45m
New Member
Want to check that the masthead light and VHF aerial are working before I step the mast on my new (to me) 27' yacht. Is there an easy way to do this while the mast is lying on the deck??
Susie
Susie
How to check masthead light and VHF aerial
- Thread starter 45m
- Start date
cmedsailor
Well-Known Member
????????? Turn them on and have a look..... unless I didn't understand your question!!
45m
New Member
If it was that easy I wouldn't have asked ;-) the bottom of the mast is 20' away from the mast step and the other end of the cables!! want to check that they work before I go to the crane to lift the mast back into place....
VicS
Well-Known Member
Check the light with a multimeter on its lowest ohms range. A 25watt bulb will have a resistance less than 1/2 ohm. It would be nice to check with a battery but it'll be all to easy to short it out. Clean the bulb contacts and and those in the holder. Apply a very thin film of vaseline or silicone grease.
Not so easy to check the aerial though. It'll probably read vitually zero ohms between the centre conductor and the outer. In fact suspect something wrong if it doesn't.
Not so easy to check the aerial though. It'll probably read vitually zero ohms between the centre conductor and the outer. In fact suspect something wrong if it doesn't.
lenseman
Well-Known Member
- Joined
- 3 Jun 2006
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- South East Coast - United Kingdom
Hi Susie - welcome to ybw forum
To check the lights, you will need to know what voltage they require (almost certainly 12 volts BUT be careful they might need a lower or a higher voltage - LED lighting) and then connect a car battery via a suitable lead (car jump leads will do) to the 'tail' of the wires that are on the mast going to the lights. All you then have to do is to walk to the pointy end and see if they are working /forums/images/graemlins/smile.gif
The VHF antenna is slightly more difficult. Best thing to do is to look very carefully at all the parts of the masthead antenna and carefully inspect any cracks or damage to the antenna base and any cuts or damage to the co-axial antenna cable.
If all seems ok and unbroken then repeat at the base or your mast. If there has been any break which might have allowed water to penetrate into the cable or antenna base then treat the set up as suspect /forums/images/graemlins/frown.gif
To do a more full inspection requires a special meter called a SWR meter. This stands for Standing Wave Ratio (meter) and when connected correctly between the antenna and a suitable marine radio (transmitter), shows the forward and reverse power (wattage) that is going up to into the antenna and it also shows how much of that power is reflected back again towards the transmitter. The less reflected, the better /forums/images/graemlins/smile.gif
You don't give a location in the world as to where you are located but I am sure you should find a person in your local marina with the necessary knowledge and or equipment? /forums/images/graemlins/cool.gif
Come back to me if you need more help
David
To check the lights, you will need to know what voltage they require (almost certainly 12 volts BUT be careful they might need a lower or a higher voltage - LED lighting) and then connect a car battery via a suitable lead (car jump leads will do) to the 'tail' of the wires that are on the mast going to the lights. All you then have to do is to walk to the pointy end and see if they are working /forums/images/graemlins/smile.gif
The VHF antenna is slightly more difficult. Best thing to do is to look very carefully at all the parts of the masthead antenna and carefully inspect any cracks or damage to the antenna base and any cuts or damage to the co-axial antenna cable.
If all seems ok and unbroken then repeat at the base or your mast. If there has been any break which might have allowed water to penetrate into the cable or antenna base then treat the set up as suspect /forums/images/graemlins/frown.gif
To do a more full inspection requires a special meter called a SWR meter. This stands for Standing Wave Ratio (meter) and when connected correctly between the antenna and a suitable marine radio (transmitter), shows the forward and reverse power (wattage) that is going up to into the antenna and it also shows how much of that power is reflected back again towards the transmitter. The less reflected, the better /forums/images/graemlins/smile.gif
You don't give a location in the world as to where you are located but I am sure you should find a person in your local marina with the necessary knowledge and or equipment? /forums/images/graemlins/cool.gif
Come back to me if you need more help
David
Cloven
Well-Known Member
Light are easy - just connect to a 12v battery & see if they work. As for the VHF, others more techy that I will have to answer that.
mikefleetwood
Well-Known Member
Further to VisS
When you check the bulb, it's worth checking again with the bulb removed, just to make sure there's no short circuit. Normal mulimeter might have difficulty telling cold 25W bulb from cable resistance (anything less than 1 Ohm is difficuly to measure accurately)!
Aerial could be difficult to check as it could show as either open or short circuit, depending on configuration. Careful visual inspection would probably be as reliable. Look for crushed or chafed cable, corroded joints and connectors.
Good luck!
When you check the bulb, it's worth checking again with the bulb removed, just to make sure there's no short circuit. Normal mulimeter might have difficulty telling cold 25W bulb from cable resistance (anything less than 1 Ohm is difficuly to measure accurately)!
Aerial could be difficult to check as it could show as either open or short circuit, depending on configuration. Careful visual inspection would probably be as reliable. Look for crushed or chafed cable, corroded joints and connectors.
Good luck!
MarkGrubb
Well-Known Member
When the mast is stepped do the lights plug into sockets on the deck? If so you could make up an extension cable that connects the deck sockets to the lights (or their plugs) If they work then you also know that all the boat wiring associated with the lights is fine (switches and internal wiring).
Again for the VHF, you could try making up an extension cable that reaches from the radio to the antenna, or necessary connector, and then try a radio check with a local marina or boat. The signal report may not be the best because the aerial is low down and horiztonal, instead of vertical (assuming its already fitted and the mast is lying on its side), but it will give you a good idea that things are OK. The best method is to buy an SWR meter mentioned by the previous post.
Keep all the cables for when you next unstep the mast.
Again for the VHF, you could try making up an extension cable that reaches from the radio to the antenna, or necessary connector, and then try a radio check with a local marina or boat. The signal report may not be the best because the aerial is low down and horiztonal, instead of vertical (assuming its already fitted and the mast is lying on its side), but it will give you a good idea that things are OK. The best method is to buy an SWR meter mentioned by the previous post.
Keep all the cables for when you next unstep the mast.
reginaldon
Well-Known Member
45M I've been trying to workout the same problem and I did come to the same conclusions
john_morris_uk
Well-Known Member
[ QUOTE ]
To do a more full inspection requires a special meter called a SWR meter. This stands for Standing Wave Ratio (meter) and when connected correctly between the antenna and a suitable marine radio (transmitter), shows the forward and reverse power (wattage) that is going up to into the antenna and it also shows how much of that power is reflected back again towards the transmitter. The less reflected, the better
[/ QUOTE ] An SWR meter is a good starting point. Unfortunately very lossy co-ax also gives a low standing wave ratio and can lead you into thinking all is well when it is not. However if the co-ax looks good, has no cuts or nicks in it and you are confident no water has got inside the outer sheathing, then a low SWR is the best indication that all is well. Look at the ends- unscrew the co-ax at the antenna end and see if it looks green and yucky. If it is clean and bright then probably all is well. Put some vaseline on the end before screwing it back together.
After that its a matter of trying it out on low power to local and not so local stations and perhaps comparing results with other proven installations. You will soon see if its working or not. If all looks OK, the chances are that it will be OK.
I won't get started on demytholigising the old wives tales about 'reflected power'... See my other posts on the subject and I will write out 100 times 'I must not get annoyed when people keep referring to reflected power!'
To do a more full inspection requires a special meter called a SWR meter. This stands for Standing Wave Ratio (meter) and when connected correctly between the antenna and a suitable marine radio (transmitter), shows the forward and reverse power (wattage) that is going up to into the antenna and it also shows how much of that power is reflected back again towards the transmitter. The less reflected, the better
[/ QUOTE ] An SWR meter is a good starting point. Unfortunately very lossy co-ax also gives a low standing wave ratio and can lead you into thinking all is well when it is not. However if the co-ax looks good, has no cuts or nicks in it and you are confident no water has got inside the outer sheathing, then a low SWR is the best indication that all is well. Look at the ends- unscrew the co-ax at the antenna end and see if it looks green and yucky. If it is clean and bright then probably all is well. Put some vaseline on the end before screwing it back together.
After that its a matter of trying it out on low power to local and not so local stations and perhaps comparing results with other proven installations. You will soon see if its working or not. If all looks OK, the chances are that it will be OK.
I won't get started on demytholigising the old wives tales about 'reflected power'... See my other posts on the subject and I will write out 100 times 'I must not get annoyed when people keep referring to reflected power!'
Spyro
Well-Known Member
If you have or know anyone who has one a Jumpstart pack is very handy for checking any 12 v items . As said previously connect it to the wires at the bottom of the mast for checking before stepping the mast.
jimi
Well-Known Member
... or even jumpleads from the car battery, I presume.
Re VHF, have you got a HH you can bung it on to try?
Re VHF, have you got a HH you can bung it on to try?
VicS
Well-Known Member
[ QUOTE ]
a Jumpstart pack
[/ QUOTE ] Yes but be careful messing about making connections to the wiring or the plug from such a unit or indeed any 12volt battery.
It may be only 12V but they can deliver several hundred amps if shorted.
An "extension lead" to reach from the deck socket is a better idea but just testing with a multimeter is a lot less trouble.
a Jumpstart pack
[/ QUOTE ] Yes but be careful messing about making connections to the wiring or the plug from such a unit or indeed any 12volt battery.
It may be only 12V but they can deliver several hundred amps if shorted.
An "extension lead" to reach from the deck socket is a better idea but just testing with a multimeter is a lot less trouble.
ghostlymoron
Well-Known Member
I would replace the bulbs as a precaution, it's much easier to do when the mast is down - keep the old bulbs as emergency spares.
Aerials are a bit of a mystery but you can easily check the continuity of the cabling (which is the bit most likely to cause problems) by disconnecting the aerial and pinching the inner and screening together then testing for continuity at the other end with a multimeter.
You could also make up an extension to the aerial cable using a suitable length of co-ax and a connector. If the radio then works OK. I have read that if the radio receives, it will also be working on transmit but I'm not sure this is 100% correct.
Aerials are a bit of a mystery but you can easily check the continuity of the cabling (which is the bit most likely to cause problems) by disconnecting the aerial and pinching the inner and screening together then testing for continuity at the other end with a multimeter.
You could also make up an extension to the aerial cable using a suitable length of co-ax and a connector. If the radio then works OK. I have read that if the radio receives, it will also be working on transmit but I'm not sure this is 100% correct.
noswellplease
Well-Known Member
If the mast is down I would take an opportunity to inspect the condition of the electrical connection to the light. Is it tarnished or or badly corroded, if so nip back wire another inch or so and reconnect. Soldering takes a bit of practice but if you remember that it flows downwards with gravity its not too difficult to make a good solder joint. Aerial may be a sealed connection but you can always bring along your VHF and connect up to a battery if you can get a suitable plug to fit your VHF. Call the local Coastguard station then for a test.
