Other Shack Equipment
Other bits and bobs in the shack that may be of some interest.
MFJ-971 Manual ‘QRP’ antenna tuner
When they named this a QRP tuner, I personally thingk they were wide of the mark and missing the point of QRP as it does from 0 to 200 Watts. To use this box for QRP you will need to change two jumpers which are easy to locate, and look much like the jumpers you would expect to fund on a PC motherboard. Moving these to the alternate position knocks the range down from 0-200 to 0-30 watts, further there is a push button on the back that drops the range even more to 0-6 watts. In my opinion there are a few issues with this tuner, however I really like it. For the sub £100 ticket it’s a very useful tuner indeed. It has a built in vSWR meter with cross needles that read forward and reverse power, and although it is spec’d to tune from 0 to 30MHz, I’ve found from personal experience that (at QRP power <5w) it’s fine for tuning up on 6 meters nicely too. On the front there are two trimmers, one labeled ‘transmitter’, and one labeled ‘antenna’, there is also a rotarry switch for Incucatance. On the back of the unit, there are two SO239’s, in and out, and also 3 terminal posts to allow use of a long wire, and a balanced line. On the down side however the knobs on the front have a hole in the side where the screw holds them on. These screws are in contact with the air-cored variable capacitors, and are just shallow enough to allow you fingers to come in to contact with them. Unfortunatly this results in a burning sensation in your fingertips should you be tuning a random wire, or dipole, even as low as 2.5 watts – heavens knows what that would feel like at the maximum spec of 200 watts!!!! , my solution is to put some blu-tack into the holes as an insulator – this will save your fingers from the RF!!! these knobs are very cheap indeed. Going around to the back of the unit, I think MFJ must have used the cheapest 4mm terminal posts they could find. Internally the circuit board edges are a little rough, and are rather close to the metal enclosure. All that aside, for the price this is certainly one cool ATU, and I’d reccomed it to anyone, although – Mind Your Fingers – RF is HOT!
Mountain Radio Rig Blaster Plus
This bit of kit is a nice enabler for access to the data modes. When you get it out of the box, you will find that the lid has already been removed, this is to remind you that you have to set the internal jumpers to suit your particular radio configuration, and irritatingly the main manual has the incorrect instructions for some yaesu tranceivers, however there was an extra enclosed note giving the correct jumper configuration and mentioning the error – which I thought was nice of the guys at Mountain Radio, it wouldn’t be good to blow up your nice shiny new rig due to a documentation problem. After purchasing it I was surprised that I didn’t have the forethought to make my own, however it is a polished product. Essentially it allows you to connect your computer soundcard to your transceiver and uses an RS232 serial port to control the Push To Talk function. The product shipped with CDROM containing several bits of windows software that are already available on the internet that allow you to decode various digital modes. The nice thing is that they were all in one place and make a nice library, although I’m sure they’re all getting a bit dated now. I use this bit of kit mainly to get me working SSTV and PSK31, although it contains other software such as EME (Moon bounce) and meteor scatter by means of PSK441. It’s a nice piece, that works with a laptop + tranceiver configuration. If you’re going to make your own, a good source of impedance matching transformers and relays are old computer modems. Mountain Radio make a couple of other versions of this device, the cheapest being the NO-MIC version. This doens’t have a socket for plugging your MIC in and so if you want to work telephony and Digi on the same radio, theres a lot of plugging and unplugging to do, but the price diffference on reflection would make it worthwhile grafting your own mic switching system on to the NO-MIC version. There is also a ‘pro’ version – which I think is an odd name for a bit of kit primarily used by amateurs!! Still here it is