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Commercial Radio Antennas - Please keep discussion related to professional, commercially used antennas and antenna systems for the two-way radio industry. Topics for the use of these antennas on amateur bands are accepted here.

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Old 02-01-2017, 2:11 PM
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Default A Tower Mystery- can anyone help me?

On a recent work trip east, I was in Annapolis Maryland. There, I took the opportunity to visit the former site of Naval radio station NSS. The station was located on Greenbury Point, near the Naval Academy- at the mouth of the Severn River. The site is part of Naval Station Annapolis, and it still retains 3 of its the original Effile Towers, dating back to the 1930's. The Goliath Antenna array, transmitter, Helix House- they are all long gone, and the area is closed to civilians.
.

But three of those 600 foot towers remain, and to me they are magnificent examples of a by-gone era-- and I was fortunate to be able to explore the Point.
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My posting here is to see if anyone can answer my curiosity about something I have no idea as to what they are. These appear to be large concrete weights, standing about 10 feet high, on steel pedestals, centre'd under the towers. Two thin cables extend upward to the ~150 foot level. They don't appear to do anything- and none of my contacts has any idea what they are.
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Anyone hazard a guess??
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.......................................CF
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Last edited by Coyote-Frostbyte; 02-01-2017 at 2:17 PM..
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Old 02-01-2017, 2:25 PM
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I would suspect the concrete weights are putting more down force on the tower to keep it from going over.

Normally when we add more equipment that places more danger of the tower toppling over, a retaining wall is built around the base of the tower and backfilled with crushed stone. This places more weight on the tower foundation located underground. Typically there's a large concrete pad buried under the tower and the additional stone helps weight the tower down.

Since this appears to be a large tower and the cost of placing a retaining wall around the tower might be high, it might be cheaper to suspend concrete weights from the centre of the tower.
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Old 02-01-2017, 2:29 PM
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Ten-ton weights suspended from the towers helped keep antennas taut during windstorms. When ice formed on the cables in winter, technicians melted it off by turning up the current from 600 amperes to 1,000.

Greenbury Point Towers | Towers to beckon no more - tribunedigital-baltimoresun
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Old 02-01-2017, 2:41 PM
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That makes more sense. I'll be there's a pully arrangement at the top of the tower.
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Old 02-01-2017, 3:00 PM
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Very interesting, thank you for the link to the article.
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Old 02-01-2017, 4:43 PM
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So, in the 40's they were capable of transmitting a signal as far away as Ireland with their (compared to today) limited technology. And with todays technology we still cant keep a decent cell phone reception in rural areas. The people of that generation were amazing engineers. And without computers I might add.
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Old 02-05-2017, 3:11 PM
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Hey Guys--
.
You all were right- ...
............. this block of concrete has to do with stabilizing the tower. One of our engineers called a contact with the Navy, some one familiar with enormous antenna arrays (station NAA in this case)- and they quickly said this was a counter weight. There was a cable originally run up thru the top of the tower, over a sheave wheel, to the insulators of a curtain array. These curtains, or Panels, as they call them, weight tonnes; and during ice and wind storms, can suffer untold damage- the additional weight on the arrays raises the concrete blocks, lowering the stress on the antenna. The weight in the picture, we were told, probably dates to an earlier period before NSS was redesigned with its huge Goliath antenna- that was in the 1960's- these Eiffel towers date to the 1930's, and have supported other arrays over many years.....
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And, speaking of many years ago; as a graduate student I got to visit NSS shortly before it was decommissioned. It was one radio experience I will never forget- you could literally walk and climb about *Inside* the transmitter- feeling every bit like a mouse exploring the inside of a high power'd amplifier. The Helix House, where the matching coils were located was something I am sure mirror'd Tesla's finest laboratory.
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I've posted a final photo, showing the top section of the tower, with its copper Faraday shields. Just looking at the catwalks and ladders gives me vertigo- I can't imagine what it was (still is) like to change the warning lights.... I was offer'd (jokingly) a chance to climb one- Simple answer: "Not on your Life!"
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................................CF
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Old 02-06-2017, 9:28 AM
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The top of one of the towers is occupied by 2 (or 3?) VHF 4 bay folded dipoles, an Adcock type ADF array and a UHF 'stationmaster type' all in use by USCG sector Maryland Capital Region.

Below them down to the mid tower level are some microwave dishes, panel antennas and unknown "stationmaster types'. I think Anne Arundel County and probably cell phone systems are the occupiers of this mid level of the tower...perhaps somebody can confirm or correct this.

About 5 years ago, there was a construction project to bring fiber-optic cable out to feed this tower on Greenbury Point which I think was to supply the Coast Guard's radios which appeared once the fiber optic was in place.

I wonder if those nice photos that Coyote-Frostbyte posted are from the visit he mentioned years ago, because the tower looks a little rusty and unkempt which is not the case now...all three towers seem to be maintained and certainly the Northwest tower that hosts all of the land mobile antennas is in very good shape.
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Old 02-06-2017, 12:22 PM
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I took those photo’s last month. I too, was taken slightly aback by the appearance of the towers- they look a tad shabby, paint wise- but they are extremely sturdy (to my untrained eye) - and the rust appears only superficial. They have endured that Point for over 80 years and probably will be there a lot longer…. I was told they are a sort of National Historic Site- which affords them some sort of protection. That may be easy to give to an historic house but 600 foot antennas may not be so “preservable,’ especially for their new owners.
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Anne Arundel County owns the towers, but the land is the Navy’s. Only one of the three towers is currently used- which makes me wonder what may be the long term fate of the other two. Currently, Greenbury Point is getting a facelift- new trees are being planted over the areas where the former buildings stood. I was told the massive concrete base for the enormous 1200 foot central tower is still there, but that would now place it out in the middle of a cat brier jungle. January or no, no one of us had any desire to chance the ticks and Lyme Disease (it was a very mild Maryland winter day- the high near 60- a good day for ticks)-- or undergo the mutilation of a briar patch in order to see it.
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We paused awhile to comment on the antennas that festoon the northwest tower (supposedly that was what we were there for- to look at the towers, after all…) each one of us offering suggestions as to what they all are, individually and collectively. In my first pictures you can just make out part of the equipment huts located at the tower’s base.
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But in the end we were out there to walk the Point, taking in the Chesapeake Bay, the ships,the Eastern shore view- the Severn River- and, of course!- to bathe in the ambiance of those towers- as only a bunch of geeky engineers and physicists could do……(smiles )
.
.
………………………………CF
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Old 02-06-2017, 12:40 PM
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Quote:
Originally Posted by clbsquared View Post
So, in the 40's they were capable of transmitting a signal as far away as Ireland with their (compared to today) limited technology. And with todays technology we still cant keep a decent cell phone reception in rural areas. The people of that generation were amazing engineers. And without computers I might add.
Bandwidth versus frequency. To meet the desires of high capacity and data systems carriers moved to higher frequencies which limited effectiveness to line of sight. Carriers won't build coverage to areas where they won't make money doing so (such as areas with a low population density). A good example of this is the I-10/I-20 corridor's in West Texas. As soon as you get out of populated areas or off the interstate the coverage drops to next to nothing due to lack of infrastructure supporting the sectors. No point in spending the money on the infrastructure that will never return the investment.
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Old 02-06-2017, 5:58 PM
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With all do respect. My point was, they designed a system almost a hundred years ago that could talk to "no man's land". That's a pretty impressive design.

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Old 02-06-2017, 6:07 PM
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Quote:
Originally Posted by clbsquared View Post
With all do respect. My point was, they designed a system almost a hundred years ago that could talk to "no man's land". That's a pretty impressive design.

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It is an impressive design, however one that cannot be compared to the cellular network.

Two very different things.
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Old 02-06-2017, 6:43 PM
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Oh for heaven's sake. I know they're two totally different things. My original comment wasn't intended to be taken literally. It was meant to convey rhetorical irony. To garner a laugh or two. You know? Like " they could talk half way around the country a hundred years ago with a two way radio, but today you can't walk 500 feet without losing your cell phone signal". Haha!!

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Old 02-07-2017, 12:52 AM
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I was smiling when I read the bandwidth issue, above. And I will be the first to say there is little connection here between the discussion of VLF radio communications and high speed cellular data systems. Clbsquared, I for one, however, appreciated what you were saying…. Living and working in the sagebrush hills of New Mexico I have often cursed ‘cel qualities….
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One of the things I find interesting about VLF is the tremendously narrow bandwidth restrictions imposed by the extremely small (in relation to wavelength) antenna sizes. In the case of NSS, we were talking an 8 mile long wave crammed into a tiny top-load vertical of only 1200 feet (Only 1200 feet!…laughing!) The Q of the loading circuit was so sharp that the effective bandwidth was limit’d to something like a 25 Hz- that is like a maximum CW speed of 50-60 wpm (and yes I know, NSS used FSK, but the narrow bandwidth still remains a major limiting factor for anything E/VLF.)
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I loved the low frequencies, and as a grad student my thesis was VLF related . One project I did as a teaching assistant was for an undergrad class. I assemble a VLF station, using DSB (double sideband suppressed carrier voice)- operating into an extremely high Q antenna. By offsetting the frequency on either side of the antenna’s centre frequency, it would produce a single sideband signal- upper, or lower, --- the antenna alone was all that was necessary to effectively eliminate the other sideband.
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Since I have launch'd off into the esoteric, I will close with something about NSS. It was constructed back during World War One, to insure the US could maintain contact with Europe should the submarine telegraph cables be cut. Back in those days of spark and alternators, the range from what we’d consider from those oh-so primitive transmitters and receivers, to me, rival anything used by NASA in deep space exploration today.
.

.
…………………………….CF

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Old 02-07-2017, 1:07 AM
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Quote:
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Oh for heaven's sake. I know they're two totally different things. My original comment wasn't intended to be taken literally. It was meant to convey rhetorical irony. To garner a laugh or two. You know? Like " they could talk half way around the country a hundred years ago with a two way radio, but today you can't walk 500 feet without losing your cell phone signal". Haha!!

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Sorry man your comment fell on deaf ears.


Last edited by toastycookies; 02-07-2017 at 1:15 AM.. Reason: God Damn I Love Corn.
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Old 02-07-2017, 5:59 AM
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Sorry man your comment fell on deaf ears.

So uhh.. is that corn GMO or Organic?

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Old 02-23-2017, 9:08 AM
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Smile Cool Photo's !

Great photo's very interesting !
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Old 02-23-2017, 11:43 AM
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Those old towers fill me with awe. The space between the tower legs I can only estimate- 80' ?.. there is space under them for a good sized house, with plenty of room for a yard. Their construction with rivet'd girders, scary open ladders and walkways- all speak from a forgotten era, -- I am fascinated by radio history.
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I will be visiting the Naval Academy as a guest lecture'r later this year. At that time I have been promised an opportunity to go out to the Point and climb one of those towers-- (laughing- and again, the answer is still "NO !!... )
I have also been assured that, declining this great chance to see, first hand- the huge sheave wheel, the Faraday shields, the final 'spiral stair case," and other wonders at the top of the towers, that I will be shown where to look-- from the ground --- thru binoculars!
.
........................CF

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Old 02-24-2017, 8:45 AM
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A few days ago I was watching the movie Midway for about the 50th time and several times during the movie they are sending messages from Pearl Harbor to the task force 900 miles away and then there was the Japanese listening post on Kwajalein intercepting their fake message about the water condensor. So I was thinking in the days before satellites are they using short wave radio and skip and towers like these to communicate with the ships?
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Old 02-24-2017, 11:21 AM
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Yes they did, Tim- use facilities like this to communicate all over the world in the pre-satellite days- and they still do.* These particular towers were used on very low frequencies- subject to far less propagation anomalies than HF- and their last mission with the military was to communicate with submarines submerged on the other side of the world. NSS continued to operate long after the modern space technologies came into use.
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I was told this interesting Cold War tale about NSS. Please bear in mind, I have not verified it, but it has a nice ring to it-
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“…..Long after the Navy stopped using NSS to send encrypted messages to the nuclear submarines, they kept the transmitter operating. They broadcast’d coded messages of all sorts, from minor information to gibberish- knowing the Soviets would devote a lot of effort at decoding them. This was part of President Regan’s plan to have the Soviet Union spend itself into collapse.. And it worked, but programs like the NSS station came with a barb. After the beginning of Detante and the easing of Cold War hostility, the Russians informed us, in no uncertain terms that this encypted NSS business was a serious drain on their intelligence apparatus. They also said that because they knew it could be used to launch a US nuclear strike, even if it was (as they suspected) only sending none-such, it still merit’d as a first strike target for several thermonuclear missiles. Right next door to NSS is the Naval Academy, and the city of Annapolis…..
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………….The transmitter quickly went SK** “
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A urban legend?….. Maybe the Navy guys were putting me on, but it’s a neat story, No?
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Bye the bye- somethings haven’t changed much. You mentioned Kwajalein- I have spent a lot of time on that Atoll…remember the “Star Wars?” missile program- that was a bit before my time- but I and my guys continue out there in more modern versions….. and “Brand-X” listens in………….
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…………………….CF

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._________________________________________________ _
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*Goggle station NAA
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** That is Morse code for “closing station”… very apt here

Last edited by Coyote-Frostbyte; 02-24-2017 at 11:26 AM..
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