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Ok Ok... It was back in the 1950s but interesting to see.
http://www.archive.org/details/LargestR1950

I went thru this facility in the mid 1960's with my electronics class from
Western Washington University and it was something I will never forget.
(Kind of dates me... :D )

You can still see the lights on it's towers driving on I-5 if you look east in the hills
just north of the Arlington exit.

It is actually located 30 miles east of I5 at Oso, WA.

There are 6 towers located on the hills on each side of the valley.
The span is over a mile across. The antenna actually forms a 6 element beam
pointing west across the Pacific ocean.

The call sign is NLK and it operates on a VLF frequency just above 20KHz.
At that frequency the RF signal stays very close to the surface of the earth
thus the very high power it transmits. It is able with that power to transmit
a signal to a submarine 100 feet under water anywhere on earth.

At this very low frequency the wave length of the antennas is very long.
The station has massive components and looks more like a hydro electric dam
inside than a radio station.

Each stage of the transmitters circuits has it's own room. The technician
there said it was easy to troubleshoot. "You just look for the room with
nothing lighting up in it"

There are now more powerful transmitters but this was the 1st real power
house in the world.

The chocolate cake they served in the mess hall is still the best I have ever eaten to this date :D

_________________
" SILENCE IS CONSENT "

Made to Government Specs:
1) Measured with a micrometer.
2) Marked with a chalk.
3) Cut with an axe.

Jim N7UAP - Bellingham, WA / InterceptRadio.com

Here is a link showing Jim Creek.

You can see the building in the last ariel photo and also the towers on each side of the valley.

http://www.trust-us.ch/cryptome/02-Eyeb ... yeball.htm

_________________
" SILENCE IS CONSENT "

Made to Government Specs:
1) Measured with a micrometer.
2) Marked with a chalk.
3) Cut with an axe.

Jim N7UAP - Bellingham, WA / InterceptRadio.com

Is this station still on the air?

I thought I had heard it was being de-commissioned a few years ago, but I could be wrong.

According to this link Jim Creek is still on the air...

http://www.spacenv.com/~rice/vlf/2008/index.html#NLKday

_________________
" SILENCE IS CONSENT "

Made to Government Specs:
1) Measured with a micrometer.
2) Marked with a chalk.
3) Cut with an axe.

Jim N7UAP - Bellingham, WA / InterceptRadio.com

It's a museum now. The Navy uses airplanes to relay messages to subs. It sounds like this:

http://www.microvoltradio.com/wav_files ... jected.mp3

I thought they used multiple modes VLF/HF/UHF for those calls in the past. I imagine that there are antennas on the bottom of the oceans by now.

museum = old crap in a lock down building
museum = pay 5 bucks and stick your nose on the glass and say ..ohhhhh

_________________
If I had an antenna, I would; but I can only transmit on 160 meters.
_____
DE K7MHI

A powerpoint slide show of Jim Creek is on this link...

http://navymars.org/pacific/reg10/jimc.htm

_________________
" SILENCE IS CONSENT "

Made to Government Specs:
1) Measured with a micrometer.
2) Marked with a chalk.
3) Cut with an axe.

Jim N7UAP - Bellingham, WA / InterceptRadio.com

Years ago, I went camping at Jim Creek with my boy scout troop. I think it's still used for that, mostly by military families, or by special permission, like we had to get.

Nice pics. I haven't been inside the transmitter building since the early 1980's. Looks like a few things have been updated since then !

Last I heard, Jim Creek was being shut down but two other VLF sites NAA (Maine) and NPM (Hawaii) would remain online. Apparently the ELF site at Clam Lake (Wisconsin) is gone too. Not sure about the other VLF/ELF transmitters.

I doubt VLF will ever be entirely scrapped as its the only way to signal a fully submerged sub. Once signaled on VLF, a sub can go near-surface and launch a FleetSatCom buoy for 2-way comms if necessary.