Silva VHF radio - GPS connection help needed

[gilesfordcrush]

Hello all,

I have a Silva S15 VHF radio. It was getting it's GPS fix via an old Navman plotter - which has recently been removed as I work through upgrading the equipment. I now need to work out how I can get the GPS antenna feed into the VHF radio.

The connection on the rear of the radio is labelled as x3 wires to navtex (which I am leaving disconnected) x2 wires to an external speaker (which I don't have) and x2 wires to GPS (GND and GPS). The wire from my GPS antenna (mounted on the push pit) has two wires. In my ignorance I thought that these two would connect to the x2 wires for the back of the VHF set - but this does not work.

Does the GPS antenna need separate power? It would seem likely that it might? Or perhaps this radio needs the navtex to be working too?

I'm aware that the Silva radios are generally accepted to be a bit crap - but I'd rather get this GPS feed working, and plan to replace the radio next year.

Any help would be very welcome.

Giles
Moody 30. North Fambridge

 

[gilesfordcrush]

Also, is it possible/advisable to mount the GPS antenna at the masthead?

 

[snowbird30ds]

You say "gps antenna", if it's just an antenna and not a gps reciever it won't work, you need a gps reciever that will put out nmea sentences which is what your old plotter would have been sending out.

 

[pvb]

Was your GPS antenna supplied with the Navman plotter? Which plotter model was it?

GPS antennae should not be mounted at the masthead, but low-down.

 

[rosssavage]

There are two types of GPS antennae. One type actively resolves the GPS signal into NMEA sentences,, the other is passive and just passes raw GPS RF signals to the receiver.

Does it have co-ax cable? If so, it is raw RF signal and won't work with the radio.

If it doesn't have co-ax, but single multi strand wires (minimum of three, probably four, quite possibly more) then it might be able to output NMEA sentences and will require power. But you'll need to know the make and model of the antenna to determine the wiring.

Unfortunately I'll put money on it being passive (co-ax cable) and therefore not compatible.....

 

[gilesfordcrush]

Thanks for the replies. The signal cable is indeed co-axial. So I can conclude that the antenna is passive, which makes sense, certainly as far as how it was connected before - which was to the Navman Tracker 5505 plotter.

To be honest, I am rapidly forming the opinion that I should just ditch the entire VHF radio and GPS set up, and go for a Standard Horizon GX1700E GPS/DSC. The man at Cactus Nav thinks it will get the GPS fix within my boat, using the internal GPS receiver. For the time being I don't need a plotter, I'm still learning the ropes, and I have the iPhone Navionics app to keep me going.

I actually got a response from Silva - who advised me to ditch the VHF radio is it is old and likely to fail! At least they are honest.

 

[ex-Gladys]

Thanks for the replies. The signal cable is indeed co-axial. So I can conclude that the antenna is passive, which makes sense, certainly as far as how it was connected before - which was to the Navman Tracker 5505 plotter.

To be honest, I am rapidly forming the opinion that I should just ditch the entire VHF radio and GPS set up, and go for a Standard Horizon GX1700E GPS/DSC. The man at Cactus Nav thinks it will get the GPS fix within my boat, using the internal GPS receiver. For the time being I don't need a plotter, I'm still learning the ropes, and I have the iPhone Navionics app to keep me going.

I actually got a response from Silva - who advised me to ditch the VHF radio is it is old and likely to fail! At least they are honest.

The best thing you can do!!! I tried to help a mate with an S10, which was the biggest POS I've ever come across...

 

[bitbaltic]

Thanks for the replies. The signal cable is indeed co-axial. So I can conclude that the antenna is passive, which makes sense, certainly as far as how it was connected before - which was to the Navman Tracker 5505 plotter.

yes.

To be honest, I am rapidly forming the opinion that I should just ditch the entire VHF radio and GPS set up, and go for a Standard Horizon GX1700E GPS/DSC. The man at Cactus Nav thinks it will get the GPS fix within my boat, using the internal GPS receiver. For the time being I don't need a plotter, I'm still learning the ropes, and I have the iPhone Navionics app to keep me going.

I actually got a response from Silva - who advised me to ditch the VHF radio is it is old and likely to fail! At least they are honest.

I don't know why the radio would be likely to fail just because it is old- there are still plenty enough boats out there with working (basic) electronics like museum pieces. But as you will have to at least buy some form of GPS receiver to go between the antenna and the radio, you might as well go for a modern solution as you describe. I would also expect an internal GPS receiver to work no problems.

 

[PaulRainbow]

Ref the GPS working in the boat.

I have the following :

Garmin NMEA 2000 GPS, under the side deck in the aft cabin wardrobe.
USB GPS (laptop emergency), under the side deck in the main saloon.
Phone, variously located.
Tablet, also variously located.

All work fine. The Garmin GPS was temporarily located with the batteries, under a saloon sofa, still worked fine.

 

[lpdsn]

You've a few options I reckon.

You can get an NMEA 2K or 0183 intelligent antenna and feed it into the radio etc (they seem to be mainly N2K these days so you'd probably need a convertor too if the radio requires 0183).

You could get a GPS receiver that will use your existing antenna. Probably best getting an old one 2nd hand, although I'm quite happy with the 159i I bought. Suprisingly few non chart plotter options on the market these days.

Or as you say, you can go for the SH Gx2200. Not the cheapest option but I have to admit that my Gx2100 ranks pretty high on the value/price scale, so I'd be pro Standard Horizon.

 

[ShinyShoe]

For the time being I don't need a plotter, I'm still learning the ropes, and I have the iPhone Navionics app to keep me going.

Why don't you need a plotter if you are learning?
What is your backup plan if Navionic crashes, iPhone battery dies etc?
The Silva works. Yes it's a POS, designed I. The days when we all thought having snake on a mobile phone was verging on SciFi!

But...

Read the miab report from this week and you should think... "How resilient is my set up"?

How easy can you get a Long Lat on Navionic on iPhone? Can you do that while on the phone... even with a new VHF you can't be 110% sure it will never fail. Is the phone your backup plan, E.g. if you were dismasted...

On Navionics - Can you plot waypoints and navigate to them? (I.e. Bearing to next wot?) What if it crashes? What if it gets wet?


I'd have thought a <£50 second hand, handheld GPS with data and charge lead (Garmin 76¿) might be a half decent option. Interface to the silva. Has own internal battery so if something breaks on the silva you can read the long lat off and if you plan properly you can put key WPT in to navigate to. (Had the Humber Pilot done that with a HH unit he wouldn't have strayed into the shipping channel!)

When the Silva does die, replace with a unit of your choice then, but by then you may have bought a plotter. You will still have a cheap robust HH GPS in a locker when the 12V power does and you need a bit of help.

 

[chrishscorp]

When i bought my new to me boat she was fitted with an S15 the same as yours.
The boat needed rewiring which was done, the radio was supplied with GPS data from a 'mushroom' correctly mounted low down on the stern rail, i struggled to get the baud rates synced so it never did pick up a gps position even though it had previously through an ancient plotter.
It then decided to keep dropping the MMSI number from its memory then at the start of last season it just would not fire up.
It was replaced with an Icom M323G built into a side locker, it still picks up the satellite signal and so will find the GPS position even though it cant see the sky.

I would suggest a new radio with gps built in, the S15 is not very good !

 

[snowbird30ds]

I would go along with dumping the vhf and going the standard horizon route, I had a navman vhf (rebranded as other names too) that messed me about and gave me no confidence in vhf, since going SH I wouldn't touch a cheap vhf again, quality is worth paying for.
Why not go the extra and got one with ais built in.

 

[[70521]]

I would go along with dumping the vhf and going the standard horizon route.

+1

Simples.

 

[ghostlymoron]

As you have had a plotter, I would think it's likely you'll be fitting another eventually (I don't have one but I'm in the minority) so maybe your best bet would be to replace it - you'll then have all the options you previously had.
I've just bought a SH 1700e with built in GPS to replace a non DSC ICOM. Have yet to fit it but it is well reviewed.

 

[gilesfordcrush]

Thanks for the replies.

I don’t need a plotter for the time being, as I am unlikely to be leaving the River Crouch/River Roach/River Blackwater areas this year. I also want to learn traditional navigation skills. As far as a backup plan for communications, for the foreseeable future I’ll be in mobile phone contact, and every family member has a mobile (groan!). I do intend to sail singlehanded, and for that I will have a waterproof VHF hand-held radio, but all in good time, along with the plotter!

I’m going to keep the S15 for the time being, as it does work. I might even re-instate the old Navman plotter at the nav station, so I’ll get the GPS again. I’ll add a new VHF set to the shopping list for later in the year.

Thanks for all the help.

 

[prv]

I’m going to keep the S15 for the time being, as it does work.

Ok - so if you want a GPS position in it for DSC (of course, for your limited cruising area you might not care) there are loads of cheap GPS modules you can wire into it. The only complication is that most expect 5v power rather than 12v; the easiest way to arrange this nowadays is a USB adaptor intended for use in a car. Again, thousands of such things available for a couple of quid on eBay.

I recently bought one of these for a project:

http://www.ebay.co.uk/itm/Mini-Ublo...312422?hash=item25c0f8ac26:g:vqsAAOSwdzVXmlBH

Pete

 

[PaulRainbow]

Ok - so if you want a GPS position in it for DSC (of course, for your limited cruising area you might not care) there are loads of cheap GPS modules you can wire into it. The only complication is that most expect 5v power rather than 12v; the easiest way to arrange this nowadays is a USB adaptor intended for use in a car. Again, thousands of such things available for a couple of quid on eBay.

I recently bought one of these for a project:

http://www.ebay.co.uk/itm/Mini-Ublo...312422?hash=item25c0f8ac26:g:vqsAAOSwdzVXmlBH

Pete

What does that output Pete ?

 

[gilesfordcrush]

That is interesting - but as PaulRainbow asks, what signal is provided? Seeing as this looks like it is intended for use in Radio Controlled aircraft, I doubt it will output NMEA?

 

[nrcoyle]

That is interesting - but as PaulRainbow asks, what signal is provided? Seeing as this looks like it is intended for use in Radio Controlled aircraft, I doubt it will output NMEA?

Not 100% sure about that specific module, but in general with that style of unit for flight controller they are likely to, or be able to be configured to, output NMEA sentences. Bigger problem is that they will almost certainly output as UART so will need extra circuitry to flip the signal to suit a NMEA reciever.