On 16 July 2015 at 08:05, Ole Stender Nielsen <[email protected]> wrote:
> I use a home-made untuned loop antenna with 4 windings of 2.5 mm2 > insulated wire on a 80 x 80 cm wooden frame, and with a grounded base > pre-amplifier mounted on the antenna frame. A schematic is enclosed for you > to copy. > Thank you. I will build one of those. I have most of the parts here, but not the transistors. > The pre-amplifier is powered through the cable, and loads the FS700 input > as required. > I live about 290 km from the island of Sylt, and get nice noise margin > figures from the FS700, normally about 40 dB, often up to 46 dB. > It's odd that http://www.loran-history.info/sylt/sylt.htm shows Sylt as closing in 2006. Did Sylt ever close and then re-open, and that web site just out of date? I'm a little further than you (321 km vs your 290 km) from my nearest transmitter. I'm located in Althorne, Chelmsford, Essex, UK (51.6517913 N, 0.7752657 E) and I *believe* my nearest Loran-C transmitters are 1) Lessay, France, power = 250 kW, distance = 321 km, bearing = 211 degrees. 2) Anthorn, England, power =- 250 kW, distance = 419 km, bearing 331 degrees. 3) Sylt, Germany, power = 250 kW, distance = 611 km, bearing = 52 degrees. 4) Soustons, France, power = 250 kW, distance = 896 km, bearing 191 degrees 5) Edja, Fraoe islands, power = 400 kW, distance = 1274 km, bearing = 341 degrees. > For larger distances to the transmitter site, you may need to insert > additional amplification between the grounded base pre-amplifier and the > FS700, and that requires that you provide power to the pre-amplifier > through a bias Tee, and that you load the FS700 input to keep it happy. A > while after I installed the antenna in the attic, I added additional > amplification, not due to a low signal level, but because I wanted to use > the loop antenna for other longwave services too, and that required that I > had to split out the signal. > > Best regards > Ole > Thank you Ole. That at least gives me something to start from. I guess the op-amp design Poul-Henning Kamp used offers more flexibility for gain adjustment. I might look at that too. If the amplifier is in a box with a couple of banana jacks and a BNC socket, it is fairly easy to change one amp for another. I assume from what you say that the FS700 will report the Dave _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
