New 31 foot vertical homemade.

[PA5COR]

As you know I use (d) the Imax 2000 with radials for 10-17 meters on the roof.
Since 10/12/15 worked good but 17 already saw a decrease in efficiency I decided to make something nw.

It became the 31 foot vertical made partly of titanex alu tubing very strong and almost indestructible as used in my 77 foot inverted L.

Tested several 1:4 unun's piccie is of the test T200-2 core, with Teflon wire on it.

Last and chosen unun is the FT240 -43 core with 11 bifilar windings on it as 1:4 unun.

Bagged me testing on 15 meters Bear island with 5 watts...... not intended, but just happened.
Since this summer will see a complete redo and maintenance on the roof it will replace the Imax antenna for 40 - 10 it even has a good SWR on 6 and 4 meters, though the radiation pattern there might be a bit iffy....;)

Why 31 foot? I wanted to stay below the full 10 meter length, so it still gets a decent 10 meter pattern.
31 feet so the swr on 40 is now 1:2.5 measured with the MFJ 269 analyser at the balun can easily be tuned flat.
Made a 1:1 choke with a FT 240 - 43 core and RG 58 with 10 windings on that to keep the coax from getting RF on the outside.

Testing it here on the ground between the houses looking quite good, swr never higher as 1: 1.3 except 40 meters.
Could tune it even on 160, but will work as a leaky dummy load there with the 9.5 meters radiator.

So, why is everyone not building/making/testing homebrew antenna's here?
:mrgreen:137101371113712

[WØTKX]

Speaking for myself, it's because I'm not gainfully retired. Yet.

Besides, it's ski season. ;)

[NQ6U]

All but one of my antennas is home made. The one exception is a little 70cm ground plane that was given to me.

[PA5COR]

Old Imax 2000 top sections = given to me, as was the old Imax on the roof, cost = 0
Titanex tubing bought cheap from importer 20 feet total about 20 euro's. left over from the inverted L antenna.
Glassfiber camo stick 4 feet from the army, bought 3 at the hamfest for 6 euro, used one.
Is isolator and mounting section, 2,5 feet into the 31 fet section rest for in the clamps on the chimney.
FT240-43 core 9 euro, Teflon wire got 100 feet blue and 100 feet grey with silvered wire inside, 10 bucks from left overs of the building of an plane it is used in.
Add coffee, 3 hours work to fit together, lots of fun testing several unun's I had from other projects.
Inverted L homebrew, active loop homebrew, FD-4 spare homebrew.
Baluns unun's homemade.
Have fun ;)

[KG4CGC]

Nice project. I've been considering a vertical folded loop wire design. For SWLing mainly but it could work on 160/80 if I can get the feedpoint high enough.

[PA5COR]

Rebuild the antenna this afternoon, fine sunny weather 15 C and after working a few days the length of the antenna for 12/10 was too high, the lobes crept up too high ( over 5/8 on 10...)
So, took off the top, with the Imax 2000 sections, added Titanex alu piping up to 24 feet ( 7.35 meters) and retry.
Strangly the swr on 40 became better was 1:4 now 1:3 and above all mostly within 1:1.2 even 50 MHz...
Compared to the OCF and Imax 2000 on the roof it was decent, the Imax through being on the roof at 40 feet above ground did have om 15 12 and 10 a little higher signal, but barely.
Getting the 24 footer above the roof will clear the groundclutter and the choke balun added ( FT 240 - 43 core with Teflon coax)
A bunch of radials will do the rest.
The 1:4 unun still the same, Ft240 - 43 core with 11 bifilar Teflon wire windings.
Handled 400 watts carrier for 5 minutes without sweating.

So, all in all, 40/30/20/17/15/12/10/50 in one stick...

[PA5COR]

Final version, 25 feet radiator, Ft 240 - 43 Unun with 11 bifilar Teflon wires as 1:4 unun.
At the final install on the roof there will be added a Ft240 - 43 choke balun after that.
Stinger next to the radiator, 1 1/2 feet away from the radiator, starting from the ground connection 4 feet of alu tubing in the middle of the vertical section a 1,5 micro Henry coil, in my case 9 windings Teflon coated wire around a 20 mm plastic core that also holds the 2 vertical sections of the 10 meter stinger.
The stinger is directly connected to the ground section and radials, 5.5 feet total and coil from the ground connection 1.5 feet to the side then vertical next to the main radiator.
Use UV resistant plastic/Teflon spreaders to mount the stinger and keep the distance from the radiator.


That one will lower the lobe for 10 and 12 to dx levels.
Raised the antenna 5 feet from the ground, added 2 free hanging radials of 9 meter long also 5 feet above ground.

SWR from 40 meters up to 6 meters 1 on 1.1 except 20 meters 1 on 1.4 and 17 and 15 each 1 on 1.3

[W3WN]

I was serious, what I said in the other thread.

Get me some pictures, write me up a little article on how you designed and built it. I'll print it.

[PA5COR]

Some background.
The Imax does perform very well on 10/11/12/15.
17 already shows that the antenna can be tuned, it is not optimal.
Forget 20 and yes I run the Imax with radials up to 4 x 5 meters and original GPK package....
Chosing the main radiator element length I worked my way down from 31 feet to now 25 feet, went as low as 20 feet to see what the effects were in SWR, radiation resistance and efficiency.

Normally we pick a length that is maximum 5/8 on the highest frequency because otherwise the vertical will has it's lobes there pointing up in the sky if we use a longer length.
That would be 6.6 meters length, or around 22 feet.
With that length the 40 meter suffered quite in efficiency ( still well under 1/4 wave there) so not very effective low rr so high losses.

Picking the 25 feet proved to be a lot better, SWR now elevated 5 feet over ground and 2 radials free of the ground was very satisfactory.
Running 200 watts carrier in the antenna for 10 minutes on each band didn't heat up the 1:4 unun, ( Ft240 - 43 core)

All other bands were almost perfect, worst is 1:1.3....
The stinger raises the 10/12 meter current point and lowers the lobs to a dx portion instead as looking up too much, no other effects on the other bands, see the stinger as a stub.
after instaslling the stinger tune it to just over the 10 meter band 30.5 to 31 MHz for best effect.
Check with beacons on your reception signal for maximum effect.

On my chimney I see this as the longest vertical without guying I can reliably get away with ( concrete chimney) and force 12+ gales we have here sometimes.
That was the reason to pick the supply of Titanex tubing I have around here, from 1 3/4 inch up to the smallest tube on top of 20 millimeter, wall thickness 1/10th of an inch.

The FT240 - 43 was chosen to have a reasonably high Mu and therefore enough high value, 7 MHz is almost 20.000 Ohms, 29 MHz is 82.000 Ohms.
Mu is 850.
The same cores are used as wideband chokes here good for 1500 watts ( single core) and Teflon 5 mm coax around them.
I'll run my definitive tests with 800 watts later in the weekend when the stinger is at it's place permanently.
I tested T225 - 2 cores, and found them lacking, they handle high power but they need 2 x 19 bifilar windings to be a bit effective for 40 meters, and then the capacitance starts to throw things off the rocks.
Too long windings around the core form capacity and will put things off the scale.
Max length of wire on the cores is 10% of the highest frequency in use ( 10 meter max wire length 1 meter).
Put tape on the FT 240 - 43 cores they conduct,so isolate them and use Teflon wire to make the unun.

The stinger idea was from here: http://www.eham.net/articles/29052, found late yesterday evening and made today.
Read that article including the piccies diagrams lobes for each band etc.
I already decided to 25 feet max radiator length so the stinger was optional.

[w2amr]

Nice job Cor.

[PA5COR]

I'm a bad article writer, lacking those skills and my English isn't that good to be so eloquent as most writers.
Still testing around, tried a T225-2 Amidon core in 1:9 and 1:4 unun, but the FT 240 - 43 core with 11 bifilar windings with Teflon coated silvered wire still gives the best results.( used in the Airbus planes)
Everyone can use the data and piccies provided in this thread to make something about it if he/she feels it is worth producing it for a club.

This was my "hunt" for a better vertical as the Imax 2000 is, starting point was it had to work well from 20 up to 10 meters, no traps wich add losses and complexity, sturdy to withstand 130+ mile storms, be of reasonable length, manageable on the roof on a concrete chimney, but that also would work on the ground.
That would add 17 and 20 meters to the vertical working better as the Imax 2000.

The choice for an 1:4 unun to keep the swr on the coax feed line low was easy picking, I have been experimenting with that before in my quest for the 160 meter antenna a few years back I wrote about here.

Since I had a lot of titanex tubing around and the Imax top sections as spare I could change the lengths of the vertical from 21 to 31 feet and xperiment here on the ground ( 6 foot off the ground with raised radials) with the effect of the length and bandwith and effect of radiation pattern of the vertical.

I was not trying to re invent the wheel, there is a lot of stuff written about this on the net as I found out in the process, my initial database I referred to was Low band Dxing from ON4UN, the RSGB and ARRL antenna books, as well my own experiences in building verticals over the years.

In my first tests the 31 foot vertical was easy tunable from 40 -6 meters, with the FT 240 -43 core 70 MHz ( we have a band there here) and even 2 meter had usable dips, but the radiation pattern there will be quite weird to say the least.

Since I still have the working Imax 2000 with ground radials on the roof at 35 feet and top on 55 feet over the ground I can compare the vertical with the Imax 2000 with a flip of the Heathkit antenna switch.

The Imax is fed with 50 feet of a LMR400 comparable coax, low loss, the homebrew vertical is fed by 100 foot of RG58U that has about 3dB loss.
So, being higher up, free from the ground clutter and low loss coax compared to a ground mounted between the houses vertical with 3dB loss coax on it.....;)

The Imax is fed with a wideband circuit you can find on the net, andf has a 23 foot radiating element encased in the glass fiber parts.
The radiator of the imax is capacitive coupled and prone to static noise.
The 1:4 unun in the 25 foot new antennas connects the radiator to ground electrically, but I will add 180KOhm resistor of pressed carbon 5 watts over the radiator and ground connection as "just to be sure".
With 11 bifilar windings on the FT 240 - 43 core the 1:4 unun is working fine from 160 meter - 50 MHz as the MFJ 269 alayser showed in tests.
XL at 1.850 is 1.308 KOhm, on 80 already 2.545 KOhm, 7.1 MHz is 5.1 KOhm, 14 MHz is 9.686 KOhm, running up to 29 MHz 20.5 KOhm, 50 MHz is 35.5 KOhm.
These values need to be on the safe side 5 x as high as the feeder impedance, here 50 Ohm.
A T200-2 core needs too much windings, introducing large capacitance over the windings and more then halving the effective signal.

It is ferrite, no iron core, handles 400 watts on 7 to 30 MHz as I tried without the core heating up too much, on 7 MHz the core went luke warm with 400 watts carrier for 10 minutes.
You can for more power glue 2 cores together and lower the windings to 9 or 10 bifilar windings.
The 1:1 choke is also made of an FT 240-43 core with 2 x 5 windings of 50 Ohm coax on it after 5 windings cross over to the other side.
With 2 x 11 windings bifilar the inductance is 112.5 Micro Henry.

The Amidon powdered iron cores handle more power, but need double the windings to get anywhere near a working solution.
Even then the results showed the FT 240 - 43 core to be much more efficient in this contraption.
As choke it is actually quite ideal, one core with 2 x 5 windings will do legal limit but just...

Here 5 mm Teflon coax was used but loose winding RG 58U will work as well, though it will not stand heat as well as Teflon coax.

Cover the FT 240 - 43 cores with glass fiber tape the do conduct and the tape will protect your windings against sharp edges and isolate the core.
Chosing 25 feet is done to keep the length of the antenna as far as possible away from any resonant point on 7 - 29 MHz, be it 1/4 or 1/2 wave or even 5/8 wave.
Next post a few piccies of the 1:4 unun with FT 240 - 43 core Teflon wire and end result antenna.

Alternative feeding is with ladder line to the shack and use a tuner directly or balun and few feet of coax depending on the tuner you have.

[PA5COR]

Ok, trying to post the latest piccies, made a nice top from some alu wire to please the peasants.
1376313764

[PA5COR]

http://www.g7lrr.com/wp-content/uploads/2013/11//UNUN.gif (http://www.google.nl/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=http%3A%2F%2Fwww.g7lrr.com%2F%3Fpage_id%3D265&ei=5vcTVavBCoOHPcSSgNAN&bvm=bv.89217033,d.ZWU&psig=AFQjCNFjJvXpQQoE58gI8LB__rkVZukAsQ&ust=1427458402767264)

Do NOT use the T200-2 core, use the FT 240 - 43 core

Winding of an 1:4 UNUN.

[PA5COR]

Results from 40 - 10 with 2 radials of 30 feet on it now raised from the ground and the base 6 feet from the ground .

40 meter 1 ; 1.3 without tuner.
30 meter 1 : 1.8 without tuner.
20 meter 1 : 1.2 without tuner.
17 meter 1 : 1.7 without tuner
15 meter 1 : 1.5 without tuner.
12 meter 1 : 1 without tuner
10 meter 1 : 1 without tuner.
6 meters 1 : 1.1 without tuner.
4 meters or 70 MHz 1 : 1.5....

With tuner ( MFJ 998 and internal FT 2000 - D tuner very good tuning back to 1 : 1.

SWR measured with MFJ 269 antenna analyzer at the feed point of the antenna with 3 feet of coax.

Metric length of the radiating element 7.65 meters or 25 foot.

Since the radiating element makes physical contact to ground and the Imax 2000 radiating element does not but is capacitive coupled the 25 foot vertical has less noise from static sources.
Still I will put a 180 KOhm resistor over the radiator and ground 5 watt pressed carbon because I have a lot of them and they don't influence the swr and can handle lots of power.

Radials is the key word here mounted on the ground use lots of them mounted over the ground on the roof or 10 feet up minimum 4 radials of 30 feet, more and just over 1/4 wave for the ham bands if you have a flat roof.

For my inverted L of 77 feet high and 77 feet to the side I have 3000 feet of wire as radials in/on the ground or just above the ground.... tunable by the MFJ 998 legal limit tuner for 160 - 10.

[K7SGJ]

Well done, Cor. :clap:

[PA5COR]

Raining cats and dogs now, no outdoor antenna time...
Taking a shower and off to the shooting club now.

Just a last piccie of how to wind a 1:1 unun.
Numbers of winding not accurate, just for showing the how to do.

https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRS7MxtfFkHzeAay_J10C0UTNXmdSFT2 iC4xlWue4gdEpFlxjr4xw

[PA5COR]

http://zerobeat.net/G4FGQ/page3.html#S301

Some nifty DOS based programs for calculating things, works fine for me in experimenting.
At the bottom off the listed programs you find the L.V.D. proggi to calculate a vertical or inverted L length and effect on efficiency.

Using that program and my data the new 25 footer will have anywhere from 92 till 96% efficiency.
The chosen length also gives on most frequencies the expected 300 - 500 Ohm resistance the 1:4 unun can handle quite well.
For some bands like 18 I might have better opted for a 1:6 unun, but that would have reduced the 7 and 10 and 14 MHz bands because they are now close to 50 Ohms after the 1:4 unun, and that would become much lower, raising the swr there.

So, with the chosen length and unun choice this is the best middle of the road solution.

[NQ6U]

http://zerobeat.net/G4FGQ/page3.html#S301

Some nifty DOS based programs for calculating things [...]

DOS?? LOL!!

[K7SGJ]

DOS?? LOL!!


Dos ve donya comrade

[PA5COR]

I never said I wasn't getting old..... dang....

[NQ6U]

Dos ve donya comrade

Are you troll for Vlad, tovarish?

[K7SGJ]

Are you troll for Vlad, tovarish?

Nyet, comrade. He has me looking for moose and squirrel. Wants to use squirrel as drone over Ukraine, and moose for shirt rack.

[suddenseer]

Damn Cor, you are the short space antenna god! I usually have the real estate to run wires. This is awesome!

[PA5COR]

My "plot" is 100 feet long and 25 feet wide, on which is the house of 32 feet long and just as wide as the plot, row of 6 houses under one roof.

You get "artistic" building and raising antenna's that way, after my cleaning up this summer, only a disc cone antenna and the FD-4 OCF will stay as will the 5 element beam stay for 6 meters.

The Imax will be replaced by the nw contraption I'm now trying to get the best results out.
The Inverted L of 77 feet high and 77 feet to the side will sat as well.

The OCF is fit for 160 - 10, lengthened on the short side with coil and wire to resonate it on 160 as well, total length 150 feet now, stretched over 3 rows of housing estate.

The inverted L will tune from 160 - 10 with the MFJ 998 autotuner at the feedpoint.

2 and 70 beams will go, not used them in years, just as the Diamond X 510 replaced by the disc cone Diamond.
I'll be 63 this August, so I'm cleaning up the antenna's and since all mounting hardware on the roof is 316 L stainless steel I don't have to worry it will corrode.
With the storms we had the last years, I'm toning down the stuff on the roof, with me getting older I'm not planning to go on the roof every year now.

The new vertical is build like a tank, once up I don't have to worry about that one in a storm.
The other mast with rotor and beams will have less as half the wind resistance after the clean up and be much lower.

Wish I had the space for a few beverages for 160.....:(