I recently ordered a Tecsun PL-600 to go to the next step of shortwave listening. It has lots of cool features that my current receiver – a SilverCrest Digital World Receiver I got in Lidl for about €15 some years ago – doesn’t have. So, I took this as an opportunity to improve the SilverCrest without fear of causing permanent damage to it. For years I’ve been using a simple random wire clipped to the whip antenna on the receiver to listen to stations from around the world. The method has served me well so far, but I wanted to be able to connect a proper antenna fed with a coaxial cable. I decided to add an RF socket to the SilverCrest.
This modification can be applied to any similar portable radio: all we’re doing is connecting the centre conductor of the RF socket to the whip antenna, and the outer shield connector to the battery ground. The whole process probably won’t take more than 30 minutes.
You will need:
- RF socket
- A short length of coaxial cable (I used speaker wire, but coax would be better)
- Soldering equipment
- A drill
- Screwdrivers, wire clippers, wire strippers, etc.
- A beer
After you’ve opened your beer and enjoyed your first mouthful, remove the batteries from your radio, remove the screws, and carefully open it up. Inspect the radio interior and look for somewhere that has enough room to place the RF socket. Somewhere close to both the battery ground and the whip antenna would be ideal so that the length of the wire/coax cable used is kept short, but in my case I chose the opposite end of the radio set where there was more room for the socket and wire.
You will also need to examine the layout of the whip antenna and its connection to the tuner. In my case, it was much easier to connect a wire to the antenna base, but on your radio you might find it easier to solder the wire from the RF socket to somewhere else along the antenna connection to the tuner. Also consider internal obstructions like screw sockets, or other obstructions that may be present when you put the radio back together.
When you’ve decided where to put the socket, get out your drill and carefully and slowly drill a hole through the plastic (too fast and you risk breaking or melting the plastic). I used a Bosch 10mm drill bit with a point, but if your bit doesn’t have a point, you might prefer to make a small pilot hole to stop your large bit slipping on the plastic. Make sure the edges of the hole are nice and smooth for a good flush fit of the RF socket.
When you’ve fitted the socket, it’s time to start connecting some wire. Ideally, you would use coaxial cable here so that you don’t pick up any interference from the electronics in the radio itself (the outer braid in coax is a shield for the conductor wire inside), but again, this depends on how much space you have and where the socket is positioned. If you use coax, also keep the impedance in mind in case you want to match a feedline from your external antenna. For the SilverCrest, I used twin lead as some of the space in the radio was a bit tight, and it was much easier to fit and bend than coax.
Lay out whatever wire you decide to use inside the radio to get an idea of how long you should cut it and how much insulation you should strip. When you’re happy, cut the wire, strip it, and solder it to the socket. If you use coax cable, solder the central conductor of the cable to the centre pin of the socket, and the shield braid to the protruding connector.
Next, the wire coming from the outer connector of the socket should be soldered to the negative terminal of the battery enclosure (or the negative terminal of the DC power socket), usually denoted with a black wire. The “live” conducting wire needs to go to the antenna. In my radio I simply loosened the screw for the whip antenna, placed the wire underneath it, and tightened the screw again to clamp it tight. You might decide to connect or solder it to the antenna or the wire between the antenna and the radio tuner in some other manner.
When you are happy that everything is in place and correctly connected, carefully reassemble your radio, making sure that screws are going into their correct places, and than no switches or panels have fallen out. Put the batteries back in and turn on your radio to make sure it’s still working.
Hopefully, everything should be in working order, and you’ve successfully modified your portable radio in the time it takes to have a beer!