via the LoTW (and not use any paper QSL card confirmations).  This proved to be more of a challenge than we anticipated since we had to complete several contacts with many DX entities before locating a LoTW subscriber.

We also decided to make all of our contacts using transmitter power of 100W or less and with a simple wire antenna.  This meant we would not use amplifiers, towers, beam antennas for the DXCC contacts.  We were interested in demonstrating that the ARRL DXCC award is within the reach of hams with modest stations (like ours).

Today we filed our application when the 100th qualifying contact was confirmed in the LoTW.  Our award is #57,420.  What a great feeling!

Good DX and 73, NJ2X


PS: In 2012, the DXCC Desk processed 14,301 applications, comprising 1,491,661 QSOs.



© 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.

November 6, 2012

Scientifically Verifiable Fact: Best Antenna for Amateur Radio Use

We hams are tough customers when it comes to antennas (also known as the great interface to the universe or GITTU).  It is often the case that the superior performing antenna is the one you would like to put up next and the under-performer is the one you put up last.  Simply put, a ham is never satisfied.  For many, that is part of the attraction to radio.  A station can always be improved, modified, enhanced, augmented, tweaked, repaired, ... until the bank account is minus-zero or we are SK.

From time-to-time it is helpful to remind ourselves that the GITTU we have is better than the one we don't.  The scientifically verifiable mathematical proof of this is that you can make contacts with the GITTU you have and you cannot make contacts with the GITTU you don't have.  So get on the air and give your GITTU a workout.



Good DX and 73, NJ2X



NJ2X Note:
Gentle reader, you may be wondering why we used the 5 letter acronym, "GITTU" when the generally accepted acronym practice (known as GAAP) is a TLA or Three Letter Acronym?  In our age of ever inflating bigger badder government, taxes, spending, deficits, and entitlements, the lowly TLA alphabet soup is simply passe.  The world needs 66% more of everything so the 5 letter acronym (or FLACC) is the new normal.

October 28, 2012

Considerations For A New Antenna - Part 2: Installing a 6m Antenna

In "Considerations For A New Antenna - Part 1" we discussed the criteria and considerations for setting up new antennas in our new location.  In this article, we share how we went about setting up our first antenna in the new location.

We decided our first effort would be to set up a 6m ground plane antenna on a mast mounted on top our chimney.  6m is a wonderful band offering DX possibilities along with access to local repeaters.

For this project we would need:
  1. 6m ground plane antenna
  2. Chimney mast mounting kit
  3. Standard 1.5 inch x 5 foot antenna mast
  4. Low-loss 50-ohm coaxial cable (we use Bury-FLEX 1.1 dB of attenuation /100 FT at 50 Mhz)
  5. UHF connectors
  6. 8-foot copper clad steel ground rod
  7. Lightning arrestor (we use ICE coaxial lightning/EMP suppressors)
  8. Solder
  9. Soldering iron
  10. Electrical tape
  11. Self-sealing silicone rubber tape
  12. Ladder
  13. Rope and bucket
  14. Crescent wrench
  15. Leather work gloves
  16. Pair of HT's (optional)

Parts

In days gone past, items such as chimney mast mount and masts were commonly available in local hardware or electronics stores serving the needs of customers with TV antennas.  We went shopping in local area stores and found none had chimney mast mounts or even 5 foot antenna masts; though, they did have an 8-foot ground rod.  The ubiquity of cable TV seems to have reduced the need for TV antennas.  Thankfully, these items are still available through Internet retailers.

We ordered a Ronard chimney mast mounting kit and Winegard 5 foot mast and they arrived quickly.  The Winegard mast was more substantial than expected.  The mast was 18 gauge steel tubing without any visible seem.  The Ronard chimney mast mounting kit included stainless steel straps and heavy duty hardware.  The chimney mast mounting kit included very basic instructions for setting up the straps.

We had picked up an older 6m ground plane antenna brand new in the box at a ham fest several years ago for $20.00.  We had used this antenna with a 18 foot painters pole for an easy-to-setup ARRL Field Day antenna.  We used our MFJ-269 antenna analyzer to cut the antenna centered around the SSB DX calling frequency of 50.125 Mhz (see 6m band plan below).

We also had a lightning suppressor, electrical tape, self-sealing silicone tape, coaxial cable, UHF connectors, and the tools already available in our shack.

Safety First

Amateur radio is generally a very safe activity.  There are potential risks to consider and take the necessary precautions.  Among these is coming in contact with high voltages and currents, falling from heights, and having something fall on you.  Our motto is, "safety first" and this mindset helps us avoid accidents.

Installation Preparation

The first step was call the local utilities and request them to identify buried cables and gas lines.  They came out within a few days and marked everything clearly with spray paint and flags.

We next surveyed the work areas looking for hazards. It is critical before starting to make sure that any new antenna installation cannot come in contact with overhead wires or buried utilities.  We confirmed that no hazards were present.

We assembled all the parts and tools at the base of the chimney and enlisted a helper.  This job could be done by one man; however, two hams are better than one.  It is considerably safer to work with a helper since ladders and heights are involved.

We also brought out a pair of 2m HT's to aid with communication between the roof-top work and the ground-work.  This is so much effective than yelling back-and-forth at the top of your lungs and being misunderstood.  We are hams after all.  There is typically a fair amount of wind noise up on a roof that can interfere with being heard without the aid of a radio.  This helped avoid a comedy exchange, "I said, send up a WRENCH not go sit on the BENCH!!!" or "What was that?  Did you say, GO! or NO!?"



Installing the Chimney Mast Mount

The Ronard chimney mast mount included directions for fastening the stainless steel strap to the strapping clip.  However, no other directions were provided.  The mount itself is a fairly simple device and perhaps assembly is self evident.  Installation is another matter.  Installing the mount took a bit of trial-and-error to get it right.  Here are a few things we learned:
  • Wear leather gloves when handling the stainless steel strap.  The strapping is razor sharp.  We didn't think to bring gloves to the roof top and by the time the installation was complete our hands had a dozen or so nicks.
  • Pre-bend the strapping into shape before placing around the chimney.  The strapping wants to return to its coiled shape unless you counter this with new bends.  It is much easier to handle the strap when it is in the approximate shape of the chimney than if it is in the approximate shape of a tightly wound coil.
  • Wire cutters won't cut stainless steel strap.  Perhaps there is a better tool?  We didn't discover this until we were on the roof so we ended up using metal fatigue to break the strapping in the desired place. 
  • Prepare the strap and strapping clips on the ground.  If we had it to do over again we would pre-cut the strap to the desired length and pre-install the strapping clips all on the ground.  This would avoid the possibility of losing one of the small clips on or over the side of the roof.  It would also be easier and provide more convenient access to tools in the workshop.
  • We kept our hands free while climbing the ladder and roof and used a rope and bucket to hoist up parts and tools from the ground.  Here is our helper made the biggest contribution.


Installing the 6m Ground Plane Antenna

Attaching the mast and ground plane antenna was the easiest part of the installation.
  • Build the antenna on the ground.  The antenna has 5 main parts that needed to be assembled.  Once assembled the antenna is light and somewhat bulky.  We choose to build the antenna on the ground for ease and safety.
  • Hoist up tools to the roof with the aid of a bucket and a line.  Communicate with the helper on the ground with an HT.  Make sure the helper stands well away from the roof line or where anything could fall.
  • Hoist the mast from the ground to the roof with a line.  We passed the line through the mast from one end to the other.  We tied a wooden dowel to the rope at the end of the mast and hoisted it up.  This kept the mast in the same orientation as the line and made it very easy.
  • Hoist the antenna from the ground to the roof with a line.  We tied the rope to the bottom of the antenna and also at the top.  This allowed for an easy hoist in a vertical orientation to the roof.
  • Hoist the coaxial cable from the ground to the roof with a line.  We tied the rope to the coaxial cable and hoisted it up with ease.  Take care there are no twists in the coax that could turn into a kink (bad for coax) while hoisting.
  • Seal the coaxial connection.  Some people prefer coax seal.  We prefer applying a couple of tight layers of good quality electrical tape followed by a wrapping with self-sealing silicone tape.  This will prevent water intrusion and corrosion. 
  • Secure the coax to the mast with electrical tape or cable ties.  This prevents the coaxial cable from bouncing around against the mast in high winds.  Provides some strain relief as well.
6m Ground Plane Vertical Antenna Close Up

Installing RF Grounding System

We used a step ladder to stand on to drive the 8ft ground rod with a 8 pound hammer.  This made it easy to keep the hammer on-target as it went into the ground.  We switched to a larger sledge to drive the last foot or so.

We attached an ICE suppressor bracket with 2 ICE lightning suppressors mounted to the top of the ground round.  One lightning suppressor for use on 6m and the other for an HF antenna.

We placed the lightning suppressor and cabling within an enclosure to provide some protection from the elements.

Lightening arrestor system

First 6m QSO

We connected the cabling to our Kenwood TS-480SAT and powered up.  We had a local Pittsburgh 6m repeater already programmed into memory (51.740 Mhz with a PL tone of 100.00 Hz) so we dialed it up and found a group of hams in a ragchew.  So far so good on receive.  We were wondering if the antenna would tune up and transmit?  We hit, "tune" and sure enough it tuned immediately.  This was a good sign that everything was in order.  We waited for a pause and then transmitted giving our call.  One of the hams came back immediately acknowledging our call and inviting us into the group.  Voila!  6m ground plane vertical antenna project success!

6m Ground Plane Antenna mounted on chimney

Since our first QSO, we have enjoined joining into the Pittsburgh 6m repeater net and finding a few other local 6m repeaters we can reach.  We are also eagerly awaiting a 6m opening when we can give 6m DX a workout with the new antenna and make progress toward our ARRL 6m DXCC award.

The 6m band is the "magic band" and has something to offer everyone - from DX'ing, repeaters, ragchew, CW, digital, ...

ARRL 6 Meter Band Plan, 50.0-54.0 MHz 50.000-50.100 CW and beacons
50.060-50.080 Automatically controlled beacons
50.100-50.600 SSB 50.125 SSB DX calling frequency 50.200 SSB domestic calling frequency (Note: Suggest QSY up for local & down for long-distance QSOs)
50.600-51.000 Experimental and special modes 50.700 RTTY calling frequency
50.800-50.980 Radio Control (R/C) channels, 10 channels spaced 20 kHz apart (new)
51.000-51.100 Pacific DX window
51.000-52.000 Newly authorized FM repeater allocation
51.100-52.000 FM simplex
52.000-52.050 Pacific DX window
52.000-53.000 FM repeater and simplex
53.000-54.000 Present radio control (R/C) channels, 10 channels spaced 100 kHz apart

Shortwave Reception

An unexpected side benefit was the antenna's receive capabilities.  While tuning around HF we discovered the antenna performed nicely as a shortwave receive antenna.  We were surprised how well it received shortwave stations.  We attribute the quiet performance to having a good RF ground and installing the antenna above the roof line.  In the past, we have always used horizontal wire antennas (i.e. long wire, dipole, and fan-dipoles) for shortwave reception.  This antenna has given us a new appreciation for a VHF vertical for shortwave reception.  This is also something to keep in mind when in an emergency situation - a VHF antenna is an asset for both VHF and HF reception.

73,

NJ2X


The NJ2X Kindle Edition is now available.



© 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.

October 24, 2012

Antenna Coaxial Cable Conduit Fill Considerations

Conduit fill is the percent of the area inside the conduit taken up by cables.  Conduit fill is an important consideration when selecting and planning your antenna projects since it is not possible to use 100% of the conduit's area.  There is no sense in going through the expense and effort of trenching, laying conduit, and pulling your antenna coaxial cable only to find later that the conduit is too small to support the area consumed by the cables.
We recently ran across two handy Internet resources related to conduit fill: Conduit Fill Chart and Conduit Fill Calculator.


Here is an example of the conduit fill calculators output:

The conduit fill is: 17.9%

Based On:
Conduit Type: Rigid PVC Conduit, Schedule 40
* Conduit Size: 2 inch(es)
Internal Diameter: 2.047 (in.)
Conductor #1: 3 conductors with an outside diameter of .5 inches.
Conductor #2: 0 conductors with an outside diameter of 0 inches.

**Warning: There is some probability of jamming.


73,

NJ2X






September 15, 2012

Considerations For A New Antenna - Part 1

Our shack was disassembled, packed up in boxes, and out-of-use for several months due to relocation.  We recently hit our tolerance threshold for being off-the-air and decided to take action and reassemble a station.



Nothing like a huge maple to hoist up the center of a fan-dipole.  Unfortunately, our new QTH doesn't have large trees to support our excellent Alpha-Delta antenna.  This has led us to spending some quality time reading our 21st Edition of the ARRL Antenna Book to gather up different ideas.

Our design criteria:
  • No tower
  • Multi-band (as many as possible)
  • Effective for DX'ing including all 50 States
  • Durable in a permanent all-weather installation (e.g. rain, wind, snow, ice, ...)
Considerations:
  • No trees suitable for hanging an antenna
  • Large hill rising to the North and falling to the South
  • Tall chimney on house
  • 150 feet of back yard

 In part 2 of this article series, we will select and install our first antenna in the new location.




July 6, 2012

So what happens to window line in a lightning strike?

So what happens to window line in a lightning strike?

We had the opportunity to inspect sections of window line that had been subjected to the effects a lightning strike.  Interestingly, the copper wire was completely absent from the plastic.  Copper vampires?


There were a few clues.  The first clue was in the form of copper color specs on the insulation - almost as though it had been lightly and randomly sprayed on by a spray can.  An additional clue was the plastic which showed evidence of violent heating and had two burnt tracks running along where the copper had once been.

All the clues pointed to the copper having been completely vaporized in an instant by the lightning.  This must have been an incredibly violent moment and would have been frightful to witness.  Lightning is an extremely powerful force - it can have 100 million to 1 billion volts, and contains billions of watts.  As lightning passes through air, it can heat the air to 50,000 degrees Fahrenheit: about 5 times hotter than the surface of the sun.

We noticed that AE5X had a similar experience which he posted on his blog.



March 11, 2012

Weatherproofing Coaxial Cable Connections

Weatherproofing your coaxial cable connections is absolutely essential to avoiding moisture  damage which can result in high SWR and other problems which diminish your system performance.  DX Engineering has published a helpful document showing how to do it correctly and effectively.  Be sure to give this a read:

DX Engineering - Weatherproofing Coaxial Cable Connections

Weatherproof cable antenna connector box

Winter has a way of accelerating the deterioration of cable weatherproofing.  With the return of Spring and warm weather (at least here in New Jersey), this is an excellent time to get out and inspect and maintain your coaxial cable connections and weatherproofing.  A few minutes of preventative maintenance is a low cost way to assure your cable system continues operating at peak performance.

73,
NJ2X

February 9, 2012

Ab Absurdo - HOA Friendly Low Profile Antennas






© 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.

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, 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...

73,

NJ2X





© 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.

November 23, 2011

Chasing 10m FM DX

There are so many interesting modes in which to operate our amateur radios.  Most hams are familiar with the "meat-and-potatoes" modes like, CW, SSB, AM, and RTTY.  Surprisingly, few hams seem to have tried working DX with FM.  The return of sunspots provides ham with an opportunity to jump into FM DX'ing.  You can work 10m FM DX with a modest station - a 100W rig and an 10m antenna will do the job.

You can even work QRP (low power < 5w) FM DX when the 10m band is open.  This is really amazing thing to experience.  Give it a try sometime.  One approach is to start the QSO with higher power and then back the power level down to QRP and see if you can maintain the contact.  How low can you go?  Another approach is to simply work the contact with low power.

Kenwood TS-480SAT HF + 6m Transceiver
Kenwood TS-480SAT HF + 6m Transceiver

Generals, Advanced, and Amateur Extra's have HF FM privileges on the 10m band.  The United States HF band plan allows FM between 29.6Mhz and 29.7Mhz.

5 Tips for 10m FM DX
  1. Keep the QSO short  - 10m FM DX is fast paced since the conditions are typically unstable.  Make the exchange quickly so you can log the contact.
  2. Monitor beacons for 10m openings - When 10m is open, dial up the 10m FM band plan frequencies.
  3. Monitor spots for 10m FM - Monitor 10m spots and look for frequencies that fall within the US FM band plan.  Once you see a spot, move quickly as the station will often disappear quickly.
  4. 29.600Mhz is the FM simplex calling frequency.  This is a good place to start listening.
  5. Dial up-and-down.  FM simplex changes quickly.  Stations will appear and disappear.  Keep moving, listening, and pounce.
On November 20, 2011, we had a great time making 10m FM contacts with Europe including OK2OV (Czech Republic), PB2A (The Netherlands), and GI7AXB (Northern Ireland).  All of these contacts were with full quieting and rich audio.  10m FM DX can sound awesome!

If you have a 10m radio with FM, we encourage you to get onto 10m and try working FM DX.  You will be amazed that this typically local mode works so well over great distances.  You will also enjoy the nice clean sound of FM too.

© Michael W. Maher and NJ2X.COM, 2011.

November 1, 2011

Antenna survives the NJ October snow storm

Kudos to Alpha-Delta for building such a tough antenna.  Once again our Alpha-Delta DX-LB Plus Parallel Dipole survived another dish of what mother nature was serving here in New Jersey.  This time it was a heavy snowfall (6 to 16 inches around the state) on October 28 and 29, 2011.  The end of October is normally a lovely time of year with with pleasant temperatures and mostly green trees.  We haven't had a snowstorm in October since 1987.  Lets see what the winter will bring.

Alpha-Delta DX-LB Plus Parallel Dipole Antenna

73,
NJ2X