[Milsurplus] NDB's and LOM's

[Mark K3MSB]

 Hi Charlie

Thanks for sharing.    North Dakota currently has only two operational
NDBs:  GF (345 - "Hiser") in Grand Forks and DI (353 - "Noson") in
Dickinson.

Currently is an apt word as DI (353) is due to go dark on the 25th -- 4
days from now.     CT, RI, UT, And NV have no operational NDBs.

The NDB Close to Spartanburg Airport -- Would that have been FRT (248) ?

There are still two active NDBs in Greenville SC --  GM (521) which I hear
quite a lot and GY (338) which I have yet to hear.

73 Mark K3MSB

On Sun, Feb 21, 2021 at 11:27 AM CL in NC via Milsurplus <
milsurplus at mailman.qth.net> wrote:

> I used to maintain these for the FAA many years ago. Since I was the only
> ham at the three different field offices I worked at over the years, I also
> got all the SWL reports, or would that be LWL reports, and had a nice
> certificate for those that sent a report.  There were still many on the air
> back then, but few requests for confirmations, until no requests for
> confirmations.  I think anyone interested has passed on, or they did not
> bother to send a signal report.  I am sure most field offices rotary filed
> them, but I liked to answer them.  Over the years, I had stations that ran
> 400 watts to 250 ft and down, tower heights, or as low as 25 watts to a
> simple 50 foot vertical wire with single or triple top hat wire.  I had one
> station I maintained for a local airport, a commercially manufactured
> product that contained two 25 att transmitters 1KC apart.  Instead of
> having a circuit, as most did, that generated a 1020Hz or 400 Hz ID signal,
> it would key the other transmitter that was 1KC off to generate a beat
> note.  For some reason, the most received NDB I ever had was at Greenville,
> SC next to the municipal baseball field which was situated right next to a
> 4 lane highway, and the transmitter was only 25 watts with a 50 ft wire
> vertical with 50ft single wire top hat.  Of course the counterpoise on all
> stations was extensive, 160 radials of #6 solid copper minimum, the length
> determined by the plot size.  There were some 1KW stations left before I
> retired, I believe in Alaska was the last, but places like Montana and ND
> had them at one time.  The NDB that still exist for the most part used to
> be the Adcock directional beacon, that sent the letter A or N depending on
> the quadrant you were in, and an on course indications was achieved when
> the A and N superimposed on each other and you got a steady tone.  Many of
> those stations were downgraded to NDBs by just cutting off the part of the
> transmitter that generated the other signals sent to the ring of 4 towers
> around a central tower, and then those other 4 towers were removed leaving
> only the center one.  NDB's and LOM's are basically the same transmitter,
> but the LOM, Locator Outer Marker, uses a 400Hz ID tone with normally a 2
> letter ID sent, 3 letters are usually NDB's, and were co-located with the
> 75MC Outer Marker transmitter.  In the late 90's we removed the top 50 feet
> of one of the beacon towers because the ring transformer that coupled AC to
> the obstruction light circuit failed and the FAA was too cheap to buy a
> replacement, so the remaining 195 feet did not need an OB lamp even though
> from the top of the tower you could almost spit to the Spartanburg
> Airport.  All of this stuff is being shutdown as more and more navigation
> in put in the GPS basket, but the FAA has come to realize the danger in
> that, and has decided to leave certain VOR's on the air.  Air traffic
> control at first consisted of bon fires on the tops of hills, the radio
> beacon was the next improvement and have been with us since the early
> 30's.  One of the Adcock site style transmitters was on the cover of ER
> Magazine several months back.  I live in an area with frequent power
> outages, trees, wind, ice storms, and one of the best times to hear those
> stations is when this occurs.  I listen on a Bendix RDF, and ever during
> the day, you can hear many signals when all the AC power line crap goes
> away.  Judging by the fact places like ND or AK only had a couple of the
> 1000 watters, I would guess that in the air, reception was several hundred
> to a thousand miles.  The remaining beacons can be found on this site:
> https://www.dxinfocentre.com/ndb.htm
>
> Charlie, W4MEC in NC
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