"RB" wrote in
:

Got a question on LORAN sets. I don't want to get into the
desireability of GPS as the nav mode of choice today. I'm fiddling
around with LORAN and trying to get going with it.

1. What is/are LORAN operating frequencies?
100 Khz, all stations are on the same frequency, exactly. They use a
cesium beam frequency standard to make sure it's perfect.


2. Marine LORANS are found with external couplers (pre-amps) which go
at the base of the fiberglass/whip antenna. Can marine LORANs which
are made for use with external couplers give reasonably good
performance without the coupler? Or, is lack of the coupler a
"killer"?

Killer. The very-low frequency LORAN antenna is electrically 2340' long
(1/4 wavelength on 100 Khz). To achieve this in an 8' long whip it is
VERY heavily loaded with a large inductance and that coupler. No, you
can only get it working with the cou0ler or a 2,340' long whip, your
choice.


2. Are there marine LORAN receivers which don't require external
couplers (i.e., that hook direct to the antenna)?

The couplers on the marine antennas are built into the whip. They're
still there.


3. If you have a marine LORAN which does in fact need an external
coupler to get enough signal through and you don't have the companion
coupler unit, are any commonly available pre-amp boards for the LORAN
frequencies available? If so, where find?


It's not a preamp problem. There's tons of signal from teh MEGAWATT
LORAN-C pulse transmitters and their massive capacitor hat loaded 850'
tall antenna towers. The problem is that 2340' 1/4 wave whip it takes to
hook 'em up.

You need the antenna system it came with.....

"Larry" wrote in message . Killer. The very-low frequency
LORAN antenna is electrically 2340' long
(1/4 wavelength on 100 Khz). To achieve this in an 8' long whip it is
VERY heavily loaded with a large inductance and that coupler. No, you
can only get it working with the cou0ler or a 2,340' long whip, your
choice.


2. Are there marine LORAN receivers which don't require external
couplers (i.e., that hook direct to the antenna)?

The couplers on the marine antennas are built into the whip. They're
still there.


3. If you have a marine LORAN which does in fact need an external
coupler to get enough signal through and you don't have the companion
coupler unit, are any commonly available pre-amp boards for the LORAN
frequencies available? If so, where find?


It's not a preamp problem. There's tons of signal from teh MEGAWATT
LORAN-C pulse transmitters and their massive capacitor hat loaded 850'
tall antenna towers. The problem is that 2340' 1/4 wave whip it takes to
hook 'em up.

You need the antenna system it came with.....

While there is certainly no question that the matching coupler and 8' whip
are pretty much standard, just for fun we experimented with some of the old
TI lorans, and found that the SSB antennas on many power and sail boats
worked fairly well, with one major "gotcha". Loran C, at 100 khz is very
easily messed up by electrical noises from almost anything on a boat. Having
the 8' whip antenna up and away (several feet at least) from the noise
makers and the boat's wiring, made major differences in noise pick-up. Water
damaged TI loran couplers were pretty common, and you could pull the guts
out and throw them away, and jumper the whip connector to the signal feed
wire inside the coupler. Performance not perfect by a long shot, but if you
shut down the main engine and everything else, you could get a fix. (the
hard way)
Old Chief Lynn

OK. Thanks, Larry. That means all those nice LORAN receivers for sale on
Eprey without couplers basically aren't useable. Which is probably why the
go so cheap......