Vertical for low bands or not? Need some advice.

[ke7trp]

After Reading the new issue of ER,  I realized the 939 antenna tuner that matches the T368 transmitter, was able to tune an 18 ft vertical.  I realized that I have a vertical and it kinda got me thinking of putting it up.

The vert that I have is from a battle ship.  It has a mounting plate with four huge bolts, a 200 lb ceramic insulator and about 60 some feet of pipe as the mast that gets smaller as it goes up.  Its new, Never used. Army surplus.  I was told it was for a ship or boat.
 
It would be easy to put up.  Either hole with concrete and a plate for mounting.  Or two big hunks of steel beams anchored down.  Two men can Raise this thing. Its bottom heavy the the mast is not that heavy. 


Couple questions:

How would I feed this thing?  Open wire line?

Coax and a matching network at base?

The 939 could tune it I am sure. Might be better options?

I would like to use it on 160, 75 and maybe 40 meter AM portion of bands.

Is this a bad idea in a neighborhood surrounded by homes?  Something tells me that I will probably have horrible luck with interferance with a vert like this. 

Thanks for the lessons.

Clark

[N3DRB The Derb]

howz about some pix of the insulator and base plate? How long is the thing ? never mind, duh. 60 ft is teh ticket for 75.  maybe add a small capacity hat to broaden the band width some at the top.

your issue would be laying out a good radial system. feed it with coax, shield going to yer ground/radial system. operation on any other band than 75 would require a matching unit at the base of the vertical. Operation on 160 would need some top loading.  a 50 ohm match at the base of a 1/4 wave vertical usually means you have excessive ground losses caused by a not good enough radial system.

Generally a match lower than 50 ohms is desirable. actually tuning the matching unit for maximum fire in the wire either with a FS meter or better yet with a rf ammeter is the way to go on any marconi type antenna ( fed against ground ).

[K5UJ]

As you say, there are a few ways of doing this; I'll just describe my setup.  I have a 65' vertical in the back yard for 75 meters, 50' of 3 inch aluminum tube and a 15 foot aluminum stinger bolted to the top.  The whole thing is mounted on a 10 foot 6"x6" pressure treated pine post that's in the ground 3 feet.  The bottom of the tube is on a hinge.  There is a winch at the top of the pine post with a strap on it and a hook that attaches to the tubing so the whole thing can lay on the ground and crank up.  I have only cranked it up once when I put the whole thing up.  It stays vertical.  Cranking it up was a two man operation so I won't crank it down again until I have to make some kind of repair.  It bowed over pretty good but sprang up.  It is made of 30 and 20 foot aluminum tube sections. It is guyed at one point at 31 feet.  It also holds up one end of a low band dipole and a PVC arm at the 50 foot top holds the top of an Inverted L wire 3 feet out from the mast.  This drops down to a radial ring where everything all the feedlines bond to and I can feed the inverted L and the 75 m. vertical.  I feed them with 1/2 inch 50 ohm heliax and for now, tune in the shack but tuning at the feedpoint is preferable for the the unexpected reason that somehow, the antennas react less with other antennas when the tuner is out at the radial ring.  That may just be a site specific thing that won't matter anywhere else, especially if you are fortunate enough to have room to spread antennas out.  

I use mine with ground level radials, 101 of them but they are anywhere from 10 feet long to 120 feet.  Most are 30 to 60 feet.

The 65' vertical on 75 meters certainly makes a difference and is almost the same length as yours so you would probably get a similar result.  Under 1000 miles the dipole and the vertical seem to be the same.  Under 500 miles the dipole takes over.  The huge difference favoring the vertical is with the west coast, stations out in Seattle and such that are 2000 miles away.  I worked a few guys up in the pac northwest running around 250 watts and went from S9 on the dipole to 20 dB over S9 on the vertical.

This was late at night in winter.   Why didn't I use it more?  I probably used the dipole 90% of the time.  It turns out that the vertical is great for transmitting but if you are going to use one, you pretty much have to have some kind of separate low noise rx antenna or your "dx" qsos will be pretty unenjoyable.  The high noise level reception results in those quick signal report type QSOs that for me at least, are not why I'm operating AM.   I personally could not care less where the guy I'm working is located; I'm in this for the fun of ragchewing and want solid armchair copy more than anything else, so I naturally gravitated toward the dipole, but if I can ever get a small rx loop or something similar put up, I may use the vertical more.    

I don't know how yours would play on 160.  It sounds like it can't support any kind of top loading cap hat. or Inverted L type wire hanging off the side so I guess you'd have to put some kind of loading coil at the base.   You can certainly get something like that to work but what I'm trying to say is I have no idea how it would compare to something like an Inverted L.  It might be just as good.

There is one thing you could try that would be superior to a loading coil at the base.  If you could drape a wire across the top between two supports of sufficient height and distance and suspend a drop wire down to the vertical from the center of the horizontal span then you could hang a wire with a trap there and have a top loaded T on 160 that would only function with the trap.   I don't really like traps--they have their own problems so maybe you could do this without the trap and employ some kind of matching network at the base for 75 and 160 meters.  Just brainstorming here.  Anyway, it sounds like an antenna worth trying  even if you wind up using it only on 75.

Rob

[N3DRB The Derb]

check how this guy did his.

http://www.k9ct.us/Photos/Vertical/index.htm

pretty tidy.  But he needs a lot more copper than that 1 little bare 10 gauge round wire he has running ---more like 4 2" straps minimum.

[flintstone mop]

You gotta consider who you are trying to contact. If everyone you want to contact is more than 500 miles from you, then a vertical 65 feet or so, with a good radial system, will be the ticket.
If your working stations closer in then a dipole about 40 feet high would be better and simpler.
A vertical is a lot more complicated. In the tactical commo world, they wanted to deploy something quickly. They weren't looking for 30 over signals and hi-fi audio.

Fred

[k4kyv]

check how this guy did his.

http://www.k9ct.us/Photos/Vertical/index.htm

pretty tidy.  But he needs a lot more copper than that 1 little bare 10 gauge round wire he has running ---more like 4 2" straps minimum.

I hope he doesn't cover the base plate with soil, since he used one of those crappy hammy hambone metal plates that use screws and nuts to hold the radials.  Those screw connections will inevitably corrode, probably work loose, and turn to diodes in a few years.  Brazing with silver alloy is the only way to go, and if his base plate is one of the commercial ones, cheaper too.

I would almost be willing to bet that the screw eyelets at the ends of the radial wires are either crimped in place or soldered with lead/tin (look crimped to me).  In either case, extremely prone to failure in wet unprotected environment.

But at least his radials are neatly laid out.  I clicked the link to AM Systems Ground Company, and one thing that stood out was the way the radials were sloppily laid out at the base of the towers.  Notice radials cross over each other and some of them look like a tangled mess.  Probably doesn't affect performance, but the image would have looked a lot more impressive to potential customers, considering the care they took with the  rest of the job, if they had made sure the radials left the tower in a straight line with uniform spacing between. The base connections to my 120-radial 160m ground system looked a lot neater than that before I covered it with dirt. Mine were silver-soldered to copper strap, and the brazing still looks as good to this day as it did after I first completed the job.

[ke7trp]

Rob thanks for the long reply!    This is exactly why I wanted the vertical. Over 1000 miles. My antenna now works great. But I wish I had a lower angle for farther DX. 

My concerns are, how to load this thing and make it useable on several bands and is the low angle radiation going to tear up the neighbors.

Derb, The base is about the size of a large Pizza.  16 to 18 inches.  Its about 2 ft high, solid Ceramic. It has a top plate and a bottom plate to mount it to the deck of a ship.  I thought it was about 150 lbs but my brother reminded me that its more like 300.  He said two of us can barely move this thing.  Its 68ft long so it looks like it was made for low bands.  I would have no probablem running a 10,000 watt key down into it.  So I wont have to worry about power handling. 


C

[N3DRB The Derb]

that antenna with a good radial system would probably make you a strapper back into the east, Clark. the T368 into that vertical and you would rule over 1500 miles out. Closer than 1000 miles out high dipole would probably out do it.

Don is absolutely correct on the radials/baseplate.... braze the system in place using copper strap and a decent copper/silver brazing rod. standard rosin core solder is NG, it wont stand up.

I'd go to a metals place and get a thick copper plate and some 2" to 4" copper strap. dont worry about holes, just set up a thick ring of strap around
your plate and braze yer radials in place. the nuts and bolts thing looks good but it quickly turns to junk like don said.

look for names like sta-silv 5, 15  or flos flo 7. Company called Lucas Milhaupt Inc. makes excellent copper and silver brazing alloys.

I am going to use their self fluxing copper rods called flos flo 7 as it is self fluxing due to phosporus content on my new ground system.

[ke7trp]

Sounds good guys.

Any advice on how to load this up for multiband use? 

Any thoughts on how the neighbors are going to act with a vert vs my Zep?

C

[flintstone mop]

check how this guy did his.

http://www.k9ct.us/Photos/Vertical/index.htm

pretty tidy.  But he needs a lot more copper than that 1 little bare 10 gauge round wire he has running ---more like 4 2" straps minimum.

Why did he mount his vertical so close to the tower with the Yagi on top??

If the antenna will be 100 feet from the neighbors, it should not be too bad. The problem might be the RF not able to find a good ground return. The radials will be important, not grounding. You might consider a feedline isolation balun to prevent RF coming back to the shack.

fred

[KX5JT]

Sounds good guys.

Any advice on how to load this up for multiband use? 

Any thoughts on how the neighbors are going to act with a vert vs my Zep?

C

Clarke, Check out Zero-Five and DX-Engineering for examples of the multiband verticals.  It seems that most are going to require an UN-UN (not a Balun) at the antenna feedpoint and a heavy duty tuner in the shack.  This seems to be the most practical setup for non-resonant verticals to become multi-banded.  Of course a doghouse with tuning right there at the feedpoint would be more efficient but not nearly as convenient. 

Good luck!  That vertical ought to help you reach my station a bit better!

John KX5JT

[Steve - WB3HUZ]

Another option is to put the tuner right at the base and remotely tune it.

If it's 60 some feet tall, you might not need any tuner on 80 meters. The feedpoint impedance would be high on 40 meters so parallel tank with a tapped inductor would work well for tuning. If you have a good horizontal antenna up for the higher bands, the vertical probably won't be any better for DX. So for 80 and 40, a switch to cut the tuner in and out might be all that is needed.

[K5UJ]

he won't need a choke on the feedline at the feedpoint if he uses enough radials.  chokes are for guys who use a few elevated radials (which is fine if they are high enough) and everyone else who only put down 5 or 10 radials on the ground and think that's good enough (it isn't).  Then the return current divided amongst the rads and the coax is high on each one but if you use 60 or more the current divides down enough so it is not a prob. on the coax shield.    Ask urself if a bc station uses a hellified choke out at the tower for 50 KW.  I used to wonder why hams do all kinds of stuff BC stations don't.  well they don't because they don't need to with 120 radials (also the feed is usually buried under the radial plain).  I started out with a gigantic coax choke at the feedpoint.  it was 100 feet of RG213 wound on a small plastic garbage can.  I calculated the Xl was over 1500 Ohms on 160.   But, it also made the feed another 100 feet long.  One day I bypassed it.  never noticed any difference but by then I had 100 radials down. 

I agree that brazing copper is the way to go but I use the drilled hambone radial ring and have no problems for the past several years.  It may be the way I did it.  First mine is a few inches above grade.  It's all stainless steel hardware--nuts bolts lock washers star washers and the radial ring is s.s.   If there is a prob. it is that s.s. has lousy conductivity compared to copper.  But I hope the s.s. plate is massive enough so it does okay for a few inches of conductance.  It and the feedline are both bonded to a copper ground rod.  I also don't jack around with those stupid little crimp lugs.  I stripped the wire, no. 14 and wrapped it on each bolt two to a bolt and cranked it down tight with two socket wrenches.  the bolt and nut are held with a lock washer and there is a star washer between the wire and and plate.   If I knew then what I know now, I would just use some of my 6 inch wide copper strap and braise with mapp gas.  I may do that anyway if I can ever get around to it.

RFI with neighbors:  if they can deal with the visual you should be okay.   You actually probably give  more RFI with horiz. antennas for they couple with phone lines and stuff like that better than vertical.  that has been my experience here.  my verticals are no more than 50 feet from neighbors; one is only about 30 feet away.   

You may need a tuner, even on 75/80 if the near field has metal things in it.  Other antennas, wires, support structures, buildings with metal siding, stucco with wire mesh in the walls...anything big and metallic will reradiate and give you a feedpoint Z that will have a resistance and potentially a wild reactance.  At "resonance" your feedpoint Z may be something like 25 ohms +-J20 or something (the Resistance will go up with more radials) and if your feedline run is say, 50 to 100 feet this will get transposed in the shack to something that, depending on the freq., will be either not too bad or bizarre needing a lot of capacitance....can't say exactly; don't know enough.  The best thing is to put it up, put down as many radials as you can and sweep the antenna with an swr analyzer and make a table from 3500kc  to 4 mhz writing down the swr, R and X (L or C) every 20 khz or so.  You'll have this long list of values but then if you can do modeling with TLW (transmission line for windows, a modeling program that comes with the ARRL antenna book) you can get an idea of what kind of tuner you need if you need one at all.  I prefer L networks for unbalanced feeds/antennas. 

All this isn't that big a deal -- don't let the proximity of metal structures prevent you from trying it.  I have a house and garage with alum siding and all kinds of other antennas and support poles all over the place.  They all react with each other but you learn how to tune stuff out and there's always a way to get a match of 50 j0 to ur transmitter, then just operate and the wavelength is so long relative to the size of the surrounding structures (assuming you are not next to a 6 story steel beam building) you'll get out FB.

rob

[ke7trp]

My original idea was to measure this thing, (my brother says its 68ft) and then figure out what I need.  I have two huge BC coils here. One is like 2 ft and the other is 3 ft long. About 8 inches in diam.  I thought about trying to use them, if I actualy needed them. 

I just bet that if I coax fed it, I could trim the length to get it matched on 75 in the ghetto. But I really want to use it multiband. I see that lots of hams are using verticals with a matching box at the base. In fact, I talked to a guy today with an S9 vertical using that box on 40 meters. He has a big signal to me 300 miles away.

What I want to know about is even if you use such a matching box (unun). You might have huge losses in the feedline correct?  I have some half inch heliax I can use. 

As for tuners, I have another KW matchbox that I can use and I also have a palstar roller inductor tuner and a big heathkit unit in the other room. 

How about using the 939 that the T3 is supposed to use?  Will I not still have huge losses in the coax run?

Clark

[K5UJ]

I am not familiar with the 939 but it doesn't matter; I think your question has to do with tuning in the shack.  Loss depends on feed length and how wild the vswr is at the feedpoint.  If it is 4:1 but you have a 35 foot long run on 75 m. the additional loss isn't very much.  If it is 10:1 or you have a 300 foot run then you may notice a difference in tuning at the antenna.  (correction: will notice a difference if it is 10:1 or more).

I don't know what a S9 vertical is.  1/2 inch heliax is good.  Yes you will have loss even if the load is 50 ohms; just less loss. 

here's why hams tune at the load (assuming they know what they are doing):  I^2R loss minimal for forward power only; no reflected; length of the vertical becomes somewhat unimportant. 

You know how guys are always trimming their coax fed dipoles for "resonance" (i.e. a low vswr where they are measuring it usually in the shack which they think is resonance).  They do that because they can't put a tuner up at the feedpoint because it would be costly and difficult to do.  But with ground mounted base fed verticals, all that doesn't matter.  It is pretty easy to put a tuner at the feedpoint, all you have to do is make it weatherproof and remote tune it if you want to be fancy.   So, there is no longer any need to prune the antenna (except for one technical matter I'll get to shortly).  Many broadcast stations work with towers that are all sorts of lengths that have nothing to do with their frequency of operation.  Some use 60 degree towers; others 150 degrees (90 deg. = 1/4 w; 180 deg. = 1/2 w) or 190 degrees.  Only hams are preoccupied with length, resonance, low vswr because they think a properly or correctly constructed antenna has to be 90 degrees based on that formula 234/MHz and have this self-producing vswr null in the middle of the band at which point they announce it is resonant.  All this goes out the window if you tune at the feedpoint.   What does matter with regard to length is efficiency, so length does matter in a general way but not in the critical way that hams think when they add or subtract a few feet.   IOW if you operate with a 45 degree vertical you can tune it at the feedpoint and the coax and rig are both happy because they think they have this nice load but your field strength (i.e. efficiency) will suck compared to what it would be with a 90 degree vertical.   this is why physically small verticals with big coils at the base don't work all that well.   Top loading a short vertical with a capacitance hat works much better from an efficiency standpoint, the hat makes the antenna seem electrically long (I don't know why) but doesn't loose power the way a loading coil at the base does.   And 180 or 190 degree antennas generate an even stronger field than a 90 degree vertical, but that is partly due to a lower takeoff angle.  Beyond 190 degrees you start getting high angle lobes and if you get real long everything starts going straight up which is why the famous all-band 43 foot verticals don't work all that well on the high bands and don't work all that well on 160 (really inefficient on that band because they are around 35 or 40 degrees and have no top loading). 

I would not use a matchbox; i'd go with an unbalanced tuner like a simple L network; save the MB for balanced line.  match box and unun are two different things; 1:1 unun is just a choke; other ratios do Z transformation so are transmatches in a sense but  are not adjustable.  I don't like them myself;  for one thing, my experience has been that ununs and baluns don't get along well with AM.  There can be issues, like heating and saturation.  you'll be happily buzzarding along and all of a sudden you'll see your output tank arc, vswr go sky high and smell something smoked and there's your ferrite doodad.

Rob     

[KD6VXI]

Clark,

Couple things:

First, if you use the antenna on the lower bands, the loss, even unmatched, isn't going to be as bad as say 10 or 6 meters.

That being said, any mismatch on coax = loss.  LOTS more loss than compared to parallel feeders.

You could tune it with coaxial stubs at or near the feedpoint, if you wanted to multiband it.  Lump a network at the end of a hardline stub to tune the reactance out, and have it at the end of a halfwave length of hardline.  It will appear as an open at 2Freq.

You can use coaxial cable for this as well, but I know you have a plethora of hardline, and it really lends itself to use in this regard, as it has little loss.

This is a spot where that crappy radio shack rg8x WON'T cut it!

--Shane

[ke7trp]

Rob, thanks for the right up.  Maybe this will work for 75 then, Coax fed, I can tune it by lenth and maybe match with a tuner in the shack to get more bandwidth.

Its going to really have a ton of loss on 40. 

Maybe I could load it to 160 with the big BC coil.  But then I would be 160 only.  I dont spend much time on 160 now.

I thought it would be neat to have to get out to the east coast AMers.   maybe I am better off with a High tower?

What got me thinking about this was the T368 and the 939 tuning unit. Which is a robust tuner with big ceramic insulators and vac caps.  They loaded the T368 into an 18ft whip on all bands and the spec was 100 miles flat land.  I thought maybe I used that tuner with this big huge Vert, I would get decent performance and have some fun. I guess not.

C

[N3DRB The Derb]

if its a 68 ft vertical, it's a 1/4 wave vertical. you dont need any tuning network at all. feed it directly with an decent KW rated coax, and for starters  try 50 radials each 65 ft long. your ground return makes up your "missing 1/4 wave".

i f your ground losses are low you'll probably wind up with about a 25~30 ohm match AT THE FEEDPOINT . This is a good thing. verticals with 50 ohm feeds are dummy loads, half your power is heating up the ground around the base of the antenna.

multiband, I would top load it for 160 using 2 wires, 40 you gonna have to use a tuner. build a "dawghouse" at the base like KYV did for his tower.

put te 939 out there.

[ke7trp]

I wont know until I measure it.  Its at least 60 ft. Maybe 70.  Its laying in a pile right now.  Maybe we can tilt the thing up and get some measurements with the MFJ and some coax to at least see where I will be at.

C

[KD6VXI]

Clark,

I know your soil....  And I use that term VERY loosely.

I'd say LOTS of radials, as long as possible (center the antenna in the back and pray it doesn't attract the tweeker scrappers ).....  And you might need a choke as well.

He lives in umm.....  Sandy rock?  Arizona desert...

It was comparable to my location in Tehachapi...  And any vertical I had ground mounted was in the vicinity of 70+ ohms...  IIRC, 36 or 32 is 'perfect', or so they say.



--Shane

[WD8BIL]

In the end....... will it work?
There's only one way ta find out.

[Steve - WB3HUZ]

If it's close to 60 feet, as Derb noted, you probably won't need any tuner for 75 meters. Forty is much more tricky since now the vertical will be about one-half wavelength and the feedpoint impedance will be very high. A tuner will be required for that band. Also, half-wave verticals are more lossy than quarter wave verticals, so you may not see lesser performance on 40 as comapared to 75 meters.

Dino, WA1KNX had a killer signal from Tucson over the last 4-6 winters using verticals. It's worth a shot. And if you have a coax switch in the shack, you can A/B it with your dipole and perform endless antenna comparisons like The Tron.   

I wont know until I measure it.  Its at least 60 ft. Maybe 70.  Its laying in a pile right now.  Maybe we can tilt the thing up and get some measurements with the MFJ and some coax to at least see where I will be at.

C

[WA1GFZ]

HUZ,
Remember the guy with the new antenna at Deerfield...Well he just happens to work second shift at a Lab where I was just doing a test. I can get contact information if anybody wants to try a super new design.
He gave my tech quite a line.

[Steve - WB3HUZ]

Yes, the antenna in a box. I didn't see them at NearFest that last few times. I wonder why?

[KM1H]

At 60' it will only provide low angle on 80/160M, the higher bands will be cloud warmers. I tried operating a pair of 80M verticals as 1/2 waves on 40M years ago and even with 1200W it was hard to bust DX pileups on CW or even get good reports from the average European.  A vertically polarized delta loop hung from a tree branch was better. At an earlier QTH in the 60's a 40M Bobtail curtain kicked butt.

Carl