YachtCom - Marine SSB antennas | backstay antennas | SSB ground | Dynaplates | HF Whip antennas

Marine MF/HF system

This page should give you a guide on installing an MF/HF (SSB) transceiver on a average size yacht.

M802 system overview



MF/HF (SSB) Installation: Getting it right!!!

There are 3 main parts to an marine MF/HF installation:
  1. The Power Supply
    An MF/HF (SSB) transceiver requires peak currents of 25 to 35 Amps, depending on transceiver and power output. Hence the voltage drop between the power source and the SSB transceiver should be no more than half a volt.
  2. Good ground
    For any MF/HF radio system to work a good connection to ground or salt water is required. On a steel yacht this is not a problem. On a plastic yacht you need to mount one or more 300mm by 75mm ground plates to the outside hull of the yacht and connect them to the ATU with 50 mm by 0.5 mm copper strip.
    Keep the antenna grounding system completely separate from the DC or electrical grounding system.
    Inside the hull internal grounding such as wire mesh or inductive paint and KISS-SSB do not work well on low frequencies, as they can induce RF current into the boats electrical systems.
  3. The Antenna
    The antenna MUST be kept clear of other cables and electronic equipment.
    The start of the antenna is at the ATU, so mount the ATU well clear of other electrical equipment and cables.
    A 7 metre long marine whip antenna works best as it gives vertical polarization which is good for long range communications on higher frequencies, 8MHz and above depending on the whip length. The backstay can be used if properly insulated and a good RF connection is made. Due to the length of the backstay, performance is usually better than a whip on the lower frequencies, 2 MHz and 4 MHz.
    Try and keep the antenna well clear of any metal, including bottom section of backstay.
    The ATU can produce some very high RF voltage which can cause burning if touched. It is therefore highly recommend that an high voltage weatherproof single core cable is used between the ATU and the antenna such as GTO-15.

Marine MF/HF (SSB) antennas

Whichever antenna you are going to use, backstay or whip, this page is intended to give some hints on how to get the best performance.

First thing to consider is that your SSB antenna is like a musical instrument, if you want to sound good (transmit well) then you must get it right. Although it may receive stations does not mean that it will transmit or radiate well.

The antenna starts at the top of the ATU (antenna tuner unit) and ends at the top of the antenna, if using the back stay then top insulator. Therefore the cable from the ATU to the antenna itself is part of the antenna and it is recommended that a high voltage cable is used. It is not practical to get an antenna system on a yacht to work across a wide range of wavelengths. An MF/HF SSB works on a wide range of frequencies (2 MHz to 25 MHz) and therefore wavelengths are between 12 metres to 150 metres.

An antenna which works on 12MHz may not be so good on 2 MHz.
A good antenna on 2 MHz is harder to achieve due to the long wavelength of 150 metres but may not be effective on 12MHz due the multiple wavelength of 6 wavelengths.
When considering the antenna system, decide what frequency you are going to use the most and optimize the antenna for that frequency.

Avoid multiple wavelengths or half wavelengths as the ATU may have problems tuning to these frequencies.
If the antenna length is 15 metres long then the ATU should tune across a frequency range of 1.6 to 25 MHz with no problems.

NOTE: The antenna on an SSB systems starts at the Antenna Tuner Unit (ATU) !

Yacht Communications



Insulated Backstay Antenna for Yachts.

The backstay can be used as an antenna, if properly insulated and a good RF connection is made to it.
Due to the length of the backstay, performance is usually better than a whip on the lower frequencies (2 MHz and 4 MHz).
Try and keep the antenna well clear of any metal, including bottom section of backstay.
  1. Mount top insulator at least 1 metre or more from top of mast.
  2. Mount bottom insulator close to deck level.
  3. The antenna length, from top of ATU to the top insulator, should be no shorter than 7 metres and no longer than 15 metres.
    1. To avoid half wavelengths on marine frequencies, the antenna length should be no longer than 15 metres.
    2. If antenna longer than 15 metres then ATU may have problems tuning the antenna on higher frequencies.
  4. Stand the antenna cable from the antenna tuner to the backstay off uninsulated backstay or other metal by 75 mm using some plastic tubing and secure with cable ties.
    1. Keep antenna as far away from other cables and metal objects as possible.
  5. Use a high voltage weatherproof single core cable between the ATU and the antenna, such as GTO-15.

NOTE: The antenna starts at the ATU and therefore the antenna is between the ATU and TOP insulator of the backstay!





Bottom Section of Backstay

BackstayInsulated Backstay, if done properly a backstay can make a very good SSB antenna.
Connection to backstay:
The weakest electric link in any backstay insulation, is the connection to the backstay.
Keep the connection clean and do look from time to time for corrosion.

Depending on the frequency, you may loose transmit power if you do not stand off the antenna cable from the bottom backstay section.

It is highly recommend that an high voltage weatherproof single core cable is used between the ATU and the antenna, such as GTO-15.

NOTE: The antenna starts at the ATU and therefore the antenna is between the ATU and TOP insulator of the backstay!

Yacht Communications


Standing antenna cable off the bottom of the backstay
BACKSTAY


See what happens if you touch the antenna when transmitting 100 watts!


Dynaplates

A good antenna system requires a good ground, on a yacht this means having a good connection to salt water. On the fiberglass yacht this is achieved by fitting 1 or 2 ground plates to the outside of the hull which is always under the water line.

A good quality Dynaplate should be used, good quality Dynaplates have lots of small holes in them allowing sea water to seep into them increasing the suffice area and therefore giving good contact with sea water.

To reduce drag the Dynaplate should be mounted flush to the outside hull of the boat with no gaps showing else weed and small animals get caught in the gap which can increase drag on the yacht.

The Dynaplate should then be connected to the antenna tuner unit (ATU) by means of 50 mm copper or wider strip copper strip. The length of the copper strip should be kept as short as possible. To reduce possible RF earth loops, the Dynaplate should NOT be connected to any other part of the SSB or boat electrical system.

dynaplates

Click here to order your Dynaplate

RYA RADAR course for yachtsmen
All you need to know about radar

http://www.yachtcom.co.uk/ryaradar

How to get in touch:

Leave us a message - click here!
Send email - click here!
by phone 01489 565100

KISS-SSB Counterpoise HF Radio Grounding System

The KISS-SSB grounding system works on all frequencies from 2 MHz through to 30 MHz with an SWR of 1.2 or less and works just as good or better as the copper foil/bonding system.

It comprises of a 119 cms lead that attaches to the "grounding lug" on your tuner (ATU) and then you just stretch out the remaining 3 metres long tube inside the hull of the boat. It is that easy to install:
  1. No drag when sailing.
  2. No need to drill holes in the hull under the waterline for a "grounding plate"
  3. No need to run the copper foil everywhere.
  4. No need to bond all the thru-hulls.
  5. Maintenance free.
  6. Can even be used when your boat is on the hard and not in the water.
  7. Helps save your expensive radio gear in the case of a lightning strike, as there is not a direct connection to water.

Keep the KISS-SSB system clear of other cables and electrical systems, as these can cause interference to the KISS-SSB system.
The KISS-SSB is only connected to the ATU and not to any other part of the SSB system or yacht's electrical system.




Click here to order your KISS-SSB grounding system

Keep it simple

Around the Internet you will find many ways of installing an SSB, what works on one boat may not work so well on another, the best advice is keep it simple (KISS)!

Click here to order marine HF antennas, grounding systems and accessories

RYA RADAR course for yachtsmen
All you need to know about radar
RYA Radar
http://www.yachtcom.co.uk/ryaradar

How to get in touch:

Leave us a message - click here!
Send email - click here!
by phone 01489 565100

Training

GMDSS Radio
RYA Radar

Equipment

SSB Radios
Pactor modems

Information

Legal Requirements
Installation

Tracking

Position Reportingl
Blogs


We are on Social Media:

© 2018 YachtCom. All rights reserved | Design by Bob Smith