VHF Radio Tips
Easy VHF Radio Checks
Use these tips to make sure your VHF radio operates correctly prior to venturing out on the water.
The time to find out if your VHF radio is working is before you leave the dock. In the absence of a pro, you can perform a health check on the radio to confirm that it’s fit for sea duty.
The following are some simple tips to help you accomplish just that.
There are two types of tests that should be performed, an installation check and an operational check. Both can be done in minutes. A professional installation check is suggested once a year, preferably at the beginning of each boating season.
Check for any voltage drop, which can rob your radio of performance. Measure the voltage at the terminals where the VHF connects to the 12-volt system near the helm, while a helper keys the transmit button on the microphone to load the circuit.
The closer the reading is to 12 volts, the better — it may even be a few 10ths higher; any reading below nine volts requires servicing the circuit. (A voltmeter can be purchased for as little as $20 at Radio Shack and is simple to use).
Look for any cracks, which can lead to water intrusion, appearing along the antenna’s length. Identify and correct any sharp bends or crushed sections of the antenna cable, since these can reduce transmission power.
The antenna connector at the back of the radio is a frequent cause of radio failure. Confirm that it is free from corrosion and without tension from a tightly stretched antenna cable.
If you can get on the air to ‘radiocheck’ with another boat or base station at a reasonable distance away (not from a nearby boat on the same dock), you can rest assured the VHF is ready for duty. But if no one is available for a live radio check, you need to check the radio’s three key operating functions: transmission, modulation and reception.
One trick to see if your radio is transmitting is to keep an eye on the ammeter function of your test meter. If your boat is equipped with an ammeter, you can use that too, though most boats aren’t equipped with this helpful gauge.
In the receive mode, your radio should read around one amp of current. When you transmit on high power, the ammeter should kick up to about five or more amps. This is a fair indication that the radio is transmitting at full power.
Confirm your radio’s “hearing ability” by tuning to a 24-hour weather broadcast station that is 25 or more miles away. Reception indicates your receiver is probably OK. Alternatively, tune to a local weather channel, remove the antenna cable from the radio and touch the tip of a narrow screwdriver blade or car key to the center conductor of the radio’s antenna connector.
If you can hear a local weather station with such a tiny antenna, the radio should be receiving properly. Warning: Do not key the mic while the antenna is disconnected or you’ll fry your set.
You may be transmitting 25 watts of power, but if your voice doesn’t “modulate,” or vary the radio’s signal, no one will hear your message. A quick test is to switch to one watt, or low power, and monitor yourself on a handheld. You may have to turn the volume down or have someone take the portable VHF down the dock to prevent “squealing” due to signal overload. If your voice is understood, the radio is modulating OK.
Handy Radio Check Meter
One of my favorite means to test a VHF is Shakespeare’s ART-3 radio/antenna tester ($125). It’s palm-size and can easily be connected between a VHF and antenna as a kind of “stethoscope” to monitor and indicate the radio’s power output and the efficiency of the antenna and to evaluate reception as well.
The ART-3 will give you a radio check every time you use the radio!
If the radio starts to have problems when you’re away from the dock, here are a couple of curative tips you can use to help remedy the situation.
If the radio doesn’t transmit or you get reports from nearby boaters that they can’t hear you or that you are cutting in and out, the microphone cable may be at fault. While listening on a handheld VHF, stretch and manipulate the mike cable to see if you can pinpoint an intermittent wire in the cable.
If found, twist or fold the cable to find a position where the microphone will work and then wrap electrical tape or a zip tie around the cable to maintain that position.
Antenna and Cable Cure:
If you can make contact only with nearby boats, you may have an antenna or cable problem. Keep a backup antenna stowed on board as insurance. A short sailboat antenna will do with an appropriate length of coaxial cable. You can temporarily secure the antenna to a side rail with tape or an antenna rail mount to get you operational.
Radio failure due to loss of voltage is common. Know where the in-line fuse is located and keep spare fuses handy. Loose connections and corrosion can cause radio failure. Cleaning and tightening the radio’s power cable connections can often restore normal operation.
Article courtesy of Ken Englert