Or better pre-selection, such as a high-Q tuned antenna. I don't mean a typical active antenna either. Most of them are a broadband amplifier hooked to a whip. Signals way off frequency are amplified right along with the desired ones and no amount of "preselection" after the antenna is going to help once the amplifier at the whip has generated broadband cross mod.
When I lived near Portland I had that problem on any MF receiver I tried, so I built a small ATU for that range and hooked on my HF antenna as a "random wire". With the tuner in the circuit the MF range went from noise caused by BCB and every other sort of monster signal overloading the RX to Q5 copy of a large range of non-directional beacons (NDBs) and stations like KPH. Those NDBs only run 50 watts or so into a short antenna, yet I copied many of them over a range nearly 1,000 miles when cdx were good. All that aside, the fate of the 600 meter band seems sealed because the US Coast Guard (USCG) has reserved virtually the whole 400-500 kHz spectrum for low-frequency GPS beacons. Those beacons will transmit correction signals that improve the accuracy of GPS sufficient to control vehicles on the ground and to land aircraft. (It's no surprise that almost all of those beacons are slated for installation at airports.) I'm a little surprised that the FCC has issued some 600 meter licenses to coastal stations since, but those may be subject to cancellation at any time the USCG wants, just as the Amateur experimental license is provisional. So, one of these days, the 400-500 kHz band will be wall-to-wall data beacons bleating out their information to GPS receivers nearby, and in the slot just above 500 kHz and below the AM broadcast band we still have NAVTEXT broadcasting text weather reports to ships. I don't know the fate of the LORAN system there. It's been heralded as a "backup" to satellites, and there's some good sense in doing that. It all depends upon Coast Guard priorities with their greatly-expanded Homeland Security mission since 9/11. Ron AC7AC -----Original Message----- I'm on the west coast [near Sacramento] and about 120 miles from the XRAY-9940 LORAN-C station at Middletown CA, and about 190 miles from the Master-9940 at Fallon NV. Both run 400KW peak [I think]. That's about all I can hear anywhere from below 100 KHz to 400 KHz or so with my Palomar VLF converter, the signals are huge. Maybe I need a different VLF box. 73, Fred K6DGW _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
