Can anyone help me with the following problem? I have a new Midland "Neptune" VHF/DSC radio and being a long way from the sea I would like to practise using it without transmitting, which is illegal unless safety at sea is involved. I could do this with a dummy aerial, which is just a passive device of electronic components mimicking the real aerial's load on the transmitter, that way I would not damage the output or send illegal transmissions. I am an electronics engineer, but not in telecommunications, so could easily build a dummy load against suitable circuit. Conversely on the recent RYA training course I attended two radios 9 apparently modified for training purposes) were connected by a length of coax cable into their respective aerial sockets, so that we could practise without transmitting through the ether. Can anyone offer a similar link from say my present radio to a hand held?
The radio will be fitted in a friend's yacht in Greece later this year, hence I would like to get familiar with it.
I would appreciate any help or advice on who to contact for assistance with this problem.

I am not familiar with chat rooms so I hope that i am sending this request correctly.

Steve,
You can, by the way, buy a simulator for about £20 to practice on your computer. Here are 2 links for example:
http://www.lightmaster.co.uk/dscsim.htm
and
http://www.sailgb.com/p/vhf_dsc_radio_simulator/
I used a simulator for my DSC radio licence, if that is any encouragement. The whole process of learning and being examined took about an hour. It is not a big deal, there isn't much to get familiar with.

Hello Graham. Thanks for responding, I have got the Lightmaster simulator, which I did find useful prior to taking the VHF exam, although it is a bit tedious to use and it's a pity they don't provide a microphone to plug into the p.c. and allow real simulation. My concern is to get familair specifically with the new radio prior to fitting and also so that the other 4 owners can do so too, without causing damage to it. I know that they all have similar knobs and whistles but each manufacturer has there own system of entering information.

If you know anyone who has the same model, probably ask them if youcan go out for a days sailing with them to have ago.

Go into a lead room so it would confine the signal maybe? I'm no engineer, but I will see if I can get any advice from the makers for you.

Thanks Roxy, I have e mailed the maker's UK representatives but have not yet had a response.

How about using some 446 radio's as then you wouldn't be in breach of any code.

What are 446 radios?
For anyone interested here is the advice i rceived from a fellow memeber of my institute and which i am gfolowing. I will let you know how things go. Rgds. Steve:- QUOTED INFO., AS FOLLOWS:-
You are correct to suggest using a dummy load, I certainly would strongly reccommend that you do not connect the two transceiver aerial connectors together, as switching one to transmit will inject a considerable amount of power into the receiver input first stage of the other transceiver. Receiver input stages are designed to to detect very weak signals and there is a risk that it would be damaged by that level of power

I suspect that the radios that were connected together on the course you attended, had a substantial attenuator in series with the coaxial cable to reduce the transmitted power to a safe level before it was fed to the other transceiver . In my experience I would be unhappy about doing this, preferring to use the following method which effectively isolates the two radios.

I suggest you try the following which effectively uses two dummy loads, one for each transceiver, enclosed in a metal container which will reduce any radiated signal to a miniscule amount. Theoretically, there should be no radiated signal, but anyone like myself who has worked with radio frequencies (RF)for years, knows that RF has a nasty habit of escaping (and getting into) even the best of screened enclosures

Try this:- obtain a small metal enclosure such as a small can or die cast box, mount two coaxial connectors on it for linking to the two transceivers. Inside the box mount two 50 ohm resistors. I am presuming 50 ohms is the impedance of the output of both transceivers.(Comment from Steve, most aerials appear to be 50 ohms impedance) The resistors should (ideally) be a non inductive type as this reduces radiation, however as I am assuming the transmitted power is low and as they are mounted in a screened box, it is not essential. Ensure the resistor power rating is higher than the power rating of the transmitter and check the resistor spec to see if this power rating is with or without a heat sink.If it does need a heat sink, the enclosure may be sufficient and you could bolt the resistors to this. Some resistors are available that are designed for easy fixing to a heat sink. Connect one resistor across one coaxial connector and the other resistor across the other connector keeping the resistor wires as short as possible then seal the enclosure. Each transceiver is therefore connected to an adequate matched dummy load in a sealed metal container preventing radiation of signal. There should be sufficient signal leakage from the transmitting resistor to the receiving resistor to activate the receiver without damaging the receiver first stage.

I hope this advice from an old electronics/telecoms engineer and Licensed radio amateur (since about 1966) is helpful.
END

Like walkie takies, though I know you want to use your radio not just practice VHF.

Most of the mayjoy stockist should have working dummies if you know what I mean. WHy not ask it you can play with the display modle a bit?

Your other info was really intresting to read. Thanks for posting it.

446 radios are completely incorrect frequency to marine VHF. which goes from approx., 156Mhz to 162MHz.

Still good for paracticing the lingo though

Did his advice work Steve?

Hello pirate. So far so good, I am borrowing a second radio to confirm, will let you know.Have found out that unless the radio is receiving some of the facilities will not respond as per., the instruction book, as per., usual it is not what the manuals tell you but what they don't which is most important. The UK agent, Allan's, is quite helpful though, considering that I didn't buy it from them. The original supplier said that they only sell 'em they don't know anything about 'em. Is it vital to have had a lobotomy prior to being a manual writer?

If it is to constuct a flat pack or control anything electrical - yes a labotomy is essential.

Sound like a tipical supplier - always shifting from the blame. 'Of course' they don't know anything about after they have sold it too you!

I took the RYA DSC certificate last month. We used software simulators for most of the course and there were two vhf's with dummy loads in a box, similar to that described by Steve, so that we could all try with real DSC radios.

Have you managed to put it to use at sae yet chris?

Hi Roxy. No I have only a VHF at the moment but I thought I had better get a DSC operators licence so I can use or buy a DSC when the time comes for a replacement.

I took my VHF cert at the Merchant Navy college Greenhithe in 1982. In those days before mobile phones we had to use vhf to make link phone calls via coast radio stations and were required to carry a 257 page "Handbook for Radio Operators" on board.

Not very good if you are trying to conserve weight for racing! Sounds a little long winded. Well done on gaining the qualification though. It's a good one to have