Helical wound vertical for Top Band!

[AE1PT]

It's feast or famine... I am either looking at doing nothing--or a dozen different projects. Maybe it is the prospect of being cooped up all winter???

160M has always seemed difficult to me--but had a tremendous allure. I had the room and trees a few QTH's back to run a flat top--but that is now out of the picture. Looking at options for an L or vertical for my current (and likely last) QTH, I ran across this:

http://www.hamuniverse.com/k6mm160metervertical.html

I immediately got a ham woody.

Anyone have any experience or general thoughts on this design?

[NQ6U]

A friend of mine made one of these for me. It worked well for the local nets and out to couple of hundred miles or so but I had no luck with DX. Of course, I only had 100 watts out but I found that the limiting factor for me was mainly on the receive side. It picked up a lot of man-made noise and I live in a rather RF noisy area. I know you can run a KW out and live in a rural area so you may have better luck.

One cool thing about the design: they work like a Tesla coil. The friend who made mine put 500 watts into his and got a nice ionization corona every time key keyed his mike.

[WØTKX]

The band intrigues the heck out of me too. The SK Elmer who's call I hold was a 160 "nutcase", and I helped him make a bunch of interesting antennas for that band in the 70's. Learned a lot, and would enjoy getting on top band to honor these memories.

Had some fun on 160 a few years ago when I had the room for a half wave OCF dipole. Never ran power, but I was able to talk coast to coast on SSB and made a few CW DX contacts. It was about 80' up in the air over very poor rocky soil. My little Ten Tec Omni D into a tuner did quite well for "barefoot" on 160. Surprisingly well. Of course being in the country near the continental divide at 10,500 feet didn't hurt. It was pretty quiet.

I have seen the article you linked to in the past, and saved as a possible solution. Also have stashed away four sturdy 4" diameter 6' mailing tubes that would do well if I coated them with epoxy paint and wound wire around them. But I never tried it... still might.

The new place has room for a full sized half wave dipole as well, and that is what I will be putting up... probably by next week. It will be lower... about 50-60' up in the air, same kind of rocky soil. Thing is, that makes a killer multi-band antenna up to about 20 meters or so, where it starts to really "lobe out", the petals of gain are hit and miss. But that's OK, as I really enjoy 75/80, 60, and 40 meters in the winter. But this large of a dipole would let me play on 160 again, even with an amplifier.

Might put up a full sized loop instead, but need to put up my Gap antenna as well. So the dipole will probably do for now, due to time constraints. I've gotten used to having the horizontal and vertical choice for antennas. But the loop would be better, I ran one that was about 440' total length for quite a while, and it was pretty amazing as a multi-band antenna. A bit short and "touchy" for 160, so I didn't run power.

Also have an HF2V that could be modified with a large wire "top hat". Have the 160 coil, but it won't take any power and would want to modify it so it could, which means a beefier coil. Those big mailer tubes might come in handy for that. Thick wire, large spacing, and mess with the antenna analyzer to get it dialed in. But I don't think I'll have time to do that before winter sets in. At 8500' elevation, I only have a few more weeks to get antennas up. Loops are a bit more work, and the trees are close together.

With any luck, I can join you and others there on 160. As the article says... no excuses, MMMMKay!

[W9WLS]

I built one of these a couple of years ago, as Carl stated they do work but as stated.

The corona shows up out here in the stick's even at a hundred watts, but it work's.

[PA5COR]

If you look on my bio on qrz there is a piccy of my helically wound vertical i went for first, 45 feet high it was too.
Replaced it with the 23 meter high inverted L now fed with a MFJ 998 autotuner at the bottom used for 160-20
The antenna section here must have a thread about it too here.

;)

Do use 1/2 wavelength wire to wind the helical, start with more space at the bottom between the windings and less space on the top.
You will get the max current as high in the air then, use a good ground system too, i have 3000 feet of copper wire in/on the ground here.

[KC2UGV]

I was just about to ring for Cor. I recall his build thread for that antenna.

[N8YX]

Do you have any trees nearby? If not, proceed with the helical plan. I would attempt to make the capacitance hat at least 6 feet square if at all possible.

Should you have trees...build a center-loaded, cage T or Y-top. The vertical element length will be determined by the highest set of branches into which you can get support ropes - and the horizontal length (capacitance hat) should be at least 20ft per side. Cage construction will be used for the vertical portion of the radiator in order to maximize bandwidth; 6-8" spread by means of Plexiglass or similar homemade insulators spaces 3 #12-#14 AWG stranded wires. Use a thicker one for the very top, where the capacitance hat begins as it'll be under a good amount of load.

Figure out the horizontal/vertical dimensions along with radiator diameter then plug those into your favorite antenna modeling program and find out what you'll need in the way of a loading coil. I would use a piece of Pi-Dux in as large a diameter as I could find; 1" to 1 1/2" OD PVC pipe will serve as a coil support to attach the vertical radiator sections. Model the coil placement and resonant frequency so it's just a bit higher than "center" and is at the top of the band segment you wish to use.

Next, use the same model to figure out how much of a base loading coil you'll need to cover the lowest operating frequency on which you plan to operate. Build the load coil using similar PiDux/PVC construction then source a few surplus vacuum relays. These go into a waterproof tuning box, are connected to tap points on the coil and are used to progressively short it out via shack-sited controller as you wish to go higher in frequency. Feed the antenna at the bottom of the base load coil.

I would also stagger-tune the radials instead of cutting all of them for one frequency. This goes for both self-supporting and tree-supported versions of this project. Key to making this project work is to put lots of them down, of course.

[AE1PT]

WHUT?????????

Muddling programs? Vacuum out my relays? Get loaded before I wind my coil?

Break out the puppets and crayons--I like to keep antenna's real simple...

[PA5COR]

Coils belong up high not at the bottom, too much loss where the max current is....

The helically wound vertical is a monobander, one reason i ditched it for the inverted L and autotuner at the bottom feed at the antenna.
It worked quite well, gave me the first qso's to Canada and the USA but the inverted L is higher, less lossy and about 6 - 8 dB better.
Get as much radials in at the feedpoint, anything in or on the ground will be detuned anyway, just cover as much ground as you can near the feedpoint where you have the most losses, my radials are from 30 feet long to one 300 feet long runnng in an U around the block of houses i live in.
Some are 4 inches above ground intertwined in the garden wood separation some run under the laminate in the house, under the house, through the front yard, etc.

At the feedpoint a 10 feet copper tube is in the ground and a 200 KOhm resistor connected to the Inverted L for static bleed off.
Several other 10 -20 feet copper tubes in the silty clay form the rest of the grounding one connected to the station with a large wire of 6 feet.
The house ground circuit is also connected to the grounding system, so that the kitchen sink is part of it as all copper piping etc.

I regularly put 1000 watt into the helically wound vertical, no corona, at the top i had a T hat with 2 wires of 30 feet long.

The Inverted L is 23 meter high, and the wire from the top to a tree is also 23 meter long, non resonant on 160 but that was done on purpose to prevent it from being a 1/2 wave on 80 with high impedance.
The MFJ 998 autotuner has no problem tuning it from 160 -10 with 1000 watts in, though the radiation pattern above 20 meter leaves a lot to desire.
There i use the OCF ( Fritzel FD-4) or the Imax 2000 from 17 to 10.

For 160 and 80 the inverted L is for DX a lot better as the OCF antenna.
40 and 20 depend on the conditions, i can swicth over easily with the heathkit antenna switch to see what antenna works the best at that time.
The helically wound T wll have a vertcal radiation, an inverted L also has a horizontal component.
Depending on the band and where the current is the highest you will get a mixed component sometimes mostly vertical and low angle of radiation, good for DX.\
The Helical had a pronounced dead zone after the groundwave and after 300 miles the first jump hit the ground again, the inverted L has a less pronounced dead zone.
THe inverted L has a groundwav extending daytime from 90 to 200 mies for good stations with a decent antenna, nighttime propagation for me is Europe up to 6000 miles easy and the USA and Canada, wintertime is the best for us, less atmospheric noise on the northern hemisphere.
Though i did work some nice DX in summertime as well.