Praxinoscope
Well-Known Member
Bought one years ago, took it out of its container once to check it, since then it has lived in a locker, it's one of those things like liferafts, flares etc. that you buy but hope you don't have to use.
Emergency VHF antennae
- Thread starter laika
- Start date
Bru
Well-Known Member
Those who are blithely relying upon a hand held VHF as their sole backup in case of antenna failure may find themselves in a pickle one day
The range on a handheld, even a good one, is limited
I have a Glomex emergency antenna, bought for previous boat, for that very reason (having experienced masthead antenna failure just when i didn't need it and discovering that i couldn't reach the Coastguard on a 5w hand held even though i was only a couple of miles offshore) although current fine vessel has two masts and two Metz antennas one on each!
Even just wedged under the sprayhood, the Glomex connected to the main VHF outperforms my SH top of the range hand held by a country mile. It performs so well, in fact, that it saw a yacht i lent it to all the way to and from the Solent and throughout the RTIR
Although it's now unlikely I'd ever need it, it's going nowhere!
The range on a handheld, even a good one, is limited
I have a Glomex emergency antenna, bought for previous boat, for that very reason (having experienced masthead antenna failure just when i didn't need it and discovering that i couldn't reach the Coastguard on a 5w hand held even though i was only a couple of miles offshore) although current fine vessel has two masts and two Metz antennas one on each!
Even just wedged under the sprayhood, the Glomex connected to the main VHF outperforms my SH top of the range hand held by a country mile. It performs so well, in fact, that it saw a yacht i lent it to all the way to and from the Solent and throughout the RTIR
Although it's now unlikely I'd ever need it, it's going nowhere!
TernVI
Well-Known Member
The plug may be plated with something incompatible like chromium.
The braid may have tarnished, in which case the loss of the cable may be high.
Most decent coax connectors clamp the braid rather than soldering it.
You may need to scrape off the chrome or other coating.
Better flux may help. I often use the stuff which comes in a marker pen.
Are you using lead free solder?
Is the iron hot enough?
I would have suggested buying a BNC-PL259 adaptor.
laika
Well-Known Member
Crimpers for coax seem to start about £20 but no idea how good they'd be: I soldered mine and at the time was thinking they were something I'd need once every 15 years. I would have thought it was the ideal type of tool for a yacht club to own. In fact a refusal to consider buying then renting out for a small fee rarely used but occasionally essential tools was one of the reasons I realised the club I was briefly a member of was not for me.
Daverw
Well-Known Member
Crimping the coax is better than trying to solder the braid, I still solder the centre pin even if it can be crimped though. The issue with crimps is that their are a number of sizes each with a different crimp size, I have 5 different tools but as I use them often for Ham gear it’s not a problem, it’s not really possible to crimp without the correct tool
Gerry
Well-Known Member
Talking to an ex air sea rescue pilot I asked what, in his opinion, was the best bit of kit to carry for emergency use. he said an emergency VHF aerial. We went out and bought one the following week. For some 10years it moved from one end of the locker to another as we tut tutted about the cost and space for something we never used.....then. We were hit by lightning in an isolated lagoon in Belize and lost all our instruments. It gave us a much needed ability to assure friends we were ok and the knowledge we could get help if needed as we made our way pretty much blind to Guatemala. As I recall it was simple to use and very effective. It's back in the locker again-still being moved on a regular basis but we no longer tut tut at it!
greeny
Well-Known Member
rogerthebodger
Well-Known Member
As I quoted above I made an emergency vhf antenna and some king of emergency is desirable.
On top of he home made aerial I have a second fixed vf with its own fixed arial together with a seperate AIS aerial which could be used in an emergency.
I also have 2 handhelds, one that can be connected to one of my permanent aerial
On top of he home made aerial I have a second fixed vf with its own fixed arial together with a seperate AIS aerial which could be used in an emergency.
I also have 2 handhelds, one that can be connected to one of my permanent aerial
Buck Turgidson
Well-Known Member
I'm an ex-SAR pilot. He's wrong. An epirb will put the aircraft within HH vhf range. Homing onto a VHF voice signal is so last century.
Gerry
Well-Known Member
Actually it was last century!
Graham_Wright
Well-Known Member
I’ve just bought a coax changeover switch in naïveté for the wrong reasons (see post). But it would be fine for this application.
laika
Well-Known Member
Thanks for everyone's input. Not being able to decide between the commercial offerings I decided to defer the decision and for my project construct a DIY dipole antenna using some coax, a pl-259 connector a couple of other bits of wire and a soldering iron. I didn't need particularly good reception: I was investigating an issue someone was having sending data to marinetraffic and had acquired a dAISy HAT to experiment with but as I only have a narrow view of the thames from my 1st floor balcony (surrounding buildings are taller than that) I was really only expecting to pick up boats passing that narrow gap. As it happens I seem to be picking up boats the other side of blackfriars bridge 6km away.
My DIY antenna isn't robust enough to be good "emergency antenna" but it's been a good learning experience. Moreover having always been more Jobs than Wozinak in my sartorial sensibilities I've never really understood the computer geek stereotype. Having watched a bunch of youtube videos on antenna construction by socially awkward men with excess facial hair and bad fashion sense I suspect the general public are confusing computer geeks with radio geeks.
My DIY antenna isn't robust enough to be good "emergency antenna" but it's been a good learning experience. Moreover having always been more Jobs than Wozinak in my sartorial sensibilities I've never really understood the computer geek stereotype. Having watched a bunch of youtube videos on antenna construction by socially awkward men with excess facial hair and bad fashion sense I suspect the general public are confusing computer geeks with radio geeks.
Plum
Well-Known Member
I too made my own AIS receiving aerial from a length of coax and reliably pick up ships at 8 to 10nm and small boats 4 to 5nm. Aerial is 2m above waterline. However, I would not risk a diy aerial to transmit from my vhf radio even as an emergency aerial.
www.solocoastalsailing.co.uk
Bru
Well-Known Member
That's pants! With an AIS tuned Metz Manta atop the mizzen i reliably pick up shipping out to 40 to 50 miles and small craft at 10 to 20
I'm sorry, I'm extracting the Michael a bit there .. and showing off!
At 2m above the waterline that's not bad at all by any standards let alone DIY twig standards