The SGC antenna couplers (AKA external tuner) are versatile devices. I have been using a SGC 237 at home. I use a 100 foot run of coax via the attic from the shack in a front bedroom to where the coax exits the back of the house. Just outside the wall I have the SGC 237 coupler. The output connects to balanced 300 ohm line that feeds a 135 foot doublet with the center in a tall pine tree. After tuning the 100 foot line operates with less than 2 to 1 SWR. Therefore mismatched loss is minimal. To tune, I just apply RF power long enough for the tuner to do its thing. This all works smoothly except 10 meters CW where it tends to retune unnecessarily. I am just going to accept that for now. It is possible to have a control box to lock the tune but I will keep it simple.
I decided to keep the SGC 237 in place at the house, so I never tried it out for portable use. However, I now have an Icom 7100 which may be deployed for Field day or similar events. The Icom 7100 does not have a tuner. Therefore, I have invested in a second SGC 237. Being able to locate the tuner/antenna remote from the operating position can come in handy. Perhaps I want to be under a pavillion but have the antenna at some distance from the pavillion.
Lately, I have been trying the SGC 237 out in the field. I have used it with the KX3 as a substitute for the Icom 7100. I setup two configurations. First is a 30 foot vertical wire and two 45 foot wires as a counterpoise. The second is a 100 foot loop wire as a delta loop. These configurations are pretty easy to setup and tune on 40 through 10. I had to work pretty hard making QSOs on the higher bands on the first try. However, it may have been conditions and congestion on the bands. My last outing with the loop at lunch time was better. I had contacts on 15, 17 and 40 meters with the loop with ease.
Of course, from a RaDAR perspective this is an extra box and you have to wonder if it is worth the setup time. The KX3 has its internal tuner. The jury is out on that. But for Field Day and JOTA plan to put the SGC 237 to use with the Icom 7100. Another application is my parents house where I have the wires for a off center fed dipole in the trees. The balun was destroyed in the ice storm.. I may replace the balun with a center insulator and run 300 ohm line to the SGC 237. The SGC will be setup just when I am on a visit.
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| Vertical configuration |
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| Vertical configuration |
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| 100 foot delta loop |
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| 100 foot delta loop |
