The AM Forum

As I read through the many pages here and elsewhere, my mind drifts back to a subject that is in constant flux, my Butternut HF6V up @ 16' on the roof.
While it works pretty well, I am still frustrated by the fact that it is a major compromise and those
damn coils expand and contract all of the time, making life maintaining the thing too time consuming. I also don't trust any doorknob capacitor 6kv and below. Now that AM Fone is on my personal horizon, the whole thing needs to be scraped in favor of something much more robust.
I have the materials to build just about anything but I keep thinking about a broadband monopole.
It sounds whacky but maybe you sages here could visualize this: A 32' ft. vertical that has 4 horizontal spreaders on top that resemble a top hat. These extend out X number of feet (not sure of the distance yet) and from there, 4 individual conductors are dropped back down to a similar spreader near the bottom but secured with insulators. The result ends up looking like a cage of sorts but is actually folded back onto itself. Add the necessary series inductance and parallel variable cap and tune to taste. Electrically, it would resemble a 1/4 wave vertical, no?
The same 1/4 wave counterpoise would be used, via a DC coil just like the Butternut.
As I am not an engineer, I am cobbling together ideas from books and actual antennas used.
My particular plight is one of improvement through experimentation. I also hate the idea of spending big money on something from DX Engineering or SteppIr when I have the materials on hand already.

why not just go with an inverted L if you want a vertical antenna?

I have a very large obstacle in our yard, a 40 tall Chinese Elm tree that isn't antenna friendly. Our lot size is 30'X 90' and makes for a pretty challenging place for antenna projects. The roof mounted vertical has so far been the most successful system. I should also point out that several of the houses within my immediate vicinity are 3 story "Faraday Cages" that attenuate really well unless the antenna gets some serious elevation. Fortunately I don't have to contend with CC&R's here in the Venice Canals.
My only restrictions are available supports in the clear. Look up my address on Google Earth via my callsign at QRZ. An aerial view of my QTH will confirm this for your eyes.

that has to be the biggest tree i have seen as far as how big around it is.

nuff said..


..sk..

Tim, how far aboveground is your top support in this diagram? :)

..mike..not sure what you mean, by top support..the dwg is basic, made yrs ago...it was strapped to a 2x4, pounded in the ground...the current one, is a light-weight tv tower, mounted on a wooden pallet, and is guyed with rope, at about 25ft above the ground...a friend built the same kinda thing, mounted about 25 ft up, attached to his garage...thing werks really well, and thinking about it, rather cheap...my cost was time, and 6 dollars in post hole cement..that is how the current one is...sitting in a large plastic pail, with the cement...the pic shows the vert...there are 2 inverted "Ls" you can see in the pic..one fer 160, the other, 75...there are 2 "yard arms" supporting the "Ls"..one at the top, the other near the bottom..
..tim..

..sk..

mike, re-reading your post...well, as i recall, the original was at abt 30ft...whereas, the current one is at abt 28ft...the tower i use now is shorter than a quarter wave on 40...you will notice in the pic, a "stinger", which is both mechanically, and electrically connected to the tower, to bring it up to the measurements, of a 1/4 wave, for 40....

..tim..

..sk..

Do you mean something like this?

Somehow, for the originally-cited height of 32.8 feet, I was thinking somewhere around 24-to-26 feet for the upper "yardarm."  Just seeking a ballpark figure from experience, your photo helps.  Looks good, thanks!  ;D

..mike..the thing really works well...when i switch from the 160m loop, to the vert., on 160/75, or 40, you notice a huge difference in signal strength...the locals on 3725 are full scale on the loop, then on the vert, almost gone...

..tim..

..sk..

On your antenna sketch:
Since the three vertical members (the two vertical wires and the pole) are electrically connected at the base(coax input) why not just eliminate the two vertical wires and attached the horizontal wires directly to the top of the vertical pole. Seems to me you would wind up with the same electrically equivalent antenna with no vertical wires, no insulated rope, no need to measure and retain specific distance separation between the vertical wires and the pole.

Hi Pete
The two vertical sections are part of his "L" antennas. The main vertical mast is resonant for 40M and as Tim feeds 160 or 75 through a tuner the "L's" will accept RF and radiate.
I'm building a similar antenna, where my mast is resonant for 40M. I am going to use a vacuum relay to switch RF from the 40M mast to the 160M tuner located at the base to the inverted "L" wire antenna Both antennas will share the same vinyl coated welded fence radial system.

Fred

I would like to hear how that works for you Fred.

N6YW, Cannot see your name in QRZd
You will not have room for the "Ls". Frank "The Slab, Bacon has a posting about a very short dipole that works down to 160M. You will have to build a tuner and suitable balun/matching transformer for it.

http://amfone.net/Amforum/index.php?topic=12710.0

Shortened Antenner That Works.......the first post from Frank "The Slab Bacon"

In this link you will see a PDF file. Click on it and see how this antenna can fit on your property.

Frank
I'm not sure why you can't see my name on QRZ. It's William "Billy" Yates.
The twin marconi link I posted can fit on my property if I bend it here and there.
My water table is at 3' ft, not to mention the entire Canal system and the conductivity
it quite good. As to the L configuration, I could base load a 32 ft mast and then add
a horizontal section of wire back over the tree to another mast which would put me
right around 60' ft. long...that would be about 90' total. The inductance could make
up the difference. I won't know until I try.

pete..if i were to do that...it would not work...it is the same idea of a fan dipole....but, standing on it's end..on it's own, without the use of a tuner, swr is flat on 1880, 3725, (the 2 Ls), 7290, all of 15, and all of 6...

..sk..

..hy gain brought back this design from the 60s...very simple, and much like mine...it uses wires in parallel to the feed, for each band, and "doubles-back" the 75m wire, whereas i send mine out as an inverted L. same for 160..

..sk..

I wonder what happens to the pattern when you fold those 4 radiators like that.
Thank you for posting this. By making each of those legs a different length, it could
become a multi-band vert. Interesting.

I was just trying to understand what you described. I also like the hy-gain shown above. I'm willing to try different things like folding and the previous article showing the 60FT span dipole folded on itself because I can't tune 160 efficiently with what I have and my space is also limited. I have little experience with large ham transmitting antennas so these topics are very valuable to me.

Tim that HyGain antenna looks mighty tempting...................I got to restrain myself...........I'm almost ready to make some radio........I never trust my design.......no confidence, I guess.
I do know that for $40.00 I built a copy of your design.......sooooo I'll give it a try. My version will not have 80M.
Just 40 and 160

Fred

Slightly off-topic
Hi Billy
I just checked my own call and QRZd no longer display name and address of Ham op. You would sign in to get email address............now there is less info available.
Fred

ok fred, well the idea was to present a design that is similar
..i'd never lay-out that kind of money...but, you can put other wires in parallel...20/17, 30, whivhever...

..sk..

Don't let a lack of confidence get in the way! It makes it more interesting.

Go to QTH.com and get the callsign addresses. I believe I saw your picture on the cover of Electric Radio a few years ago, Bill.

Yes indeed, I made the cover of Electric Radio. Issue 179 in April 2004.
That's the world famous "Heathkit Junkie" Bill Brandenburg,W0QNI (SK) and I putting together one of our many Heathkit stations during our twice yearly retreats. He was a dear friend and he willed his entire collection of Heathkit's to me, which made me (arguably) the owner of one of the world's largest private collections of Heathkit's.
It was an honor to know him. I have since taken his place as Net Manager for WARFA.