The AM Forum

Well, it's taken me all summer to get this far, but so far the 190' tower has been stripped, three 40M Yagis have been built and two have been raised.   I still have to raise the third one and connect them all up.  Had many other non-ham projects this summer, so progress was slow.


These are homebrew, 250 pound, full size, 40M Yagis built from scrap yard aluminum. The tower is a 190' self supporter, rescued from WATR in Waterbury, CT.  The reflector elements are 70' long - using NO coils, stubs or traps.

The three Yagis are stacked at 190', 125' and 62'. (Spaced every ~63' apart)  They are fed in-phase and will produce a single low take-off lobe at about 13 degrees on the horizon.  The reason for the stacking is to fatten up and compress the low vertical lobe and remove any high angle.

So far it's been a solo effort. I've built and raised the antennas with no outside help. Just raised and bolted on the second one today. The last one at 62' will be a piece of cake... ;D  It's amazing what can be done with a lot of planning.  I try to minimize the number of climbs. It's something like a spacewalk where you don't want to forget anything.

I figure they will be operating by the middle of September.

BTW, the tower sections are 20' each. If you look closely at one of the pictures, you can see the bracket where the last Yagi will be bolted on. (at 62') The Yagi on the ground is #3, and will be ready to raise soon.

Wish me luck!

Tom, K1JJ

More shots:

WOW !!  Things of beauty,  Tom.

Assume that for now at least,  these antennas will not rotate (?)

The first time I worked you,  Tom,  is was on 10 Meter AM,  and there,  too,  you were running 2/ 2/ 2/ stack,  but I forget what rig you were running.  This was in 2000 or 2001.

73  GOOD LUCK,  will be listening.     VIc

Hi Vic!

Yes, I agree – they are a thang of beauty.  I sometimes think I build these things just to put them up and admire…  no kidding.  It’s fun just walking around and checking them out.

Anyway… yes, the 2x2x2 is fixed on Europe for now. Europe is extremely hot now on 40M and the array has been optimized and modeled for the trip. The horizontal coverage is fairly broad, being 2el Yagis, so they will cover from Sweden to N. Africa and beyond.   I could always add ring rotators later, but I have another solution…

I think the 2x2x2 array would be much too low angle for USA. I’ve found for USA west, the angle is much higher on 40M, so I put up a three element wire Yagi at 70’ fixed west.  I did the same thing for S. America.  Also have a wire dipole at 45’ for the locals. So, with a coax switch I can switch any of the antennas to cover the major directions, in addition to a set of beverages in dual diversity receive. Should be loaded for bear this fall…  8)   

I really like the 2x2x2 stack concept.  I plan to experiment with a 2x2x2 for 20M that is mounted as three elements – two driven els with a common reflector to give instant 180 degree directional changes. Add a second system and you’d have all four directions covered with no rotators.   Same thing for 10M.  I presently have long-boom stacked Yagis for 10 and 20M and wud have to recycle the aluminum. Maybe next year.

Thanks for looking and sharing the excitement, OM.

73,

T

Come on Tom. You need to think BIG! Only 250 pounds each? Sup wit dat?

(As previously stated, they are things of beauty! Nicely done! Be careful and good luck!)

           
        "It's amazing what can be done with a lot of planning"


Tom,

Your arrays and "planning" have long been iconic to piss-weakers like me (with single wires up near 100 ft).. It's like being in a locker room with a guy with REALLY big hands..

 I would love to read a journal or a JJ manual covering that planning and how you were able to get those big boys up alone, etc..

Anyway, congrats on the fantastic RF hammer pointing out east.. !!

73, Jeff

Hi Tom,

What a stick you have there and it looks nicely loaded.  Of course full sized elements are the way to go whenever possible.  You can't beat a commercial/professional grade tower with those 20' sections and flanges on the ends and thick wall or solid legs.  Surely you didn't stack the steel yourself though or do you have one heck of a gin pole?  Nice thing about those free standing 20 foot section towers is they can often be assembled on the ground and plunked down on a base with a crane.  What's the feedline out to the tower going to be?  I'm guessing 7/8" heliax?  Well if there's any AM activity on 40 in Eu you should be able to root it out with that.  On this end checked the currents on the feedline to the low band dipole and they're equal so the other near field antennas aren't unbalancing it surprisingly--had one of those great long QSOs last night on 3630 where the carriers were strong enough to blank out all the QRN--hope you get back on the air in a few weeks with no hitches.

Rob

Ah, you got the second one up. FB OM!

Great shots too. This is more momentous than a shuttle launch!

The Euros are gonna lose their minds.  ;D

Tom,

Good job and great pix.

I need to get the antennas up here in Wyoming and finish putting the shack together, but I spent my last 16 days off, fishing and riding my Triumph Bonneville.

Thanks for the inspiration, maybe I'll get it done in September.

73

Marty

Tom Vu running 3 duces on 40 ;D

Tom, you will have to reveal the magic pills you take to give this type of energy. UN believable.

Prolly 20 dB forward gain and 50dB front to back

Be careful up there!!!! It sounds like you do solo work......not goodness

Fred

Shame... having to endure such radio hardships...

...maybe one day I too and others amongst us will have such onerous problems as well...     ;D

               _-_-bear

As a famous Big Gun once said, "It's good to be king."

TOM VU
Give up on being Hammy Hambone and become a short wave broadcaster. Three phase power and 250kw should do it. You can be da king of da air waves.

Phred

That gives me a woody Tom ;D You will have to bring lots of photos to Nearfest.

I would kill for a tower like that with no guy wires. It was a major multiperson affair to get a pair of 4 el 40M KLM's on my 180' Rohn 45 stick. And every time the top one broke it was a repeat and break they did due to the way the wind hits this hill above about 120'. Finally sold the good lower one and turned the other into a 2/2 sorta Cushcraft clones. Those are down now also as Im doing a reconfig of the commercial stuff that helps pay bills as well as constructing an obscene 6M array.

Id figure real world gain of 8.5 dBd for your stack and 15 dB F/R. The gain would seem like more in a stack due to the lobe compression and F/R can be greater or less at times. When the 4/4/4/4 for 20M was up I could feed several combinations that were real handy to follow propagation angle. All were individually rotatable which was another big plus. That was a key to winning DX contests.

Are you going to do switching such as low/middle, top/middle, and all 3?

Carl
KM1H

Thanks for the comments, guys!  It gives me more motivation to finish this project.  Today I finshed assembling the #3 Yagi and it's ready to raise up.  Still, so much to do around here.


Jeff/NBC :  Yes, there's hints and kinks for tower work that make it easier and safer. The key to going solo is using a tram line for a guyed tower or a simple pulley and rope for a self supporter - and using a vehicle to both pull up the antenna and at the same time holding tag lines to keep it going straight. No reason to need a big ground crew, etc. Once up, just climb up and bolt it on. Run the coax cable on your way down. Hang all your heavy tools, come-along, ropes, etc on the boom and pull it up wid the antenna. Less weight to climb with.  Use a safety cable line to climb with in case of a fall.  Bring up a water bottle to drink - and drain your log downwind.  Some complex climbs can last up to 4-5 hours.  Try to do as much as possible on each climb. Make them count, cuz there's only so much physical energy available.

Rob/UJ:   These are a pair of 190'ers that I put up about 11 years ago. They are solid steel, not pipe. The bottom 20' section weighs about 1500 pounds. I hired a crane to put it up. It wuda been way beyond my own capacity to do it with a gin pole, though some OT's still do it that way...   The feedline is 3/4" hardline with internal disk wafers spaced every 3" for very low loss dielectric properties. There is about 550' from the shack to the tower for the 40M array. That's about 0.6db loss on 40M.  No big deal.   Looks like your new antennas are working out beautifully - congrats.

Steve/HUZ:  Yep, it's as EZ as 1-2-3.  Or the Brooklyn ham might call it a "do over do over do."    The Euros are gonna lose their minds.... HA! I like that.  [I don't know if you guys realize that the HUZman holds court on 40M into Europe a few nights a week. The pile ups are legendary. That pair of switchable delta loops he uses is something that can be duplicated by the average ham with 60'-70' trees..]


Marty, FB on your Bonneville. I once rode a Triumph TR-6 bike to Calif and back. What a ride.

Carl:  What do you have planned for 6M?  I wonder if it's one of those stacked 2el Yagi arrays or is it a few big boom Yagis? 
The 2x2x2 on 40M has a sorta "curtain effect" so the model shows a f-b that is at least as good as a 3el Yagi. 25-30db is realistic. 2el Yagis stacked are a really good system.   I don't plan to switch them low/middle/top. I had up 2x2 40M Yagis before and found that 95% of the time the two in-phase was best. I also found this with the 10M 2x2x2 using a Stackmatch. I made it simple and just want to work the weak Euros at low angle. No corntesting here. Though I can imagine the stackmatch to be FB for corntesting as you have found.
Interesting on your 40M Yagi wind problems. Yeah, they sure can get beaten up with those long elements.

**  I took some closeup  pics of the third Yagi for construction tips - to be posted next:

Later -

T
 

Here's some close ups of the boom to mast plates, feeding system and boom.  This is the third identical Yagi ready to go up.

Notice I use a 4" ABS pipe with 8 turns of RG-213 wound on it and six ferrites as the balun chokes.  The driven element uses a solid 2.5" fiberglass rod as the center insulator to split the dipole halves. 

I use up to six u-bolts through the 1/2"! thick element to boom plate to keep the element from spinning on the boom. Wind, ice and other stresses can spin them. I also use two pins (1/2" bolts) thru the plate and boom.  I've once had a 40M Yagi spin an element in wintertime - never again.

All stainless steel u-bolts used throughout. Most of the ones you see have been recycled over the last 10 years and still look new. I sometimes cheap out on the bolts and buy regular plated steel, but always regret it when recycling. They are always rusted toast after a few years, though still strong. Heavily dipped galvanized bolts are not bad, however.

Notice the four bolts holding the boom together. I use 3.5" diameter aluminum pipe with 1/8" wall  to 3" boom.  The boom is only 17.5' long and is also trussed with a 1/4" steel overhead cable. It will be bulletproof for ice loads. The elements have no trussing, but are good for 1/2" ice at 130 mph according to YagiStress. 

I use TWO #10 teflon wires to connect the coax to each half dipole - with two copper lugs on each half element for redundancy. They are taped and  sealed with RTV and use their own bolts.  Connections are a problem with the WX, OM and I never use coax connectors out there. Everything is hardwired.

To match the 16 ohms of the combined three parallel 50 ohm Yagis, I built a coaxial 1/12 wave balun consisting of three 7.5' lengths of RG-213 in parallel - in series with one 7.5' RG-213. The single balun coax goes to the three Yagi feeders and the triple balun coax goes to the 50 ohm hardline up at the 125' level on the tower.  This should provide a reasonably low swr.

The resulting vertical takeoff lobe looks like a cigar aimed at the horizon, caw mawn. Coupled with a good f-b and high angle suppression, the s/n ratio shud be very good into Europe.

73,

T

Construction Pics - continued:

Happy Birthday Yaz!  Six years old on August 29th.

For a present, I'm taking him out sailing with a gourmet doggie lunch at his favorite spot... ;D

Tom, there will be 4 x 5el rotating on the mast above the 40. I dont want the wind hassle of long booms and massive H frames. This is a one man show. I have a HB long boom 8el at 60' now on the little tower and it is very effective. I'll leave it there as a benchmark.

On the side of the tower will be a 32 el collinear taking upn a lot of vertical real estate. They are a pair of 16 el Cushcrafts that I rebuilt with newly machined insulators and had one up fixed on EU for several years. Only 3 were custom built, mine came from Sam Harris, W1FZJ, and Wayne Green.

The footprint of this hill is rather small and falls off fairly evenly for 360* and as much as 450'. N1BV (ARRL antenna Book, etc) modeled it and K6STI included it in his Terrain Analyzer (TA) program.This seems to have the wind come in low and then get directed up and compressed by the slope and trees. The effect is huge when I cross the threshold level, even with a dead calm on the ground.

Carl
KM1H

Wow!!!  Are those bad boys visible from Route 2? 

Sure looks solid Tom. Did you get that fiberglass rod idea from Chuck or vice versa?  He used that material when the 3 el 80 got rebuilt before I bought it.

Finally decided it was too much for this location so it and the 200' of BCB tower I had (similar to Rohn 65) went to 9 land.

I used similar plates and mounting on the stack of 4 el 20 which were on 40' x 3" booms. No amount or wind or ice ever fazed them. I used a radical taper schedule going from 1 1/4 to 1/2" and it rode like a bird in the wind and the ice just slid off. Probably nothing that Leeson would agree with but I never bothered buying it either ;D The first pair were built long before he wrote it so I was confident. Almost 25 years of surviving for them but the high ones were tough on rotators at this QTH as was the 40M on the mast. The 20's are now a pair of 3 el on 20' booms which even a Ham M series can handle on the sidearms.

At the prior QTH which was in a bowl surrounded by hills (Im on top of the biggest one now) I had just a single 4 el 40M KLM at 140' and the winds were generally calm except when Gloria came thru and everything survived.

The things we go thru to kick ass with a better signal.  ;D

Carl
KM1H

STRAPPING!

Yaz is 6 already. Sheesh. I am getting old. Seem like just a few years ago that I visited and you had just got him as a pup.

Carl,

I've used fiberglass centers for a long time now. The 10-20M log periodic used them for every element. It sure is a better technique than those Teflon inserts that KLM used for Chuck's 3el 75M Yagi.

I remember almost buying that Yagi from you back in the early 90's. I didn't know you had a big tower to go wid it too. I don't expect to ever put up another 75M rotary Yagi again. I like the wire delta loops for longevity. Seems no one can keep up a rotary for long on 75M.  There's a ham up in NH that has one at 190'?   He has the XX crew work on it and I think it's been up and down the tower at least three times now. Haven't heard him on in a coupla years with it. It was a rotating tower.  40M rotary Yagis are the limit for me.

FB on the 6M 16el Cushcrafts. How long were the booms and how heavy were they?    Two years ago I built up a 6M Yagi with a 110' boom. It was absolutely huge. I wanted to turn it wid my prop pitch. But after building it I realized it was just too damn big for one guy to handle, so I recycled it into other antennas.  Soylent Green antennas.

That's amazing how the wind hits a mechanical resonace and amplifies itself at your QTH, so to speak. Makes sense, just like water can be made to increase pressure and speed by being forced through a smaller opening.

Well, tomorrow I raise the last 40M Yagi to complete the raising. It’s all set up and ready to go in the morning. Then it's time to connect them all up and do some testing.  Oughta be fun holding court into EU.

BTW, also got the 75M delta loops working FB. They are switchable NE/SW using relays and 142 degree coax stubs on each element. The reflector connects to an 11uh coil while the other is directly fed. Then the relays switch it over to reverse directions. Huz uses a similar system on 40M as well as Matt/XX for his 75M deltas.  The f-b is about 25db.


Chris/AJ1G:  No they can't be seen from Rt2, but can be seen from the next few set of hills. Rt2 is in a valley and too close to the QTH.

Steve:  Yeah, Yaz is in his prime "good guy" phase. I've always thought it takes about 5 years to train a dog until he is about perfect. Then the next 8 years or so is bliss. They know all your habits and you theirs. They aim to please and cause little trouble.  Yep, Yaz is a good guy now and deserves a big party this weekend. Bring Shasha and let’s dog party like it’s 1999, caw mawn.

Later -

T

Yeah, no more crazy antennas for me Tom.

The 6M CC's are on 4' booms, this is a collinear just like the old 2M ones of the 60's. Each bay is a full wave reflector and a full wave DE insulated and fed in the middle. That equals 4 el. Each bay is 1/2 wave spaced. I will setup to select each 16 el group or all 32. It has a wide elevation lobe as well as a huge azimuth lobe. Great for aurora and meteors plus contesting. I'll probably have the 20 el yagi array switched in also or maybe use one amp for the collinears and another for the yagis....at the same time. The gain should be impressive ;D

Carl
KM1H

That's a real nice antenna there, I'm a little jealous.

Well now that I've recovered from being in awe, thanks for sharing the photos and construction details Tom; the chokes and feedpoint detail sure wwew interesting.  I'd say I picked the right guy from whom to follow antenna advice.  I'll enjoy reading a description of how they played into Europe after you've been operating for a night or two.   I was a bit surprised to read that you are using the gas dielectric heliax.  Are you pressurizing it with nitrogen or pumping in dehumidified air?  I sure hope ur wx continues--looks pretty good in the photos.

73
Rob  K5UJ  

There's a reason we call him Master Vu!   ;)

[

OK on the collinear 6M beams, Carl.  Yes, I remember them now. I almost constructed the same thing until Chuck told me of some tests run by a guy who first tried 2el  ½ wave Yagis and then tried the full wave els. He felt that on 6M, supporting the els at their high impedance points was lossy thru the insulators and canceled out the extra ~2.5db of gain.

I took this advice and made an array using  ½ wave Yagi eles supported at their center low impedance points instead. I wonder what your opinion is of this? 

Here’s a pic of the 6M array. It faced NE or SW, switchable via coax.  It started at 190’ and went down to about 55’.

BTW, I compared it against my 7el  6M Yagi at 190’ and saw little difference into the W3/W4 area. I know they were working and phased correctly.  I wasn’t impressed enuff, so might try some form of fixed array using  two or three  Yagis with slightly longer booms in various directions. As you can tell, I hate rotators, but might make an exception on 6M and use my prop pitch for one big MoFo. The jury is still out. Even though 6M is a gay band, I still like the magical action there… ;D


Check out the LONG boom triple 6M stack too. All homebrew.


Rob/UJ:  The hardline is just regular stuff - no gas. It uses disks every 3" to support the center conductor.

T

Wow Carl,
you bought Chuck's ant. I saw it on the ground just after he rebuilt it.
 What a beast to cover such a small frequency range.

Nuthin' like the sight of the sunlight reflecting off of aluminum in the morning sky!

Great antennas Tom!  I once had a 60' boom behemoth up for 20 and 10, along with 4 elements w i d e spaced for 15 all on my 80' chunk of microwave tower.  Used 4" mast and turned it with a large prop pitch motor.  Unfortunately, a tornado passed over and high winds aloft wound my 60' boom around the tower.  Never was able to replace those antennas...just too much of a job to put them up and maintain them.  Sure worked good though!  I used to look for pile-ups to exercize my antenners...didn't always get thru right away, or first in line, but it usually didn't take long to be heard.  I always believed in the words of wisdom:  "Don't worry too much about the radios, spend the money in the back yard!"   ;D

73,  Jack, W9GT

K1JJ PRESENTS MR RADIO STARRING TOM VU   :o AT THE MICROPHONE  ;D

Hi Jack,

Those 60' boom 10M and 20M Yagis must have been tremendous.  It’s not easy to get one of those antennas tuned correctly and erected, but what performance!  The long boom even lowers the take off angle to boot.

I believe in focusing efforts into a FEW antenna systems and having lots of fun working with optimized stuff.  Being all things to all bands is near to impossible hardware and time-wise.  For example, I’d rather spend the time building up a big array for Europe on 75M and be able to hear and work stations that most cannot – rather than  spending the time on generalized antennas like a large omni-directional vertical and radial system that’s designed to work everywhere.  I mean, if wanted to work everywhere with average results, I’d just make a cell phone call….     Hello, Pascal? You’re 59 again tonight on the telephone. Reply: “Stop calling me every night you idiot!”   ;D

I’ve decided to eliminate a few bands and directions here to have the room for all-out antennas on a few bands in certain directions. I took down my 160M antennas and also 15M Yagis. (and 6M Yagis for now)  I find 160M OB transmissions too much to handle – and the 160M DX into Eur is sparse on ssb. CW is fun, but quite lonely.  15M interacts terribly with 40M, so that was an easy one to eliminate.

But when I get on 75M or 40M I have three major directions with f-b and gain. 20M uses a pair of stacked 60’ boom Yagis that is presently on Eur but can be rotated anywhere else using the Armstrong method.  10M uses a triple stack of 5el Yagis. That’s it. I have lots of gaps in band coverage, but the ones I do have are like getting into a dragster and popping the clutch. It’s a blast to call CQ for Europe and be able to hold court with many stations calling. It’s usually the USA chasing the DX. I like to give them some fun for a change. 

I also like to give out very specific S-meter reports. Hams love to know how they stack up against others.  Telling everyone they’re “59” is a joke. I always watch the meter carefully and give out an exact S-meter report. This increases the pileup and gives the DX something to compare with.  Pausing to listen for mobiles and weak 10w UK foundations stations or weak Russians adds a flavor too. Picking out the weaker ones in a pileup is fun and gives everyone some action.  I just love working the Europeans and hearing their diversity. The Russians are crazy about radio and very enthusiastic.

One of the most effective stations and most skilled AMer/DXer is WB3HUZ. He’s put up a very well-tuned pair of 40M delta loops that kick ass. With his beverages and K9AY loops he can hear very well. I heard him on 75M the other night working a pileup in the static just using a dipole at 80’. He does better than some “big guns” on that band. Wait til he gets up his 75M phased dipole array.  His QTH’s lake, drop off and swamp in front of his antennas seems to help a lot.

Anyway, mixing up the AM activity with working DX keeps it fresh. It really pays to have two or three focused activities in radio to keep the interest up. Hanging on one freq night after night with the same group is a great way to get into trouble and burn out…

BTW, here’s a pic of my 20M Yagis at 50’ and 100’ on the other self supporter. It’s amazing what I hear outa Europe with these, even on a quiet band. Listening on lower reference dipoles is like unplugging the antenna sometimes. These Yagis feature insulated elements sitting 3” above the boom - using fiberglass for each. This makes it easier to use precise element lengths that are not affected by the boom currents, thus a better tuned Yagi..   These are 300 pound Yagis. One day Huz, INR, JN and I almost got a hernia carrying them into position. I always try to get a little work outa them when they stop by…

Been very busy for the last year on many projects, mostly non-ham related, so haven’t been on the air much. But want to get active again this late fall. I really enjoy working coast to coast on 75M AM and hope to catch you on then, OM.

73,
T

Tom, Chuck and I spent many hours here and at his place going over computer modeling of various 6M fixed arrays. I believe we both agreed that a stack of 3 el yagis as tall as possible was the most gain producer combined with a broad azimuth. We then retired to various Mexican restaurants, with a few like minded hams, that we were often escorted out of ;D

I went with the collinears since they were historic as well as free ;D  I was also concerned about the insulators at the HV points. The original ones looked like some form of ccompressed paper, all pulpy from decades on the ground. With new ones machined from black Delrin no heat can be felt after running 1200W for a few minutes into a single FW element and matching stub. Remember that there is virtually no current at those points, just lots of voltage and the dielectric strength of the Delrin proved more than sufficient. Split this up into either 4 or 8 driven elements and the effect is far less. I never noticed any detuning in the rain either and I always monitor screen current plus a dedicated in-line Bird.

My comparison antenna at that time was a 6/6 Hi Gain at about the same center height. Gain was about the same most of the time with one or the other having the edge at times into EU. On relatively local stuff, Lefty, K1TOL up in Central Maine, reported the collinear far superior and dubbed it the bedspring on his next visit. I designed the improved, and sold him, a 8el Wilson which proved to be a real kick ass antenna.

I next used YO to model the Cushcraft 6 el Boomer I picked up at Deerfield, or wherever it was that year, added 2 elements, and settled on a solid 13dBi  gain and a 35-40 dB F/R over the full 180*. YO reported gain was .1 dB from theory. My problem with the collinear was the 12-15 dB F/R and many noise sources to the back masking weak DX. With the 8el replacing the Hi Gains, the gain was again about the same but band noise was so quiet I sometimes thought something opened up in the feed.

As an aside I later took a serious look at the Hi-Gains, improved the pattern a lot and got rid of that almost a dummy load matching arrangement they used. The T Match is the only thing I will use.

With the collinears going to the other tower which is another 150' from the power lines and far above everything Im hoping the noise will be tolerable and that the blanker can handle. Im now pointing at the noise. With the noise being vertically polarized and at low angle Im keeping my fingers crossed.

Im lost without antennas that rotate, either electrically or mechanically. My interests are mostly DX and some contesting so 360* with lots of gain is imperative. Im not going as crazy as before and yagis will be limited to 2 per band on HF; no more 19 yagis on just the traditional HF bands 40-10M. Long path on 80/40 can vary from over central EU to the southern tip of Africa depending upon what the propagation gods deal out. On 80/75 a dual element inverted vee at 180' often blew thru the 4 sq and 2el yagi bunch. This is at 1200W. With the pair driven at right angles as mentioned elsewhere on here I had 360* directivity with a mix of V & H polarization and the Beverages indicated the path in use. Working the same EU or JA night after night bores the hell out of me and I'll often ignore a band for weeks at a time unless something really good pops up like the time I worked 3 Zone 23's on 80/75 the same evening to complete the 1st W1 5BWAZ once the QSL's arrived.

Happiness is pushing myself and the equipment to the edge at times. Ive also done substantial DXing with QRP, even on 160. But Chuck's 3 el 75 was a bit too much. If I had put it up it would have been with the 80/75 switching mod.

Carl
KM1H

JJ, thanks for posting all this inspirational material on how big gun's do it, caw mawn. Very impressive.

Carl,
Very interesting on the various antennas you've tried. I always find others' personal antenna experiences interesting.  I've also experienced a fair amount of noise with the 8-bay 6M Yagi stack. It sure had a lot of phasing coax to install. OK on the high quality insulators you used and the heat tests. Looks like it worked out FB in the end.

I did some modeling, thinking and axed a lot of questions of the gurus about the best sporadic E 6M antenna. Seems the best angle for that mode is about 20 degrees take-off. So I built up an 8-bay bunch of 3el Yagis on a double H-frame to be mounted about 20' off the ground. Killer medium-angle antenna. I never put it up, but thought that wuda been a great bunch of fun, to work E with an advantage. But most DXers are into F2 prop, so I'll look into something higher and longer boom I guess.

What is a pair of 75m inv vees driven at right angles to get a switchable 360 degree coverage?  What is the original config too?

Yeah, K1TOL is big up there wid that triple long boom 6M Yagi stack and the rotating tower. I saw his modeling work done by WX0B and it looked impressive. He hears pretty well as I found listening to him.


Well, it's almost September now and I guess we'll be winding down the antenna work pretty soon. I'm all antennaed out so after these 40M Yagis are finished, I might do a few minor antennas more and then call it quits for the season. I expect to make good use of the 75M deltas  NE/SW and the new 40M antennas this season.

John/Pro:  Glad you found the info valuable, OM. I find it helps me too to read what other guys are doing. HUZman's great success with his 40M delta loops spurred me on to do something with the Yagis.  I was satisfied with a 7el wire Yagi at 70' until I noticed he was starting to kick my ass on 40M into Europe. He's getting nervous now and looking for a 100' crankup tower to hang some rotaries.  ;D

T

I think everyone on 40 meters is worried! The rumors are out that a big tri-headed slapper will soon be descending on the band. The mud ducks are scurrying.

Tom, Ive explained that 75/80M antenna before, maybe even in Deerfield.

Any way its just 2 antennas at right angles and feeds tied together. One is cut for CW and the other for the SSB DX window. Gives a nice low VSWR on both. Both sections take power on either operating end since the VSWR means nothing to a radiator. No phasing line as with a turnstile which turns it into a cloud warmer. Since an inverted vee is horizontally polarized broadside with a vertical component endfire I wind up with both components in 4 lobes each. Over real ground thats close enough to 360* for me and it works as expected. I told Randy, K5ZD about it when I was still a YCCC member and he tried it and had similar results at a much lower height...90' I believe. It was subsequently written up in Scuttlebutt. Since 80/75 at greyline usually starts at a very high angle from West to East, and the reverse at sunrise, (the infamous one way skip) around 45* or so and then lengthens out having a wide elevation pattern works well. The other end of the path is the reverse and until the angles become somewhat similar or lots of power is used its like talking to yourself. I can track the changing band with the Beverage as I add or subtract sections, peaking around 2300-2400 local and slowly reversing towards EU sunrise.  Thats under normal conditions. All bets are off when the auroral zone pushes EU over Central Africa or we are inside it. Im more prone to that and the dividing line often seems to be the Mass Pike!

If I get time I want to put another pair 130' lower (at 50') and do an lower/upper/both switching. Should be interesting.

K1SG, Steve Gilbert, in Hopkington, MA has a 150' rotating tower with four 11 el for 6M and does rather well. All I want is the thrill of a long JA run on 6 with the new array next year. CW of course.

Keep us posted on the 40M system, thats probably the biggest in the USA??

Carl
KM1H

That antenna has big lobe at 90 degrees elevation, only 3 dB down from the main, low angle lobes at 23 degrees. I wonder what effect that has? I see nulls at the medium angles.

Which antenna?

Carl
KM1H

The inverted V at 180 feet.

How are you modeling it?

Carl

Top at 180 and ends at 130. Took a guess as the end height. Maybe your ends are higher/lower?

The ends wont affect that lobe. It sounds as if you are feeding it as a turnstile.

Try modeling a simple dipole horizontally and as an inverted vee.

I used MN and NEC Wires and it looked as expected.

Carl
KM1H

Just a single dipole at 150 feet. It has a big high angle lobe, null at medium angles and main lobes at the lower angles. This is exactly what I would expect for a horizontal antenna more than one-half wavelength above ground.

OK, that is as expected and I misread your prior thinking the high lobe dominated.

That high lobe is extremely useful when conditions appear to favor ducting phenonoma on long DX paths, primarily trans equatorial. Another side benefit is keeping locals at bay ::)

One extreme ducting example was the February 1990 3Y5X Bouvet DXpedition. I had just moved in here and had no antennas up. I quickly tossed up a 58' 25G with a 4el 10M on top and a full size 160M inverted vee about 5' lower with the ends about 4' above ground. Just a concrete base plate on the frozen ground and 2 levels of guys wrapped around pine trees in a somewhat 120* pattern. That tower is still there with no changes!
Id worked them earlier on 10 and when they showed on 160 the pileup was humoungous by the time I got on.
Figuring this would be an all nighter I sat down and sent my call the usual one time.....and he came right back!

Later on I worked the operator from his home and he asks what the heck I was running. He then told me I was at least 10dB above everyone including guys he knew were running 10dB more power. His comment went something like: "I was trying to get a complete call from anyone and tuning the full width of the pile and all of a sudden you exploded out of nowhere"

Carl
KM1H

As the old saw goes, "You can never have too many antennas."

Great story and a lesson to all. You don't necessarily need to have prodigious antennas to work DX, maybe even lots of it. Sure big antennas help but they aren't absolutely required. Sometimes timing and/or patience are just as important. Some guys have over 200 countries on 160 meters with nothing more than a 30 foot high dipole. Dive in, the water is fine.

I worked over 100 on a vee beam
Every Dog has his day