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    Re: LORAN-C to be shut down.
    From: Gary LaPook
    Date: 2009 Dec 9, 02:23 -0800

    You might like this site which calculates loop antenna data.
    
    http://www.mindspring.com/~loop_antenna/amloop_calc4.htm
    
    gl
    
    On Dec 6, 8:01�am, Apache Runner  wrote:
    > Another enhancement, which is perhaps cheaper is the so-called sportsman's
    > antenna. � It consists of a large wire loop and tunable capacitor. � You put
    > the loopstick radio inside this - properly oriented. � �The idea of the
    > sportsman's antenna came from the days when radio and TV stations close to
    > pro-sports games were blacked out, and people would build these antennas to
    > enhance the signal, so they could listen in on distant stations.
    >
    > It turns out that these are highly directional with very deep and well
    > defined nulls. � There's an article about this at the following PDF
    >
    > http://www.dxing.com/tnotes/tnote09.pdf
    >
    > Here you could take a radio like Gary's Grundig and place it inside the loop
    > antenna and use it as an RDF. �I'm curious about the precision one can reach
    > with a device like this.
    >
    > On Sat, Dec 5, 2009 at 8:58 PM, Lu Abel  wrote:
    > > �Why build your own?? � Many cheap AM receivers use a loop antenna which is
    > > fairly directional.
    >
    > > I also wonder what benefit one gets (other than "yes, it can be done"
    > > satisfaction) of creating a RDF with 3 degree accuracy. � Each degree of
    > > bearing inaccuracy gives 100' of inaccuracy per nautical mile of distance
    > > from the station. � Shoot a station from 10 nm offshore with your proposed
    > > RDF and you have a 1 nm inaccuracy in your LOP!
    >
    > > Apache Runner wrote:
    >
    > > Although this is a completely out-of-the-box idea, I've been working on an
    > > AM radio receiver/direction finder for fun. � �The FCC publishes the
    > > lat/long for all stations in the US.
    >
    > > I haven't seen a variable capacitor in ages, but managed to find some
    > > beauties online, and am making my own antenna. � �Right now, I think I can
    > > get an accuracy of maybe 3 degrees, but that's just a guess.
    >
    > > I'll post something when I have it up and running.
    >
    > > On Sat, Dec 5, 2009 at 3:03 AM, glap...---.net wrote:
    >
    > >> I know we have some commercial air pilots on the list and was
    > >> wondering if
    > >> they thought an aircraft RDF unit could be easily mounted on a boat.
    > >> The
    > >> aircraft industry seems to be the only ones making small units these
    > >> days.
    > >> I might go ocean cruising with a friend who is presently re-fitting
    > >> his
    > >> boat, and I am a big fan of redundancy, and thought this might be a
    > >> workable
    > >> solution.
    >
    > >> ---------------------------------------------------------------------------
    >
    > >> An ADF will work on a boat but they aren't cheap, the readout is only
    > >> marked every 5 degrees and the antenna has to be mounted somewhere. If
    > >> you want RDF capability just by an inexpensive digitally tuned
    > >> portable radio that covers the LF band such as the Grundig G5 which
    > >> also covers HF and has SSB capability so you can get your time
    > >> signals �too. These all have ferrite rod internal antennas which are
    > >> highly directional. Get one and tune a distant station. Then orient
    > >> the radio in different attitudes and rotate the radio until you get a
    > >> null which will let you know the orientation of the ferrite rod. Then
    > >> you can use the edge of the radio to indicate the direction to the
    > >> station. Place it on top of a universal plotting sheet to use as a
    > >> compass rose placed on a table or nav station desk and rotate the
    > >> radio to get a null. You may want to make a calibration table for it.
    > >> Don't worry about the lack of a sense antenna which are really only
    > >> needed by an ADF since a human can easily determine which is the
    > >> correct bearing, the 180 degree ambiguity, which is a big problem for
    > >> an ADF, is not a problem for a human.
    >
    > >> �gl
    >
    > >> On Dec 4, 11:48 am, Bruce Hamilton  wrote:
    > >> > If GPS goes dark, Jeremy will be in a great position to negotiate a
    > >> salary
    > >> > raise.
    >
    > >> > �I had great hope for e-loran as going to a single system with no
    > >> redundancy
    > >> > seems risky at best. Even when Loran C coverage was poor, even the
    > >> > information from a single chain would give you something to work with.
    > >> In
    > >> > the middle of Lake Superior, coverage was always spotty, and on the East
    > >> > Coast of Canada we would often be on a single chain only 50 miles off
    > >> the
    > >> > coast.
    >
    > >> > Jeremy, do you still have a working RDF? �I used them on aircraft all
    > >> the
    > >> > time, but must admit the one on the first ship I was on was not often
    > >> used
    > >> > and this was pre-gps. I have a working portable (Ray Jefferson) RDF that
    > >> I
    > >> > am going to try in a friend's boat. It is a pity that the technology got
    > >> > left behind in the GPS age as the modern RDF's are apparently very good
    > >> and
    > >> > very quick. The signal from the multiple antennas is instantly processed
    > >> and
    > >> > you get an bearing read out. �The Canadian Coast Guard use them to get
    > >> > instant fixes from distress signals in pre-GMDSS days. They have remote
    > >> > stations they use to get a cross bearings from. No GPS required.
    >
    > >> > I know we have some commercial air pilots on the list and was wondering
    > >> if
    > >> > they thought an aircraft RDF unit could be easily mounted on a boat. The
    > >> > aircraft industry seems to be the only ones making small units these
    > >> days.
    > >> > I might go ocean cruising with a friend who is presently re-fitting his
    > >> > boat, and I am a big fan of redundancy, and thought this might be a
    > >> workable
    > >> > solution.
    >
    > >> > A fine page of old RDF units <
    > >>http://www.angelfire.com/space/proto57/rdf.html>
    >
    > >> �> On Fri, Dec 4, 2009 at 8:09 AM,  wrote:
    > >> > > �I read the following on a maritime forum site. �Looks like LORAN-C
    > >> > > systems run by the US will be shut down sooner than we thought.
    > >> > > -----------------------------
    > >> > > The US Coast Guard released an internal message advising of the
    > >> imminent
    > >> > > termination of the long range aid to navigation Loran-C. Current plans
    > >> call
    > >> > > for the termination process to commence on 4 January 2010. The process
    > >> is
    > >> �> > expected to take several months. ALCOAST 675/09<
    > >>http://www.uscg.mil/announcements/alcoast/675-09_alcoast.txt>(11/25/09).
    > >> > > *Note: This will mark the end of an era that started during World War
    > >> II.
    > >> > > The Loran system has improved greatly over the years and was on the
    > >> edge of
    > >> > > yet another advance: to enhanced Loran (eLoran). It is unclear how
    > >> other
    > >> > > nations, which operate their own independent Loran-C systems, will
    > >> react to
    > >> > > this development. *
    > >> �> > Courtesy: Bryant�s Maritime Blog � 1 December 2009<
    > >>http://bryantsmaritimeblog.blogspot.com/2009/12/bryants-maritime-blog..>
    > >> > > ------------------------------
    >
    > >> > > Not that this will affect many large ships. �My ship hasn't had LORAN
    > >> > > capabilities since the antenna broke 3 years ago and the captain was
    > >> too
    > >> > > afraid to order a new antenna. �Most merchant ships are utterly
    > >> dependent on
    > >> > > GPS at this point, and would have a tough time remembering how to use
    > >> the
    > >> > > sextant if it came down to that point. �It will only get worse when
    > >> the
    > >> > > younger generations take command, having never known a time without
    > >> GPS.
    >
    > >> > > JCA
    >
    > >> > > --
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    > >> 
    >
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    > > �--
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    >
    
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