Whats the best way to test my VHF

Matata

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I'm in the process of refitting a new ariel cable etc ( thanks Salty!). I hear lots of people pestering the Coast Guard for a "radio check". As I understand it the coast guard have VHF repeaters all along the coast so infact your VHF check is not really a great test of range and clarity. Whats the committee suggestions to do a good radio check? Nik
 

ProDave

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If you are fitting new cables etc, then you really should be checking the SWR with a meter to ensure all connections are done properly (they weren't by the previous owner of my boat)

If you get a good swr, then there's not much likely to be wrong, and a radio check just confirms the radio itself is working.
 

PetiteFleur

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If you are fitting new cables etc, then you really should be checking the SWR with a meter to ensure all connections are done properly (they weren't by the previous owner of my boat)

If you get a good swr, then there's not much likely to be wrong, and a radio check just confirms the radio itself is working.

I've also just fitted new aerial & cable(Salty John again!) - how do you use a SWR meter - are they easily available and to use/interpret? Mast is down at the moment.
 

30boat

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I've also just fitted new aerial & cable(Salty John again!) - how do you use a SWR meter - are they easily available and to use/interpret? Mast is down at the moment.
This is for CB but the procedure is he same

CB/Ham Field-Strength SWR Meter
(210-0533) Operation Faxback Doc. # 47578

INTRODUCTION

The meter's field strength function helps you position your antenna for
the best coverage and determine the effectiveness of changes you make to
your antenna, antenna cable, and transmitter.

Carefully read all of these instructions to get the best use from this
meter.

WARNING: You can use this meter to make measurements on equipment that
uses high voltages. Carefully observe all safety precautions
provided with the equipment you are testing.

Note: You need a separate 50-ohm coaxial cable (such as RG-58U) with a
PL-259 connector connected to both ends (such as Cat. No. 278-0968,
not supplied), long enough to reach from your radio's antenna jack
to the back of the meter.

MEASURING SWR

Measuring SWR shows you how much of your radio's transmit power is
reflected from the antenna back into the antenna cable, generating heat
and wasting power. With this information, you can adjust the length of
your antenna or antenna cable so your antenna and radio combination can
produce the maximum power they are capable of producing.

For more information about measuring SWR, see the ARRL Handbook, available
at your local library.

CONNECTING THE METER

To connect this meter to your CB or amateur radio and your antenna, you
need RG-58U coaxial cable (not supplied) with a PL-259 connector on both
ends (such as RadioShack Cat. No. 278-968). The cable must reach from
the back of the meter to your radio's antenna jack.

Follow these steps to connect the meter to your radio and antenna.

1. Turn off your radio. Then disconnect the antenna from the radio and
plug it into ANTENNA on the back of the meter.

2. Plug the coaxial cable into the radio's antenna jack and into
TRANSMITTER on the back of the meter.

CALIBRATING THE METER/MEASURING SWR

1. Set CALIBRATION/FS/SWR on the front of the meter to CALIBRATION/FS.

2. Turn on your radio. Then select a channel or frequency on your
transmitter and hold down its transmit key. Do not speak into the
microphone.

Notes: An SWR reading will be different for different frequencies
(channels). If you transmit on one channel more often then
any other, select that channel. If you transmit on several
channels, choose a frequency in the middle of the range of
channels you use. (For example, if you transmit on all 40 CB
channels, choose Channel 20, because it is midway between
Channel 1 and Channel 40.)

If you use a CB that has sideboard modes (SSB), do not select
any of these modes. (Use only AM for SWR measurements).

If you have an amateur radio, select the continuous wave (CW)
or tuning mode to check the SWR.

3. While you hold down the transmit key, rotate the meter's knob until
the needle points to CAL.

4. Release the transmit key, then set CALIBRATION/FS/SWR to SWR.

5. Press the transmit key again, then read the SWR by noting the needle's
position on the upper SWR scale. A meter reading of 1 on the upper
scale is ideal.

The figure shown between the upper and lower scales on the meter
(% REF POWER) indicates the percentage of power that is wasted
through reflection of the signal from the antenna back into the
antenna cable. For example, an SWR reading of 1.5 also means that 4%
of your signal power is lost. However, 96% of the radio power is more
than enough for almost all applications.

6. Repeat Steps 1-5 for each channel or frequency you want to get an SWR
reading for.

Interpreting SWR Readings

An ideal SWR reading is 1.0, but this reading is usually possible only
under laboratory conditions or with a dummy load. Actual antenna
installations have higher readings. The information below will help you
interpret the readings you get.

SWR Efficiency Interpretation

1.0 to 1.5 Excellent The antenna cable and the antenna length
match the transmitter's output
requirements almost perfectly.

1.5 to 2.0 Very good The antenna, the cable, and the
transmitter operate very efficiently.

2.0 to 3.0 Acceptable The antenna, the cable, and the
transmitter operate with some loss. If
possible, adjust your antenna or antenna
mounting system to improve.

Above 3.0 Inefficient Adjust your antenna or antenna mounting
system to improve efficiency.

IMPROVING SWR

There are several ways to improve the SWR of your radio/antenna
combination. Try these first.

Be sure you are using the type of cable recommended for your
equipment. If the manufacturer recommends a 50-ohm cable, do not
substitute another type that has a different impedance.

Confirm that you mounted your antenna according to the manufacturer's
instructions. The angle and the base arrangement can affect the SWR
reading.

Adjust the length of your antenna according to the instructions
provided by the manufacturer. A change of as little as 1/8 inch can
make a measurable difference.

See your radio's and antenna's owner's manuals.
 

Playtime

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Of course I have an SWR meter because I have been a radio ham for over 30 years. But well worth buying for peace of mind, or ask at your boat club if anyone has one, or contact your local amateur radio club and someone may help you.

Can you recommend a suitable, reasonably priced item. They range in price on eBay from less than £10 to more than £200. :confused:

The one identified by 30boat above appears to be CB/HF (3-30MHz). Presumably we need VHF (around 156.8 MHz)?
 

ProDave

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Salty John

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Whats the committee suggestions to do a good radio check? Nik

As Ken says, try contacting a marina or another boat a reasonable distance from you.

When you install new connectors on your cable make sure there is no short between the centre pin and the body of the connector. Check with a multimeter. Do this with both the radio and the antenna disconnected or you'll just see a dead short. If you're happy the connectors are good, and you have no reason to believe your cable is compromised, listen out for traffic. If that all works try transmitting. Simple really.
 

VicS

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Whats the best way to test your VHF ?

Call the coast guard for a radiocheck ! But do it when they are not busy!
 

john_morris_uk

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I know that on HF the SWR can change considerably depending on the frequency you are using, does it matter as much on VHF? Just a thought for those testing on channels other than 16 .....
The VSWR into any half decent Marine VHF antenna shouldn't change appreciably across the frequency range of the channels of the Marine VHF. Don't worry about it.
 
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FullCircle

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I have just bought an Avair AV-201, which go on ebay for around 30-35 quid, or 55 quid new.
It covers the Marine VHF range in the 156Mhz band.
The band is settable too, from the 2m HF to 180Mhz VHF
This has 2 settings for output power that I will use. A lot od SWR meters have settings for 200w and 1Kw. Not a lot of use on 25w max power from your VHF. So mine has 5w and 20w, although the 20w setting works on hi power from my VHF.
The manual is childs play, and it fdoes not actually need external power of any sort, although you can plug it into 12v for instrument lighting and LED operating lights.

I also bought the patch lead required from ebay new for a fiver. (goes from the VHF to the SWR meter).

On my previous setup I could regularly pickup Oostende Radio, 90 miles away, but I have changed the antenna, as the old one had rotted out.
 

FistralG

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The best advice I read was to get a handheld VHF, send the crew off in the tender into the wide blue yonder, transmitting and receiving to you, on the boat, at regular intervals. When the quality of the transmissions diminishes to an unacceptable level they can then return. You can judge the performance of your radio based on the distance they cover.
It would be safe to assume that would be the minimum range as most boat radios and definitely shore based radios would have antenae higher and with better performance than a handheld.
 
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