40-Meter Dipole … Fail!

At our previous address I built a 40 meter dipole that worked somewhat well. I was able to make a few contacts even though the band conditions over the summer were very poor. At least the afternoon Hawaii net on 40 meters was workable. The antenna apex was about 25′ above the ground and the legs in a sloping inverted V configuration coming down to about 10′ above the ground. The antenna was oriented northwest to southeast which would put the major lobes towards North America and towards New Zealand and Australia. The SWR measured between 1.3:1 to 1.5:1 across the 40-meter band. It also had similar SWR on 15-meters.

Then came the requirement to move. I tried to put the same antenna up here. Because of limited places to guy the painter pole holding the apex of the antenna, I was only able to get it about 18′ above the ground. The legs were again in an inverted V configuration, but also angled away from the antenna. Rather than having a 180° spread, the angle was closer to 150° on one side and 210° on the other. The antenna also was in an east/west orientation, meaning the main lobes (what there was of them) went north and south. Further, at that height, the takeoff angle was no lower than 60° making the antenna at best NVIS. The legs were attached to an 8′ 2×2 board velcro’d to the fence and had to go through quite dense foliage. I had 50′ of Radio Shack RG-8u coax to go from my Yeasu FT-897D to a 1:1 current balun at the apex of the antenna, meaning that about 30′ of coax was coiled on the floor behind the radio.

The SWR was horrible; resonance was 7.045 Mhz with an SWR of 7.3:1, too high for the built-in tuner to accommodate. I have an MFJ-971 portable tuner that I bought to use with my (still in the box, not yet powered up) Xiegu X1M Pro QRP transceiver. With that I was able to bring the SWR into a more reasonable range, but the SWR fluctuated across a very wide range from the wind in the foliage. Further, the coil of coax was also acting as an inductor with a lot of capacitance further screwing up the signal. I then picked up at 20′ piece of Radio Shack RG-8u coax, that improved the power output considerably, but the FT-897D did not like the SWR fluctuation at all. The antenna was simply non-functional. Down it came.

As an aside, we have an excellent Radio Shack about a half-hour away to the northwest in Hale’ewa. This is one of about ten still open stores in Oahu, but the only one that actually stocks parts. All the other stores are concentrating on selling cell phones and audio cables with literally no other stock. The store in Hale’ewa, however, keeps a fully stocked parts section. I love that store!

I have a Buddipole antenna system, the “long” version. It works very well, but takes me a half hour to get set up, guyed down, and tuned. It’s not at all advisable to leave this antenna up in the Hawaiian salt air / volcano ash / frequent rain showers weather. That was the reason for thinking about putting up a 40-meter dipole so when I had a few minutes I could sit down at the radio and see what was happening. As we move into “winter” (a strange term in Hawaii), band conditions will favor 40 and 80 meters.

I may still try to find a way to get a north/south orientation and trim that 40-meter dipole down into a 20-meter configuration. A 20-meter dipole is quite a bit shorter … we’ll see. We’re only here in Hawaii for 4 more months and then will be moving back stateside.

2 Meter / 70 CM J-Pole Antenna Back Up

This antenna is a J-Pole antenna I purchased on the Internet in April, 2015 from Arrow Antennas after I arrived in Hawaii. I have a similar antenna in storage back on the mainland. I’ll leave this antenna here with someone who needs one when I leave in February, 2017.

HF Dipole Mount
HF Dipole Mount
I decided to put this antenna on top of a 16′ painter pole I was going to use for my HF dipole antenna. The dipole mount wouldn’t be in the way of attaching the J-Pole above it.

J-Pole Attached to the Painter Pole
J-Pole Attached to the Painter Pole
The aluminum bracket to to attach the J-Pole fit nicely onto the painter pole. However, the bolts supplied by the manufacturer weren’t threaded the entire length and I ran out of thread before the bracket could be firmly attached. Another (!) trip to Ace Hardware to buy two more fully threaded bolts ($1.07 including tax) solved that problem.

Support Post Pounded Into the Ground
Support Post Pounded Into the Ground
I wanted the installation to be removable when I leave next February with literally no trace left behind. I decided to put a post in the ground, a PVC pipe on the post, and then insert the pianter pole into the PVC pipe. I could then attach the pole to the roof at the 10′ level and use two guy ropes at the 16′ level to help stabilize the pole. I bought a four foot dowel 1 1/2″ in diameter, cut a point into one end, and then pounded it into the ground about 18 inches. That would provide the bottom support. The house has a small sidewalk that goes along the side of the house. The edge of the roof overhang is directly above the edge of the sidewalk. Consequently the antenna pole would go straight up past the roof where it could be attached.

PVC Pipe Support
PVC Pipe Support
I next cut a four foot section of 1 3/4″ PVC pipe from Ace Hardware. That slipped over the dowel. The dowel stood about 2 1/2 feet above the ground. The painter pole would be inserted into the PVC pipe and rest on top of the dowel. The painter pole is about 1 5/8″ in diameter, a nice tight fit into the PVC pipe.

J-Pole Antenna Erected
J-Pole Antenna Erected
The painter pole is inserted into the PVC pipe, attached to the roof, and stands about 18′ tall. Two guy ropes go from the top down to the edge of the roof to provide additional stability (the picture was taken after the pole was secured to the roof.). The guy ropes are hanging down in the picture and were attached to the edge of the roof after the picture was taken. The ropes from the pulley are for the HF dipole antenna that will be put up next.

There are three repeaters in the area that can potentially be reached from my location. One is about a mile away at BYU-Hawaii campus. Another is thirteen miles west. That repeater is currently running low power because of a problem with the amplifier. When that gets fixed (it’s been down for several months) and I can finally hear it again, that repeater is linked into the state-wide emergency network of repeaters. Finally there’s another repeater nineteen miles south which I can now reach with this antenna.

2 Meter Ground Plane Antenna

2 Meter Groundplane Antenna
2 Meter Groundplane Antenna

Because of the move from Laie to Hau’ula a couple of weeks ago, I had to take down my antennas and put them back up again in the new location. The first antenna to go back up and into operation is a 2 meter ground plane antenna.

I took the original idea for the antenna from an article on hamuniverse.com. I bought some 14 gauge bar wire and some small bolts and nuts from Lowe’s along with 25′ of RG58 coax and an SO239 panel adaptor from Radio Shack. I built it as described in the link.

2 Meter Ground Plane Base
2 Meter Ground Plane Base

I threaded the coax up through a two foot section of 1″ PVC pipe from Ace Hardware. I used Gorilla Duct Tape (also from Ace) to hold the SO239 down on the top of the PVC pipe. Since the coax has PL259 connectors on either end, it mated up very nicely with the ground plane antenna.

The PVC pipe is attached to a 12′ painter pole that I bought at Lowe’s for this purpose. I drove a 1 3/4″ piece of PVC pipe (also from Ace) into the ground so that about 18″ were above the ground and stuck the bottom of the painter pole into the PVC pipe and the attached the pole to the fence. It has very low wind loading and has stood quite firm during the recent tropical storm that came through.

Erected 2 Meter Ground Plane
Erected 2 Meter Ground Plane
This antenna is one of four antennas going up at my new address in Hau’ula. This antenna is connected to a Motorola 2 meter radio operating simplex on 147.450 Mhz attached to the AllStar network via a Raspberry Pi. See the AllStar category for information on that setup. The antenna has been an excellent performer. Together with the 20 watts output from the Motorola radio, I have excellent coverage throughout the Hau’ula and Laie area.