David,
Re: Noise & radio freq.... turn off everything don't forget your digital watch...
A very good idea! I have the same setup. My SSB is wired with greatly oversized wires and is a short run directly from my 500 amphr AGMs. I have to remember to turn stuff back on too. That is the only disadvantage.
That Rope Antannae website suggests fuses, not circuit breakers and to put a fuse in EACH LEG of the power to the radio.
I am still trying to find out why.
I have studied the Near Field and Far Field of our Monopole Antennae setups on our boats recently. From what I can glean through all the noise of misinformation (seems to be a great deal of wrong advice) we have a half wave dipole antennae that has one leg grounded to the seawater. So, in essence, we have a quarter wave MONOPOLE with the emitting leg above seawater and the other leg grounded to the seawater. Our job is to match that antennae to the Impedance of Free Space = 377 Ohms.
Our Antennae Tuners try to do this. But we must make their job as easy as possible.
According to Maxwell's Equations and antennae theory the Near Field is reactive up till 2 to 3 wavelengths from our Monopole emitting leg. So at 20 meters x 3 that is a circular area about 60 yards in radius around the boat that DOES NOT HAVE the Radiative Skywave coupled to free space as of yet. Once the Electromagnetic Wave is completely Far Field and radiative it is travelling at light speed and it's Elec and Mag fields are fully in phase. Then it can reflect off the highly conductive seawater and launch into space to reflect off the E layer of the ionosphere.
So any copper foil in the boat is NOT SEEN by this Radiative Far Field!!!!! Wow! The Reactive Near Field is a different animal.
One MUST connect the ground output of our Antennae Tuners directly to the conductive seawater by wide copper foil.
NOTE .....DIRECT. Capacitive grounding is not effective. Gordon West is absolutely correct!!!!
I think this is correct? Any experts out there? Please correct me if I am wrong.
I am attempting contact with Mike Trimpi. I worked with him in Antarctica. He is one of a handful of people on the planet that would really know. He can see Maxwell's Equations in his head.
The Near Field is a very complex problem with all the interactions of metal etc on a sailboat. Fields are excited in metal objects inside this volume. To see the Near Field: The Electric Field is visualized by the Fluorescent Tube held in ones hand. The high voltage excites the mercury ions and they emit UV that makes the white phosphors glow. One can see the E field and modulation of it.
The voltage in the Near Electric Field is about 900 volts or so? and the Current is in the order of 1.5 amps RF wow!
The voltage and current are out of phase in the near field. That is why the SWR is so important. Any wasted heat just diminishes your radio efficiency. Most of the 150 watts output is wasted in a bad installation. One can still get a wonderful signal report with even a very bad installation during good conditions in the ionosphere. That is why this problem is so insidious! A bad install can get a good report and for years brags about it. Then then bad procedures are proliferated.
A optimum install can get similar signal reports with only 5 watts output.
I was thinking of trying to connect my 900 volt 1.5 amp RF output to my longest shroud holding up my main mast to the chainplate below? without an insulator at bottom or top.
...problem...if I am not matched I will induce large current in my delicate wind instrument and destroy them. My whole mast would be the radiator!!!! No need for insulator on a IDEAL, PERFECT quarter wave dipole since current is zero at ends ...theoretically....but we do not live in Utopia. So do not try this at home...as they say on the Myth Busters.
Patrick
