Larry W4CSC wrote:
"RB" wrote in
:

Does the length of a LORAN metal whip matter much?

Yes, it matters a lot. Loran operates at 100 Khz, Very Low
Frequency. The antennas are heavily coil loaded to tune them at this
low a frequency and very narrow banded. The whip length is part of
this tuning and if you change it to a different length the antenna is
way out of tune and not near as sensitive. It may still function out
of tune, but signals will be down.

That's about the same frequency as my sextant works on.

"Dennis Pogson" wrote in
:

That's about the same frequency as my sextant works on.


You should see the TRANSMITTER and it's huge antenna at this frequency.
I've visited many LORAN "C" installations across the South and calibrated
their test equipment in a mobile cal lab. Try reading a scope in between
megawatt power pulses when you're lab is located BETWEEN the huge capacitor
hat 800' above you and the massive ground system buried right under you.
Everything in miles has LORAN pulses on it....

If you ever get the chance to go by any LORAN station, do so. Knock on the
door and tell the Coasties thanks for providing you with nav at sea.
They'll be glad to show you their beast.

The antenna, by the way is 800' high with a 36 spoke capacitor hat about
500' diameter made of bridge cables at the top to tune it at such a low
frequency. The transmitters are all solid state. The output power
actually comes from multiple drawers of Silicon Controlled Rectifiers,
thousands of amps, pulsing from cesium-beam frequency standards as the
pulse timing of LORAN is very critical to its positional accuracy.

It's all obsolete, now that GPS works so good. Politics keeps it on the
air....

LORAN "A", the one from WW2, was on 1.9-2.0 Mhz above the standard
broadcast band. Its antennas were much smaller because of the higher
frequency. It was useless at night or in a storm because of the "skip",
same physics that lets you listen to an AM radio station 800 miles away all
night. Charleston had one on the very northern tip of Folly Beach run by a
few sailors who lived across the street from the transmitter. Fine duty
back in the analog days...(c;