#74 - New Antennas & Equipment
I decided to make a few upgrades to my equipment and my communications capabilities. First I will start with the updates to my antenna system here at the hamshack as well as for portable use and emcomm situations.
I have added a DX Commander vertical antenna which uses a 33 foot tall fiberglass mast surrounded by six wire elements for the 40, 30, 20, 17, 12, and 10-meter bands, but the 40-meter wire also works on the 15-meter band. It also has the ability to add an 80-meter wire in place of the 30-meter wire if desired.
Because this antenna uses multiple resonant wires as the antennas for the various frequency bands it acts similar to the way a fan dipole would excelt that it is turned on it side as a vertical instead of being stretched out horizontal. This antenna will be my main vertical antenna for the new BPQ32 bulletin board system and email server that I am setting up now, but I will get into that more in the next episode.
My main all-band vertical antenna right now is the 20' tall "Fat Spectrum" 13-Band vertical antenna which covers 160, 80, 75, 60, 40, 30, 20, 17, 15, 12, 11, 10, and 6-meter bands. I will keep this antenna as a backup for the DX Commander should anything happen to it.
I have also ordered a 50' fiberglass telescopic antenna mast for portable HF use. I am still deciding what antenna I want to utilize on this mast, I am considering an 80-meter dipole wire, fed by ladderline so that I can tune it for the 80, 60, 40, and 20-meter bands easily which are the main bands that I would be using in an EmComms situation.
I am also considering a fan dipole with pretuned wire antennas for each of those bands. I like that idea better, however by adding the additional tuned wires for each band, that also adds to the overall weight of the antenna. In this case I would basically be quadrupling it's weight over that of the single wire antenna.
Weight is a big issue when dealing with fiberglass antenna masts, especially one that is five-stories up in the air. Because Hawaii tends to get strong winds at times, especially during storms, this antenna mast will be secured by 21 guylines anchored at three positions around the mast along with a mast base anchoring system that is driven into the ground. There is also an alternate base plate version for when the antenna is set up on asphault or concrete which my communications van would be parked with the tire on top of the base plate giving it stability.
For here at the hamshack I have ordered two 40' metal telescopic antenna masts. For now I will be placing a G5RV Jr wire dipole antenna in an inverted "V" on one of them but I am considering replacing that with a fan dipole in an inverted "V" and an "L" configuration.
Setting the antenna up in an "L" pattern would allow me to have one of the ends of the antenna facing west and the other facing south. This gives me two benefits;
First it allows me to have a longer antenna wire. Because of the size of the property the antenna is being installed on I am limited to how long I can stretch a wire out in one direction. By taking the wire in two directions I can almost double the antenna's overall length.
Second, by stretching the wires to the west and the south I get closer to an omnidirectional coverage like a vertical antenna is. The horizontal wire antenna sends the majority of its signal out the sides of the wires, so the wire pointing to the south would be transmitting to the east and west and the wire pointing to the west would be transmitting north and south.
Currently I am running a G5RV Junior antenna set up in an inverted "V" configuration with the center of the antenna at approximately 16' off the ground and the ends at approximately 8 feet off the ground.
The reason this antenna is so close to the ground is that it is used primarily for local communications between the Hawaiian islands using what is known as Near Vertical Incident Skywave or NVIS propagation where instead of my signal going out from the sides of the antenna I am using the ground under the antenna as a reflector forcing my signal to shoot straight up into the atmosphere. The signal then bounces off the atmosphere back down to earth covering roughly a 500 mile "footprint" which encompasses the entire state of Hawaii.
One thing that I have noticed with this NVIS antenna is that apparently someone forgot to tell the antenna that it was NVIS because I have reached as far as the East Coast of the Continental United States (CONUS) with it already.
This antenna will stay set up as my main NVIS antenna but I will drop its height down to 14 feet from the ground to force more of the signal straight up and give me better NVIS signals.
Recently I upgraded my HF radio system to an Icom IC-7300 HF radio. The reason for this change is that the IC-7300 is one of the best radios for working digital modes which is the majority of what I do on the HF bands. I also added on an SCS P4 Dragon DR-7800 high-speed HF radio modem. The Pactor 4 DR-7800 is like the Lamborghini of radio modems. It is much faster and much more sensitive than anything else on the market, and allows me to copy and decode digital signals far below the noise level when I can't even hear the signal with my own ears anymore.
As signals begin to fade the P4 is able to lock onto the signal and hold the connection, altering the frequency of the radio slightly if necessary to maintain a good connection and a complete transmission. No other modem is able to do that.
The new radio, P4 modem, and new antennas were a huge investment but one that I feel are worth it by allowing us to have better communications in the event of a disaster or other situation where the normal modes of communications to and from Hawaii are compromised or non-existant as frequently happens after hurricanes, earthquakes, and the like.
Until Next Time
Aloha & 73 from Hawaii
