M.A.R.C.

 

The amateur radio club that promotes safety at sea through wireless communication . . .

The house with the        

sailboat in the window ...     


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SPECIAL EVENTS

 

Article:

Communications on the High Seas
by David R. Anderson, P.Eng. (VA3SSE)

 

These days it’s seems we are becoming increasingly dependent on the need to either obtain or impart information. With the advent of computers, e-mail and cell phones we are forever sending or receiving messages of one sort or another.  Stop and think about it - when was the last time that you went a whole day without checking for or sending an E-mail message?

 

So what are you going to do when you head south on that Caribbean cruise – you can’t just quit cold turkey?  Fortunately, there is a solution – you can install a single-side band system, interface it with a modem, hook up our old laptop and hey presto, you’ll be back in business.

 

This is where the fun starts – what to buy. There is an abundance of communications equipment in the market place – transceivers, tuners, modems, and computers from numerous manufacturers each claiming to be the best thing since sliced bread.  The thing to remember is that your objective is to end up with a system that works well and works reliably. Let me repeat that word – system – you don’t want to end up with an assortment of components that find it hard to co-exist with one another.

 

Today’s single-sideband transceivers are very sophisticated pieces of technology, ranging in price from $1000 to over $5,000 with many different configurations available.  As with most electronics, the price goes up with features and power capabilities.  Output power of common marine SSB equipment is 100 to 150 watts – anything more is unnecessary.

 

Then there’s the antenna tuner. An automatic antenna tuner is an essential system component. Automatic tuners use microprocessors and refined internal software to match the antenna to the transmitter. This is no small task as the impedance of the antenna system varies dramatically with frequency.  Only when the impedance is matched does the maximum transfer of power take place between the radio and the antenna system.  Without a proper match some of the energy from the radio doesn't make it past the tuner and is reflected back into the boat. (An imperfect match between the radio and antenna is one of the reasons lights on your electrical panel glow and voltmeters bounce when transmitting on a SSB.)

 

Then there’s the modem. There are a number of modems or controllers (TNC's) on the market, although the SCS PTC-II and the Kantronics KAM+ are the most popular with cruisers. The KAM+ is a second-generation controller, with a simple micro-controller and programmable analog filters. The SCS PTC-II is a third-generation controller with a powerful DSP (digital signal processor) to handle the modem functions plus a 32-bit microprocessor for the digital chores. The choice is economic, with the PTC-II offering much faster and more robust connections at a higher cost

 

– Bite the bullet and choose a Pactor II Pro, you’ll be glad you did!

 

But where to buy?  Increasingly I run into clients who “economize” by purchasing system components via the Internet – while this can sometimes result in cost savings frequently it doesn’t work out that way. You could be buying someone’s problem, warranty and after-sales support are often minimal or non-existent and typical first time SSB buyers are often lack the knowledge and experience required to select the right components.  This is often where I get called in – help – can I get the components to talk to each other and work together as an integrated system?  Much of the time it can be done, but labor expenditures eat up the component savings. In one instance I had to tell to my client that installation of the automatic tuner he had purchased could never be made to work satisfactorily with his system – he ended up selling his bargain purchase (at a loss) on E-Bay and buying the component that should have been selected in the first place.  

 

Don't underestimate the difficulty of properly installing a SSB system. It is not as technically difficult as it is laborious. Do the job well, use the proper materials and you will be rewarded with a system that will provide many years of reliable service. Cut corners and you’ll be wondering why you spent all that money on a SSB system that half the time doesn’t seem to work anyway. Self-installation of a SSB radio system will take at least one weekend for you and competent friend to install properly.  As with anything on a boat, attention to details makes a huge difference in performance.

 

The biggest challenge will likely be installing an RF Ground Plane. A good RF Ground Plane is vital to good system performance.  This counterpoise is half of the antenna system and can be thought of as the springboard used by the signal to jump off the boat and into the atmosphere. 

 

The RF ground plane installation is different for every boat but the basics are the same.  The idea is to attach all big metal items on the boat together with copper strap and end up with a minimum of 100 square feet of metal surface area.   Starting with the Automatic Antenna Tuner, the tuner should be mounted close to the feed point for the antenna, which means it is usually mounted aft.  From the tuner, copper strap will run forward and attach to the engine, any (and hopefully all) metal tanks and a keel bolt (any one will do).  Getting the copper to metal toe rails and the stern push pit along with the lifelines can be of tremendous benefit.  No Pain, No Gain.  Think metal surface area.  

 

The cost of high quality materials is minimal compared to that of your other SSB system components.  Marine materials can be expensive, but over the long haul the performance benefits are well worth the extra cost.  Tinned wire and connectors for corrosion protection, wire of the proper type and size, heat shrink tubing to keep connections dry and flat copper strap are parts of a good installation.  The basic techniques are; make good soldering connections; keep all connections bone dry and provide good electrical connection surface area contact.

 

Selecting, purchasing and installing a system that will do the job for you can be a daunting proposition.  Do yourself a favor and seek the help of your local marine HF radio specialist to help in the selection of a transceiver / tuner /controller combination that fits your needs and budget. A professional can also help you design and install the primary antenna for your vessel along with that most important item – the RF ground plane.  It’s an investment that will repay you many times over.

 

 

Terminology – what does it mean?

 

Marine Single Side Band (SSB) radio, often referred to as HF radio, is the "old standby" for cruising vessels, both small and large.  It is called HF, or High Frequency, because it uses frequencies in the range from 3 to 30 megahertz (MHz).  Medium Frequency (MF) is below HF from 0.3 to 3 MHz and Very High Frequency (VHF) is above HF from 30 to 300 MHz.

 

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COMMENTS FROM STUDENTS!

 

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UPCOMING EVENTS &  WORKSHOPS !

 

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Congratulations to 

Jeff D'Aigle VE3VLT,

who has recently become our 

Second Vice President 

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The Toronto Marine Amateur Radio Club

Phone:  416 486 6025  

Fax:  416 486 0417

Email:  ve3cfl@rac.ca

 

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