Reprinted from the November 1998 CQ Magazine with express permission.
The SGC SG-231 Smartuner
With ever increasing population and the increased restrictions within subdivisions and apartment complexes, it is becoming more difficult to obtain a good antenna installation. If you add to this scenario the fact that you might want to work several bands in the HF to lower VHF spectrum, then the problem is multiplied several times.
The SGC corporation may have just the answer to your dilemma. The SG-231 Smartuner is a microprocessor-controlled automatic antenna coupler that can provide millions of settings for requirements from 1 MHz to 60 MHz. Once the proper matching conditions are determined, the settings are stored in non-volatile memory for almost instant recall.
Meet the Smartuner
The SGC-231 is a fully automatic antenna coupler for 3 to 100 watts with a range of 1 to 60 MHz. It uses a microprocessor-controlled pi or L network to match almost any load to your rig with a resulting SWR of 1.4:1 or better. Tuning results are stored in a non-volatile memory to produce almost instantaneous recall. It requires a 12 volt DC power source at about 900 ma.
The unit is an antenna coupler that is mounted at the antenna as opposed to the transceiver location. There are some exceptions to this rule, but more about that later. As long as a suitable antenna length is maintained (7 feet for 3 5—60 MHz, or 23 feet for 1—60 MHz) in conjunction with an efficient ground or counterpoise, the Smartuner will provide very efficient transfer of HF energy to the antenna. Remember, when energy is generated by a transmitter, it will be radiated by the antenna or dissipated as heat. By installing the Smartuner at the antenna, the coaxial feed line will see a minimum mismatched condition, and losses in the feeder will be diminished greatly. This ensures every possible watt of power is radiated to the world.
In the World of Restrictive Antenna Covenants
In the world of amateur radio, we find ourselves facing progressively more antenna restrictions. Well, we could succumb to the pressures and take up bridge, or we could look for alternative ways to satisfy our longings for communications. With the increase in propagation conditions, I suggest the latter. Within the instruction manual there are several stealth-type antennas suggested—for example, a heavy-gauge wire taped to the inside of a PVC pipe, with the pipe is made into a flag pole. (Who could refuse a home owner the right to install a flag pole on his/her property"? That would be totally unpatriotic!) The only thing remaining to turn this into an antenna is to bury several radials and mount the antenna coupler at the base of the flag pole. When you connect the coax and the control cable, you are in business.
Another opportunity for a stealth antenna is to run a heavy gauge wire adjacent to a masonry chimney. Again, mount the Smartuner at the base of the chimney, bury the radials and control cable, and tune in the world.
If your house has a non-metallic roof, don’t forget the possibly of suspending a wire underneath the eaves. When this wire is extended to the ground, you have an inverted L "Small TV type stand-off insulators can supply the physical support needed for the wire. Mount the Smartuner, add the radials, bury the feed line and control cable, and call CQ In each case, if the Smartuner is adjacent to a metallic water line, be sure to connect the radials and Smartuner to this facility. Remember, the better the ground system, the more efficient your antenna system. Do not connect the ground system to a gas line!
What About Mobile Installations?
There are several types of mobile installations that may be of interest to you. The most common, of course, is the use of one of the modern transceivers in the family car. There are two things that warrant careful consideration the length of the antenna and the vehicle ground. For operation from 3 5 MHz through 60 MHz, the minimum length of the antenna must be 7 feet. To extend the coverage down to 1 MHz, the antenna length must be extended to 23 feet In both cases, an efficient ground must be implemented.
Also under the category of mobile installations, we must consider the world of sailboats and recreational vehicles. There are several examples in the instruction manual covering these applications. Insulated back stays become a natural choice for an antenna on a sailboat. Two examples are given for implementation for the boating public. The first is for a non-grounded keel, the backstay and metallic mast form the antenna system. The second example shows an insulated backstay for the antenna, and a metallic keel as the ground system. If you have spent a lot of time on the air, chances are you have worked someone on a sailboat. I am always surprised at the signal strength of these stations. It is very difficult to find a better ground reference than salt water!
I could continue with examples of different installations, but on to the actual test results.
Installation and Test Results
I made my initial tests with one of my QRP transceivers and my 40 meter Double Extended Zepp (total length of 178 feet fed with a random length of balanced line). Implementation was very simple It only required connecting a 12 volt source to the SGC-231, connecting the output of the antenna into the tuner, and connecting the antenna and ground to the output of the Smartuner. When the unit was supplied a source of RF energy, it tuned the system automatically The Smartuner tuned the system almost immediately (less than 3 seconds initially) to an acceptable SWR. I checked the Smartuner on all amateur bands from 160 through 6 meters. The Smartuner performed flawlessly throughout the spectrum On 17 meters, I was pleased to make many contacts with several stations in the northwest. That was not bad for 5 watts on single sideband!
For my next test, I moved from my ham shack to my patio to simulate emergency conditions. Again, I operated QRP, but this time the antenna was a 23 foot length of wire connected to the output of the Smartuner. I ran a 100 foot length of wire along the ground and connected it to a screwdriver pushed into the ground. The Smartuner again worked extremely well, even under these simulated emergency conditions I did not work as many stations under these conditions, but I did not expect the same results. The test did prove that the Smartuner will perform well, even under marginal conditions.
The Instruction Manual
Sometimes you buy a piece of equipment, and after reviewing the instruction manual you are left with many unanswered questions. I am happy to report that this is not the case here. The manual is very clearly written There are many well detailed sketches showing possible antenna installations. This is one of the better manuals that I have seen recently.
I was very pleased with the test results that I obtained. I feel that this technology can provide the amateur radio operator with covenant restrictions a way out of his or her dilemma. With the hints provided in the manual and the potential users imagination, there is a solution for every antenna problem.
*97 West Point Road, Jacksonville, AL 36265
SGC Inc., Tel:
425-746-6310 Fax: 425-746-6384
Email: email@example.comSGC reserves the right to change specifications, release dates and price without notice.