SSB Finishing Touches

 
Down below at the Nav Station I'm making the power connection to the house bank batteries.  The transceiver draws about 25 amps while transmitting and has a 30 amp fuse on the positive power input.  They provide about ten feet of #10 wire but I'm using #8 for most of the run to ensure adequate voltage levels.  Coming from the batteries located beneath the starboard settee the wire runs through 40 amp fuses, one for each leg.  This is simply to protect the wiring in the event of a short.  From there it runs up to a terminal strip near the transceiver where it mates with the now shortened #10 wire.  I used non-insulated ring lugs with shrink wrap on all wire terminations.  Using #8 wire required some heavy duty crimping and I ended up investing in a ratchet type crimping tool.  Money well spent.  For the shrink wrap I used Cheri's blow dryer.  Not as fast as a heat gun but it did the job.  After I made some voltage checks I went back and dressed out all the cable runs and neatened things up.

Another connection on the transceiver is for GPS information.  This is displayed on the head unit screen as latitude and longitude and also used in DSC mode so your position is automatically transmitted.  Both our VHF and SSB radios have DSC capability.  To get the GPS info I'm tying into the NMEA 2000 backbone using a gadget from Raymarine called a "VHF NMEA 0183 to STng converter" (p/n E70196, $75).  Only one of these is required for both radios.  The input side provides the GPS info and the output from the radio provides location information of the vessel you're in contact with.  This might be handy if you're traveling with a group of boats and keeping in touch using the DSC mode.  If you're spread out over 20 miles of ocean each boat will still be displayed and identified on your chart plotter with pop-up flags containing all the boat's information. Pretty sweet!

The final connection is for the modem, in our case a Pactor-4 Dragon DR-7400 from SCS (click here).  This little unit allows the SSB radio and our Mini Mac computer to communicate, giving us the capability of sending/receiving e-mail and downloading weather information.  This thing costs as much as the radio itself but this is the main reason we wanted a SSB radio, being able to stay in touch with friends and family by e-mail, even when we're away from a WiFi connection.  Maybe just as important is the ability to pick up weather forecasts anywhere in the world.  This little box is a key component for our travel plans.

Once I finished up all the wiring down below I went back topsides and completed the connections in the cockpit locker.  All our wiring runs through the genset compartment so I needed to pull the genset forward to allow me to get in behind it to finish the job.  This is a tight space requiring the dexterity of a contortionist and made it obvious to me that I'm really getting too old for this kind of stuff.  I can get into the tight spots but then it's a major struggle to get back out.  It wasn't that long ago that I could do this stuff, no problem.  Getting old sucks.

The mounting board has had over a week for the 5200 to set so I went ahead and mounted the antenna tuner in the starboard side lazarette.  The location I settled on is basically up inside the aft coaming.  This works well for a short direct run to the backstay but once it's mounted on the board most of the connections are facing away towards the center of the cockpit and have to be made by feel.  The only really difficult part was the wing nut for the ground connection.  Because of it's shape it's pretty tough to get it started and I managed to drop two of them before finally threading it on properly.  This is one of those locations where anything that falls instantly rolls out of sight, in this case under the genset.  At $2.42 each, it's already an expensive collection down there.

At the ground lug I made connections for RF ground and the green wire for the control cable.   The RF ground is a critical component in the SSB antenna system.  The actual back-stay wire between the insulators is really only half of the antenna.  The other half is the ground which enables the RF signal to jump free of the antenna.  A really good ground is key to having a good, clean and strong signal.  It's important to understand that to keep system noise to a minimum an RF ground needs to be separate from all other grounds on a boat, including the batteries, engine and bonding system.  There are different techniques for creating a suitable RF ground on a boat.  One is to mount a bronze plate on the outside of the hull below the waterline and connect a heavy gauge 4" wide copper tape between the mounting bolts inside and the ground lug of the antenna tuner.  This uses the water the boat sits in as the ground plane and is pretty effective.  The drawback is that the bronze plate requires cleaning.  Another method is to run that copper tape along the inside of the hull and connect it to through hulls and deck mounting plates.  They recommend you use about 100' of copper tape for this.

I'm going to try something a little different called a counterpoise made by KISS-SSB (click here).  This is a series of wires cut to exactly 1/4 wavelength for the most common frequencies used on the SSB radio.  The tuned wires are contained in a heavy tube about 9' long that is run inside the hull and connects to that same ground lug.  This sells for $149, requires no holes in the hull and installation takes about 10 minutes.

The high voltage output at the other end of the antenna tuner was pretty straight forward.  It has a boot that slips over the insulator to prevent any moisture running down the wire from getting inside the tuner.  It's designed so it can be mounted outside in the weather and that would explain the need for the boot.  Probably not needed in this location but it went on anyway.  I drilled through the back side of the coaming and installed a weather-proof feed through.  The wire used to connect the antenna tuner to the back-stay is GTO-15, originally designed for use with neon signs.  Since this is a high voltage cable I ran it through conduit with 1.625" stand-offs attached to the non-insulated part of the back-stay.  I placed the stand-offs every 6" to give the conduit plenty of support and it's strong enough to be used as a grab handle while moving around the cockpit.  The conduit exits through a PVC cap at the top of the conduit just above the bottom insulator and makes a gentle 180 degree turn before connecting to the back-stay with a "GO-To Bug" clamp.  I sealed it up with tape but then read the "Sailor's Quick-Start Guide" where I found that this clamp is supposed to be left exposed to weather to keep it accessible for cleaning on a regular basis.  OK, gotta go back and fix that.

The final part of my work this weekend involved installing an earth ground for the antenna tuner.  I decided to go with this after discussing it with some friends with the same SSB radio and KISS counterpoise.  The radio comes with 10' of 4" wide heavy copper foil.  I ran this from the ground lug on the tuner down to the packing gland nut on the rudder post.  Anywhere it changed direction I folded it over on itself to form a 90 degree turn.  At a convenient spot I cut the tape across and mounted it to a block of wood, leaving a gap between the two ends.  Across this I soldered four capacitors (0.15uf, 100v) to create a DC block that will prevent electrolytic corrosion. I then covered the edges of the foil with Gorilla tape to hold it in place and prevent injuries from the sharp edges.

As I was cleaning up at the end of the day I found the wingnuts I had dropped, both securely wedged in the wiring beneath the genset.

We fired up the radio and did a listen test to see if we could hear anything.  Picked up some dudes chatting down in Miami.  Cool!  Now I gotta learn what all those knobs and buttons do so we can do some chatting of our own.