Thus, the following modifications can be legally applied and used in my circumstances.
It would not be legal to use the modified radio to transmit on frequencies outside of the amateur bands, or of course without holding an amateur license.
Preliminary Preamble
The Intek MT-5050 is a very good radio for the money. As it is, it is a license-free PMR446 transceiver. Like all PMR446 radios, it has a fixed aerial and is limited to 500mW RF power. That's not very good really.
It makes a good 'prepper' radio because it is relatively cheap, simple to use, fairly rugged (although not waterproof), takes easily available AA cells (NiMH, alkaline, lithium energizer), it can talk with 70cm amateur radios and can be modified easily to make it better.
There are two things to do:
A. Increase the power output and channel ranges.
B. Add an aerial socket to allow better aerials to be attached.
Increasing the output power
This, along with increasing the available channels, is very, very easy. Like many modern transceivers, the Intek has 'option' links inside. These are access from inside the battery compartment, under the service label.
The label is just a slip of plastic that can be flicked out with the tip of a knife or tiny screwdriver. Under it is an access hole in which three looped wires can be seen. Cut them all.
Note though that the wires are hard steel, not copper. I ruined the edge of a very expensive miniature wire cutter on them
. Use something with strong jaws, like in the picture below.Once cut, either put a bit of tape or glue on the ends to stop them touching, or do what I did and cut a section out of the wire.
If you are doing the aerial mod as well, it's easier to open the radio as in that part and cut the wires then, without having to work through the little hole.
Once done, put it back together, turn on, and enjoy 4W RF output and more channels to play with.
Adding an aerial socket
Parts required
Intek SMA adapter
Intek KA-505 aerial, long or short
These can be found here: http://www.thunderpole.co.uk/intek-mt50 ... tials.html or on ebay.
Tools required
Soldering iron with a small bit (2mm or smaller preferably)
Solder (fine, like 0.8mm or so)
Philips PH1 screwdriver
Solder sucker or braid (optional)
Soldering flux pen (optional)
Personal ground connection (optional)
Personal ground connection
Most electronics contain chips that are static sensitive. To be safe, you should be grounded while working inside them, and even then don't go touching the PCB more than you need to.
A simple ground can be made by tying a copper wire to a water pipe, which should be earthed usually, and wrapping the other end around your wrist. That's not a safe way really, but it's what I do when I need to. In my workroom I have a fully antistatic workstation though.
If you intend to do a bit of this sort of stuff, buy a cheap antistatic kit (wrist strap, 'plug' that goes into the mains socket and is earthed, and a lead between them).
If you don't do this, you'll probably get away with it and not kill the radio. Most people don't bother, although it does increase the risk of bricking your kit.
The bits that my friend the postie brought me today
The little thing is the SMA socket adapter that needs to be soldered into the radio. AA cell for scale.
Step 1 - unscrew the radio
Time to void the warranty, if you haven't already. There are five small Philips-head screws, size PH1. Unscrew them all and don't lose them. They are marked in the diagram:
[img]hhttp://img121.imageshack.us/img121/3246/intek03.jpg[/img]
Step 2 - remove the case
Be careful here - the front of the radio has a speaker attached with thin wires. Don't pull too hard or they will come off the board. Take care not to stretch them.
The case takes a bit of a wiggle to get off because of the rubber PTT cover and socket cover. Just go easy and wiggle things apart. There are no hidden plastic catches or anything nasty. The Aerial rubber sleeve is loose and can just slip off too, once released from the case halves.
Step 4 - Examine the back of the PCB
Turn the radio so that the back of the PCB is upwards. You should identify the aerial solder joint, marked on the photo. Also, identify a hole at the top edge of the PCB, marked in green on the photo. This is a ground connection.
Step 5 - remove the aerial
Turn the radio back to front-up again. The aerial is best removed from this side by heating the joint until the solder melts, then pushing on the end of the wire with the tip of the soldering iron to push it through. Mine just fell out but you might need to just pull a little on the aerial.
Don't leave the iron in contact for too long, no more than say five seconds, because it can melt the tracks off the PCB. If you do leave it on too long, leave it all to cool down fully before doing anything else. Hopefully the glue will re-set properly. Five seconds (it's longer than it sounds) should be plenty if your iron is at the right temperature.
If you have a solder sucker or braid, you could use this to remove excess solder first - I did with a solder sucker. If you don't, you might end up with solder filling the hole in, or you might get lucky and not.
Step 6 - fit the adapter
Turn the radio over again. The adapter has a metal lug and a wire. The wire goes to the hole that the aerial was in and the lug goes into the ground hole indicated earlier.
Before fitting the adapter, if you have a flux pen use it to coat the end of the lug, the wire and both holes. This will make soldering it much quicker and easier. Flux cleans the surface and prepares it for taking solder.
The lug should stand vertically from the PCB so that the adapter is about level with the volume knob as shown in the photos. The wire (not the lug) needs a little bending to get it in place too.
Step 7 - solder the adapter in place
Turn the radio over, yes, again! This bit can be tricky, trying to keep the adapter in the right place while turning it over and while soldering it. I propped and wedged it but a second pair of hands to hold it might be better. Take your time to get it positioned and secure before trying to solder it, otherwise it will just move as soon as the iron touches it.
Solder the lug first so that it holds the adapter in place. As before, try not to keep the iron on the joint for too long.
If you're not used to soldering, read up on the web but the basic principle is to apply solder and iron together to the corner of the joint, heating everything at once. Allow the solder to flow into a liquid, conical pool around the joint, then remove them together. Let the area cool before doing the next joint.
The joints should look shiny and smooth when set. If they look grey and matt, that's a dry joint caused by things like too cool an iron, cooling too quickly (don't blow on it), or poor surfaces. If that happens, you'll need a solder sucker or wick to remove the solder and try again. Dry joints eventually fail even if they work at first.
Step 8 - reassemble the radio
I fitted the PCB into the front, with the speaker, first.
The aerial adapter has small location grooves that fit into matching grooves in the case halves. Push it home carefully, it might take just a touch of turning to align. If soldered vertically though it should be lined up almost exactly.
I found it a bit tricky to get the PCB seated properly, not sure what was catching but it took a fair bit of careful wiggling to get it into place. Patience is a virtue, so I'm told. Make sure the rubber keypad is properly in place and that the speaker wires aren't trapped or covering the screw holes.
Fit the rubber PTT cover and socket covers - they slide tightly into slots. Make sure they look right from the side before fitting the back.
The back might feel just a little as if it wants to spring off a mm or so - that's because there's a springy heat spreader inside that needs to be pressed against the chip. A gently squeeze should hold it closed though - check the seam all the way around and try again if it looks amiss.
Finally, screw back together. If you're not used to putting self-tapping screws back into their holes, this is the trick to avoid stripping the holes: put the screw in, and use the screwdriver to turn it backwards while pushing very gently. You should be able to feel when it drops into the start of the plastic's thread. When it does, that's the point to start to screw it gently in.
Finished - test time!
Now you can fit your new aerial. Screw it gently home (just finger tight, that's all it needs). Put the batteries in if you haven't already and switch on.
First, ideally, try just receiving a signal from a good distance. Make sure it seems right. If so, try transmitting on low power first. Check that the received signal at the other ends seems good. If so, try high power and check again. With a longer aerial, you should notice a fair difference in range/signal strength.
) Maybe if we ever get an RV sorted you could prehaps runa workshop on alternative comms?
