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Mobile Internet

In this article I am going to describe how I set up mobile broadband internet on board nb Phoenix III.

MiFi – The travelling solution

For the last three years we have successfully used a Huwaei E585 MiFi dongle from ‘3’ on a monthly contract. I unlocked it sometime ago so not only has it given us mobile broadband in this country but we have been able to use it when travelling overseas too, with a locally bought sim card of course.


It’s a super bit of kit and I really can’t fault it except that in marginal reception areas it can often prove difficult to pick up a reliable signal so we usually resort to trying to find the best window to hang it in. Battery life after three years is not what it used to be so invariably the MiFi needs to be plugged into a power supply, not great if the best window is not near an outlet.

On the domestic front

We live in a house most of the time and until recently had a fixed telephone line which gave us broadband at home. We came to the conclusion that the line was very rarely used for telephone calls and so I started to think about rationalisation, after all, we had a mobile broadband contract and we only ever needed one connection. On the very rare occasion that we were in different places  to each other, smartphone internet access is good enough. The MiFi was the first solution that I tried at home but I found that after extended use plugged in, the device froze and had to be restarted by removing and replacing the battery. It was no more than an inconvenience but it prompted me to look for a better solution.

After a little research I found a wireless router that uses a USB dongle to connect to the internet rather than a fixed telephone line. The TP-Link MR3420 does everything that a fixed line router does, in fact it can connect to a conventional router to give a failsafe connection. Not all USB dongles are compatible but TP-Link have a list on their website.


I bought one and put it on test using an old unlocked vodafone USB Dongle and it worked a treat with the ‘3’ sim card. I conducted tests over three months to make sure that the mobile solution was reliable, the speed was acceptable and that we didn’t exceed the monthly 15GB allowance. We only suffered one loss of service at home, one evening for around four hours – a transmitter fault I think. The speed varied between 2Mb/s and 6Mb/s which compared favourably with the landline constant speed of 3.5Mb/s. We used between 5GB and 8GB per month. So we took the plunge and had the landline disconnected, all we had to do was switch between the TP-Link at home and the MiFi on board Phoenix III.


Broadband on board

I couldn’t resist experimenting with the TP-Link on the boat but of course the problem is that reception in a steel tube is difficult and with the USB dongle plugged into the router, the option to hang it up in the window as we did with the MiFi became even less practical.

The Dongle

The Vodafone K3765 has a secret, it has a socket for an external antenna connection lurking beneath its white shiny exterior so that opened up a new possibility for me. I removed the cover, marked the position of the socket, clipped the two halves back together without the internal circuit board. I then carefully drilled a 6mm hole in the case before reassembling the dongle ready for use.

There are two versions of the vodafone K3765, the Huwaei version and the ZTE version, This article references the Huwaei version only. It’s easy enough to pick one up on Ebay either as K3765 or E1762. They’re generally unlocked but if you have a locked one you can either take it to your local shopping centre and get it unlocked or do it yourself for less than £5 with dc-unlocker which you can download from the website.

The Antenna

I bought the antenna with a CRC9 adapter, the plug that fits the internal socket on the K3765.


This is a panel mount antenna which requires drilling a 12mm hole in the roof of the boat. Not everyone wants to drill a hole in their roof but magnetic mounts are available. I already had a redundant car radio aerial that I wanted to remove so all that I had to do was enlarge the hole and mount the new antenna. The unit is sealed to the panel with a rubber washer but I wasn’t happy with the seal so I dispensed with the washer and applied a bead of silicon inside and underneath before tightening it all up.

Power Supply

All that remained was to consider power for the TP-Link. It is a domestic unit and is supplied with a 3-pin plug transformer which is all very well when plugged into a shoreline but not really practical if you are out in the middle of nowhere and you have to switch your inverter on just to power the router. Of course if you have no inverter then it’s not going to work at all.

Handily enough, the TP-Link has a 12v dc 1A supply but the last thing that you would want to risk is plugging it into your domestic battery bank, particularly when the engine is running. My final purchase was a car adapter designed for tv/lcd monitors. This piece of kit has an input of between 12v and 30v dc with an output of a constant 12v dc at 5A. The TP-Link has a socket which takes a 2.1/5.5mm plug, the car adapter has a 2.5/5.5mm plug but it still works properly.

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Summary & Cost

With everything in place I actually bought another TP-Link router so that all that needs to be moved between boat and house is the USB dongle. The system works well and I can recommend the quality of the parts that I used. As for the cost of it all, here’s how it all breaks down.

TP-Link MR3420 router                        £27.00

K3765 USB Dongle (Ebay price)        £20.00 ?

Antenna                                                     £35.00

Power Supply                                          £13.00

Total                                                            £95.00

Prices include P&P, the dongle depends on what is on ebay, I already had one so my estimate is based on what is available on ebay at the time of writing.