[Elecraft] VLF/LF Converters

[Ron D'Eau Claire]

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