The AM Forum

Some good pics and info.

Scroll down below the map of the US.

The station call signs that are highlighted in red can be clicked on.

The pics that show up are thumbnails and can be clicked on also for full size and resolution.

I picked up some good info. Some of the comments are pretty funny.

                                                      Enjoy,  D.


                           http://www.kkbc.com/projects.htm

I would love to see a picture of that parking lot after the tower takes a good hit to see if the paving explodes.

Dark Thoughts.... :o

 It would be interesting...Scroll down for lightning vs. concrete explosion on link below.

            
 http://forums.mikeholt.com/showthread.php?t=111891  
                    
                  

I would have put a layer of sand or small rock between the radials and paving.

Interesting pix. They have a local (to me) station on there.

http://www.kkbc.com/wmbg.htm

I'm starting to drool, seeing something done right and such nice workmanship

Fred

All that copper and high power gear is eye candy  ;)

As you read the stories you find a lot of thier work is undoing botched contractor work. Copper theft is another big issue.

It looks like hard work but interesting in that every site is a new challange.
I wonder what changes in propagation have been seen before and after these boys do a job.    ??
                              D.

that looks like kevin kidd's work.

I was right (now that I have looked at the web site) AM Ground Systems. 

That website is a great place to look at AM ground construction.   That first photo looked familiar and now I realize I saw it a year or three ago.   If you really want to do your 160 m. ground right, do what they do (or hire them hi hi). 

yeah, I found that looking for info on am BCL grounding, and so far I haven't found better documented case by case work out there.

the one "attaboy letter" he posted, the GM claims that that the stations coverage just about doubled after they put in the new radial system.

There's also a excellent story  on one of the station job threads about how someone in the past had tried to use non-copper as radials and tower grounds and how useless and rusted out it was. I was reminded of the recent thread on here about using galvanized wire and such.

my system I put in just last year is all garbage now save for the 2 connections I silver soldered, every mechanical clamp connection is crap. this time it's getting silver brazed together back to the service connection going past that right to the future 160 meter vertical T feedpoint.

I'm sure my half assed effort last year is what caused most my electrical problems during operating season. Never again.

I'd like to know where he gets the copper mesh.

Yep Derb, many hams try to save a few bucks and do radials on the cheap.  It never pays off in the end. If you are planning on staying put for several years it pays to spend the bucks and go with copper.   Many hams can't deal with the idea of spending hundreds of dollars on wire then laying it on the ground.  They have the signals to show for it. 

If it makes you feel better saving money has been tried by the pros.  I heard a story a few years ago that at one time, WOR 710 tried aluminum wire for radials and that experiment ended after a few months with disappointing results.  The Al didn't hold up well in the ground.

Rob

WOR is in a salt marsh so its no wonder Al didnt work.

Several AM stations who were losing coverage due to the 128 copper radials disintergrating and not being able to lay new copper due to development received FCC permission to go with elevated radials. They then had to reduce power to conform to the original POP results.  Lots of stuff on Google.  One local station uses the metal roof of the 4 story building the tower sits on and gets out real well.

Carl
KM1H

It would seem an investment in a properly engineered ground/radial system might off set or even pay for it self over time.
 If the upgrade / repair results in having to reduce power out for the same TX coverage. Reduced electric bills ( NORTH EAST electric bills!  :P  ), reduced load on the finals and related equip. and fewer service calls ( in theory ).
I'm sure this is part of how station GM's are sold on Grnd. upgrades.
A symetrical or at least predictable prop. pattern has to help target expensive advertising also I guess...
(  geeze, I sound like a salesman  8)  ).

I'de be curious as to the material cost alone.

                                     Blah blah blah,   D.
                                             

I agree that it can get a little pricey to do it right, but look at the results.
The screen is only needed close to the tower, as the pic shows a couple posts down from the top.

Here's a place that sells mesh: 

http://www.darbywiremesh.com/index.html

There's another thread on AMFONE where OPCOM is considering using plastic coated welded fencing. Might be a substitute for the real thing for the near field requirement.

Fred

A source for copper grounding strap and supplies is from a Polyphaser distributor.

http://www.polyphaser.com/products/prod/gnd/acc/

Any guesses how many feet square the screen is at the base of the tower in the pic about third post down?
30' X 30' ????

Fred

That's a great site Steve ;D ;D Loved looking at the pics. I would like that kind of work but I do not like to climb towers. Of course I'm too old now, but if I could, I wouldn't!!

<<Here's a place that sells mesh:  >>

unfortunately it looks like another one of these places where you have to request a quote.  I hate it when they do that.   ???   I just move right along my merry way...

I've heard conflicting things about mesh.  I heard you can get these eddy currents that somehow compromise the performance of the ground system.  Sure looks like it ought to work great especially close in where you can have all that surface area for braising the wire.  I'd put it down on gravel so as to not start a fire and throw more gravel on top of it when done.

I like how the 5/8 copper pipe and couplings are utilized. ( relatively cheap and available )
They even incorporated existing copper plumbing ground material into thier new work.
I guess with skin effect, RF sees that pipe as pretty "wide" electrically.

I like these guys.


http://www.gacopper.com/index.html

I dont see how copper mesh maintains its effectiveness if all the crossing points arent bonded. After a while you have a million diodes.

The welded and galvanized 2x4" mesh on the other site is what I had used except it had been plastic dipped; it came in 4' x 50' rolls. Their 24" x 100' rolls would be ideal and the weight is low. Cut in half or thirds for 80M.

Carl

Some of the mesh sheets I've seen are actually an "expanded lath" and have no junction points except the perimeter. Alternating slits are punched/cut into a sheet and pulled apart like paper dolls. Aluminum lath is made the same way for mud work in tile and masonry work.
Interesting observation re. the diode effect.
The chicken wire style copper mats would be an issue I guess.

High performance on  80 / 160 can be some work I guess!
                                                                                              
                                                                                 D.

I'm not sure that mesh is any better than having many radials up near the tower, something like the normal 120 radials 1/4λ or more, but maybe twice or 4 times that many near the tower base, using short radials perhaps 50 ft. long or less.

I have read in several engineering books that it does absolutely no good to tie the far ends of the radials together with a perimeter wire; it's a waste of copper.  So wouldn't the same principle apply in close proximity to the tower base, regarding the wire in the mesh that does not run out radially from the common point?  The best way to "fatten" the radials would be to add more of them.  Maybe one perimeter wire that bonds all the short radials to the main ones would serve a purpose, since that would give the current induced in the short ones somewhere to "go" besides into the lossy earth.

The dawg  house (inside the fence near the tower) at KKBC looks amazingly like the one I just built.

(http://www.kkbc.com/wyhl0020.jpg)

(http://www.kkbc.com/wyhl0009.jpg)

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/Completed.jpg)

When we were building a 6 tower AM directional antenna system here in Cleveland, back in 1999, I was asking the tower crew if they used copper mesh under the tower bases any more.  The said they found no measurable difference between using a 24' x 24' mesh at the tower base or simply attaching the 120 radials to the copper strapping secured around the tower base.

But I found out another interesting point.  At that installation we used half wave lengths of #10 wire instead of quarter wave lengths for the radials.  The increase in efficiency was just a few percentage points, but for AM broadcast, even a 5% difference could help.

As for ham radio though, unless you wanted to squeeze all the efficiency you could out of a Marconi type vertical radiator (QRP use?), its doubtful you could even perceive any difference between 1/4 wavelength and 1/2 wavelength buried radials.

There is a company that sells and installs above ground radial systems for AM broadcast towers that claims that 6 quarter wave above ground radials result in effectively the same field strength at one kilometer as a system using 120 buried quarter wave radials.  The disadvantage of above ground radials is that you do not have a nice dissipation system for the lightning strikes.

Also, when we built that system 11 years ago, we installed static dissipators at the top of each tower (6 towers @ 260' each).  The dissipators are made of a cage of metal rods, each having hundreds of sharp pointed spikes about 3 inches long attached.  In 11 years, we have never had any evidence that any of the towers has ever been struck by lightning.

.....stuff we learned as broadcasters that we can use at home!

73
Ted  W8IXY

What station was that, Ted?

Usually translates "outta my league" for price............prolly $100's of dineros.
Fred

This will be my solution in Fall.......can't financially pull anything right now.

Fred

Hi Bud,

That was the complete rebuild of what was then WRMR, now WKNR (and WJW for many years before that).  We took it from 10Kw days to 50Kw days, and had to stay at 5Kw nights.

Ted  W8IXY

That is for ground wave coverage.  I wonder if there is any data on how buried vs above-ground radials compare for skywave.  I seem to recall some mention that buried radials are more effective for skywave, but have no statistics to back that up.

For 160, hams are primarily interested in skywave coverage while for AM broadcasters, they are all but entirely interested in local ground wave.  Even the historic clear channel stations do little, if anything at all nowadays to promote their night time skywave "secondary" coverage.



Damn, I hate to hear when old time broadcast stations give up their historic 3-letter callsigns and adopt some hum-drum 4-letter combination. Usually happens when the station is sold and new corporate types come in and take over the operation.

I think the ends get soldered or braised to a wire when you have two or more phased towers and a wire gets run halfway between them in a straight line and each tower's radials get bonded to it where they overlap. 

I like to remember that the very first AM bc station was KDKA, a K call, East of the Mississippi  :D

If I am not mistaken WABC used to be WJZ.   :(

You're right Ted there is a lot about AM bc antennas that can be used by hams on 160.  A few years ago I signed up to one of the broadcast email reflectors purely for that purpose.  I participated for a few years asking questions every now and then.  I was sort of tolerated because I used to work in broadcasting years ago.  The guys there were very helpful.  Of course there were a lot of topics I was uninterested in, like STLs, talk show caller management software, tower lamp status monitoring, FM and TV but when they were discussing feedlines, ground systems, mics, ATUs...RF stuff on medium wave it was interesting. 

After a couple of years I figured I had learned everything I was going to get from an email list and signed off.

I always hope if I get a lighting hit my ground system will help dissipate it but I hope I never find out.  I do have a big static charge drain choke I got out of a Kintronic ATU.  It is about 18" long and 2 or 2.5" o.d. and wound with no. 22 enamel wire.  Probably about 230 feet of wire on this thing.  I have it in series between the 75 m. vertical and ground. 

Rob

I am interested in the hammock or vertical T antenna for 160 because it is omnidirectional and has a skywave component in addition to a ground wave. The objectives of the BC band and ham 160 meter operation do not coincide 100%.  I'm going to start out with this one and see how it does.

I dont think it will match up to a antenna like Don's in any way but I do think it will get out and fit on my lot.

BC sites are chosen for soil conductivity and have lots bought in if needed. Hams rarely have that option unless they are in a salt water marsh or in the farm belt.

I noticed a HUGE improvement when going from 120 random length radials (50-150' to fit the property boundries at a prior QTH) for a 160M shunt fed tower to four 4' x 50'  lengths of the galvanized and welded mesh added at the base.  The radials were tied into another field for a pair of 80M verticals so both bands benefitted.

My ground there was a low conductivity sandy soil with a high water table that was ineffective. Real black soil was only 3-4" thick. Far field in a few directions was over about a mile of fresh water swamp but it wasnt until I put down the mesh and tied the fields together that I started kicking serious ass on both bands.

Carl
KM1H

I don't know how it would make any difference. The radial system only addresses losses in the nearfield. The ultimate pattern is form at many wavelengths, well beyond the radials.

Only if the above ground radials radiate and create some higher angle stuff would they make any difference for skywave (high angle) propagation. After all, eve the very low angle (so call groundwave) becomes skywave eventually.   ;D

What is the alleged magic about 42-43 ft. for top loaded 160m verticals?  I see those figures used frequently in articles and descriptions. I say get it up as high as possible, but still survive windstorms.

To really make the end supports look vintage cool, find a pair of old triangular shaped self-supporting farm windmill towers. The coat of rust would add to the authenticity.  :)

As you reduce ground losses in the radial field the angle of radiation decreases and contains more power) at the real low angles that are important to DXers. Verticals are also great daytime antennas on 80/160, ground wave is not all at zero degrees.

Elevated radials are very effective over poor ground. Now the radials can be considered part of the antenna and low loss high Q elements. There will naturally be some current imbalance which is why a sleeve balun is necessary to eliminate coax outer shield radiation. Compare that to the detuning effect of on or in ground radials which is like paralleling each wire with a resistor. Watch the pure R part of either process as you increase the # of radials. For 160M I saw no improvement above 32 elevated radials at this QTH; I tried 64 and then moved 32 to the second vertical. I have 6-12" of thick black soil but then it hits solid rock or turns to a bony sand/clay mix. Solid rock ranges from 6 to about 24" down on this hilltop so the conductivity pretty much sucks.

There is no way I would ever consider four 128 on ground radial fields for each band as I progress on the 4 Square arrays.

Carl

I used to listen to Alan Freed (who supposedly coined the term "rock and roll") on WJW 850 when I was a kid in Cleveland.  Alan got his start in Akron and then Cleveland before moving to the "big time" in NYC. Still remember reading about the riot at Freed's  "Moon-dog Ball", maybe the first rock concert of its kind.  The movie "American Hot Wax" does a pretty good job of characterizing the guy in his NYC days.  IMHO, its worth watching. 

I listened to him as soon as he hit WINS 1010 and still have programs from his R&R shows in the NYC area. His crash to oblivion was very sad.

Carl

Sadly, nothing much was left over from the WJW, Cleveland days by the mid 70's, when I spent my first incarnation at that station.  About the only thing I found intact was their original 167 mHz STL transmitter.  I had remembered seeing that up and running from the WJW mobile studio back in my grade school days in the 50's.  I "salvaged" it, and it now resides intact in the Cleveland Broadcast Museum.  It used a serrasoid type exciter (same as broadcast band FM) except it was tuned for 167 mHz, and not 88-108.  There was a 50 watt PA and several huge power supplies used to fire it up.

WJW was a Storer station in the 50's and 60's.  When it was sold, and separated from the TV station, the radio station originally kept the 3 letter call, and the TV station became WJKW.  In 1985, when the radio was sold again, WJW went back to the TV station, and the radio became WRMR.

When we rebuilt the station, from ground system up, back in 1999, the signal at 50kw daytime, 4 towers aimed primarily south, covered most of Ohio.  If you are in Dayton, punch up 850 and give it a listen (daytime).  If you punch up Radio-Locator, you can see the coverage and pattern shapes. 

When the owner sold the 1100 signal (50kw, non-DA), and got the 850 signal plus cash, I told him we could take the 850 signal to 50kw days, and we did it.  I left there shortly after we cranked up the power (ownership change stuff again), but several years ago, after several more ownership changes, the present owners called me back and asked if I'd be interested in doing contract work there.  The deal was a good one, and it kind of felt like going home.  The great thing about that was, since we built it right the first time, the transmitters and antenna system had not drifted at all, and to this day, the coverage is unchanged from the original tune-up in 1999.

For once in my life (thanks Tony Bennett and Stevie Wonder) it was great to take care of an AM antenna system that still works as it was installed 11 years ago.   

I also was thinking that if one wanted a great 160 meter antenna, you could install a 5/8 wave tower, with appropriate ground system, and use the lower lobe from that tower for great groundwave and long DX, and the higher lobe would probably work well for closer in stuff.  But on 75 and above, the vertical radiation pattern would include several "holes" that could prove difficult if the station you wanted to work was inside one of those vertical angle nulls.  It would probably not work well for NVIS close in stuff.

The best AM broadcast antenna I ever worked with was the full wave Franklin vertical that was used on 1100 here in Cleveland from the mid 50's to the mid 70's.  Those two half waves in phase (collinear) produced a wickedly strong ground wave, and the exceptionally low angle of radiation was great for 300+ miles out.

Regarding "resonant" antennas, another facility here in Cleveland used three towers on 1420.  None of those towers are "resonant" at 1420, two being about 400' and one about 200', but with a good radial system (buried), and appropriate matching at the base, those towers also radiate a very good groundwave, and have the vertical angle nulls in the right places to protect several co-channel stations.  If you match the antenna to the feedline at the feed point, most anything will radiate well.  Then the actual electrical length of the radiator will determine at what angle you will radiate the maximum signal.

73

Ted  W8IXY

I've wondered about 180 to 210 degree towers on 160 myself.  Of course they'd be so tall they'd have to be lamped and all that so they're not an option for almost all hams.  There's some idea amongst the 160 m. dx crowd that they do not work well for skywave and 90 degrees is better.   I have not understood that.

The 1100 Franklin must have been extremely tall Ted.  How was it fed, with OWL?  The one at KFBK on I think 1520 is pretty darn tall and fed with unbalanced OWL.   That one is two phased Franklins for a bidirectional pattern north and south I believe. 

Rob

Ted, I remember the KYW franklin antenna.  Got a tour through the facility in the early '60's.  Can't remember the type of 50 KW tx they were using anymore, but do remember there was a vertical wire dropped from one of the guys of the tower which was used as a second element making the signal somewhat directional with a slight null to the north.  I think limiting the signal over Ontario....so I was told.  Unusual set-up.

Way back when, 1420, WHK, had top loaded self supporting towers.  Seems they were replaced with guyed towers in the early '60's. 

Yeah! BADASS! ( I'm serious.)  8) I know where at least one of those are - I'm sure they would love to get rid of it. - not that I could do it myself mind you, but I know people that could take em down for me.

the trees I have here are just crap for antennas - I'm going to have to go with masts anyways.

I think the manufacturer or one of them at least, was Vesto.  They made them for windmills but they also advertised in the ARRL handbooks back in the 1950s for hams.   I believe they were four sided.   one side had a ladder you could climb.  Can't remember how high they'd go but I think 50 feet was one height.  Now that's a tower that would not blow over.  The base of the 50 footer was probably 15 to 20 feet on a side and they went up to a point.   If it ever folded over you could probably kiss everything else goodbye too. 

Rob

That started a few decades ago when a successful DXpedition vertical was developed. Nothing magic about the size, just a convenient height to ship broken down and survive harsh weather. It still is ineffecient compared to a full quarter wave. On 80M the 42' is very effective with minimal loss.

Carl

Windcharger had them to 100', those were the most popular farm towers that went to many hams when rural electrification went thru.

Carl

http://www.fieldlines.com/board/index.php/topic,127842.html


these towers are back in some demand from alt energy peoples wanting to use them as they were made to be used.

A pair of those 45' Windchargers would be perfect for Derb's hammock antenna.

Windcharger also made AM broadcast towers.  I  recall seeing them advertised in some of the mid 1950's ARRL handbooks. The oldest local AM station in this immediate area went on the air around 1940.  Their tower is a Windcharger.  It is a uniform cross sectional tower with a tapered base and base-plate to accommodate the insulator.  Instead of using steel tubing or solid rod, all the pieces are angle stock.

take a look at this. windmill pr0n. kool. notice the radio ads on many of the tailfins .

http://www.wincharger.com/

I have no doubt that my HOA would not allow these as antenna masts but would as generators. It's all in the political correctness. Alt -Energy in style right now. Radio, not so much.

Derb, you have an HOA?  That's too bad.  Don't be so sure about the alt. energy -- a lot of these control freak HOAs are just as down on windmills as they are anything else.  It's another case of people with nothing to do so they make controlling everything in the HOA their mission in life.  There have been cases of people not being allowed to fly US flags even.