On 15 Aug 2014 at 20:57, paul swed wrote:

2 Megawatts to that antenna should show VOLTS at your place.

We used that station for many years for VLF propagation research in
Missoula, Montana. It banged in 24/7/365. Still does, except when its down
for maintenance.

So did Jim Creek (of course) and NWC in Australia, and a station whose call
I have forgotten in the Canal Zone.

Back in 1973.

Ken W7EKB

Ken
At least last night NAA was running just fine using a fluke 207 and 4 ft of
wire.
The antenna is behind a metal rack that shields it in NAAs direction. I did
that test out of curiosity.

Granted its 2 MW but then again the antenna is at best 50% efficient.
Who knows maybe they have sections of the antenna down for maintenance.
Regards
Paul

On Fri, Aug 15, 2014 at 11:22 PM, Kenneth G. Gordon <
kgordon2006@frontier.com> wrote:

Hi

I would be very surprised if the NAA antenna was 50% efficient (transmitter RF to radiated power)…..

Given that it’s already up and running with good signal levels, that’s not a big deal.

Bob

On Aug 16, 2014, at 10:24 AM, paul swed paulswedb@gmail.com wrote:

Bob
The fact is its on the web. :-)
I was surprised that the documents said that also given most LF Ham systems
are very inefficient given what we have to work with in $ and space. But
then again its no an amateur installation. With 16 X 825 ft towers and
miles of wire over salt flats and water. Matching systems that are like a
Frankenstein movie.
Regards
Paul
WB8TSL

On Sat, Aug 16, 2014 at 11:33 AM, Bob Camp kb8tq@n1k.org wrote:

On 16 Aug 2014 at 11:33, Bob Camp wrote:

According to this:

http://www.scribd.com/doc/145116437/THE-BIGGEST-LITTLE-ANTENNA-IN
-THE-WORLD-US-Navy-s-VLF-antenna-at-Cutler-Maine

The company which designed and built the dual trideco antenna system at
Cutler had to guarantee >50% radiation efficiency, and they achieved an
antenna radiation efficiency of 74.9% when using the 6 panel trideco.

When I read this, I was truly amazed.

Although, this site:

http://www.navy-radio.com/commsta/cutler.htm

does say that with 2 MW input, the ERP is 1 MW, which would indicate at
least 50% radiation efficiency.

I am still amazed.

Very true indeed.

Ken W7EKB

On 16 Aug 2014 at 10:24, paul swed wrote:

Ha! At VLF you could probably bury your antenna in a grounded, steel pipe 4
feet into the ground and still hear NAA.

I LOVE curious... :-)

See previous post.

The reason NAA has a double trideco is so they can continue to transmit
with one section down for maintenance.

It turns out that Cutler has a much-bigger-than-usual problem with lightning...

Ken W7EKB

Kenneth on the opamps that is correct.
But I put little U's to indicate phase. They actually represent the top
half of the input cycle.
In the top path it inverts once
The bottom path twice.
So that makes the top 180 out and the bottom in phase with the original.
However the 2 X RC sets the bottom path at I believe 180 degrees from the
input.
The final RC in the top and bottom path account for opamp filter delay and
note they are equal.
So thats has me scratching my head as to how this removes the MSK and
leaves a carrier that can lock.

One of the classic approaches to recover carrier or get rid of BPSK
modulation is to simply double the incoming carrier. Works great if you
don't loose the signal.
But I do not see this circuit doing that.

Regards
Paul

On Sat, Aug 16, 2014 at 12:20 PM, Kenneth G. Gordon <
kgordon2006@frontier.com> wrote:

On 16 Aug 2014 at 13:35, paul swed wrote:

Yes, I saw those, but unless I am mistaken, you didn't add a "U" after the
second opamp, which would have returned the phase to the input's.

I see twice: once through the first op amp and again through the second one.
The second one then outputs to the IF.

Anyway, to me, it is a very interesting and simple circuit.

I LIKE "simple". I am a great believer in the KISS principle.

Ken W7EKB