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Old 2011-12-09, 02:31 AM   #61
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cone from can - approx 6 1/2 tall x 2 1/2 inch diameter at bottom.

A simple attempt to make an AL cone for a Biconical antenna element for experimentation.

Tall beer can. Cut top off carefully w/box cutters.
Take good scissors and 2 opposite cuts lengthwise, and then then cut out two narrow wedges.
Folds naturally into a cone. Secure end with tape to hold shape.

( it is to laugh ! ... errrp. )
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Old 2011-12-09, 02:33 AM   #62
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Quote:
Originally Posted by ota_canuck
I believe that those biconical designs that you've linked to may have characteristics of their own that would require completely redesigning the reflectors/spacings/phasing, etc...
Yup - it's a whole new antenna research and experimentation exercise.

... errrp .
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Old 2011-12-09, 08:27 AM   #63
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If you want to make the whiskers longer you don't have to worry about staying within the reflector width just make them longer. If the phase line spacing is wider the whiskers should to be shorter or visa versa it's not a 1:1 ratio but it does have a large effect.

Solid elements like the conical and even flat sheet metal bowties appear to resonate at a lower frequency than wire whiskers of the same length so those do make good options for mechanical size limitations.

One word of caution if the size of the bowtie part of the antenna gets within a certain range it will start to become a more effective VHF-HI antenna and may start to interact poorly with the folded dipole.
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Old 2011-12-09, 08:59 AM   #64
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Default Home Made Biconical examples - web link

As this web link shows, do it yourselfers have certainly made biconical antennas before.

I too imagined this way of making one - by simply soldering some copper wire in a cage shape.

And sure enough it has been done.

Some basic lengths / dimensions are also shown.

http://www.civilianaviation.co.uk/fo...hp?f=71&t=2138
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Old 2011-12-09, 09:51 AM   #65
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Quote:
I too imagined this way of making one - by simply soldering some copper wire in a cage shape.
Thats too much work. Rat wire can be made into a cone easily and soldered.

Quote:
Tall beer can.
Bud also comes in the 24oz can. There are also taller and wider beer cans from Australia and Japan.
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Old 2011-12-09, 10:35 AM   #66
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Ever seen these?

"Conical Plant Support Cage" "Plant Support Rings"

http://www.greenshorticulture.co.uk/...-Support-Cage/

Not sure if they are also known by other names in North America.

I see them thrown out sometimes. A little rusty.


Oh yes, and here are some Galvanized ones:
(Web Search for CANADA )

Coastal Growers

http://www.coastalgrowers.ca/store/i...ato-cages.html

"Tomato Cages" "Tomato Tower" - Galvanized steel ones.


Manchester Products - Garden and Pet

http://www.manchesterproducts.com/vi...p?id=DON708073

"Galvanized Tomato Cage" - 3 different sizes shown
1. 16x54"

Glamos Wire Products, Galvanized Tomato Cage

2. 12x33" - says 3/16" diam wire
3. 18x54"
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Old 2011-12-09, 11:34 AM   #67
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Quote:
Originally Posted by 300ohm
There are also taller and wider beer cans
What about Steel?

Stronger but harder to work with, less conductive, but anyway:

For making the smaller UHF cone:
(The larger VHF is probably better built in a wire frame).

1. Paint Cans?
I was also thinking about Paint Cans (buy new empty clean ones).
Because they might be near the right size for UHF. Shorter and wider.
Quart, litre, gallon size?

They are made of chrome plated steel - stronger.


2. Round Air Duct Tubing?
Also thinking about galvanized steel round AIR DUCT tube.
(I think I have a short length of some scrap 4 or 5 inch diameter)

Bought in lengths - fairly inexpensive - could make UHF cones easy.
Easily found as scrap.

In both cases - cut, form cone and rivet.


[ Side note: mounted vertically - these BICONICAL antennas are OMNI-Directional - to the horizon it says ... they may not have much GAIN - but for a local, wide band RECEIVE ALL antenna - may have their uses. )
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Old 2011-12-09, 12:25 PM   #68
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Coffee cans take a bead of solder quite nicely. I use a propane torch with a soldering tip.

http://www.qsl.net/v/va3rr/dualmode/dual_mode.htm
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Old 2011-12-09, 01:50 PM   #69
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I made my first M4 last june using those galvanized rods from plant supports bought in a Dollar Store.


I wouldn't use beer cans but I could help you drink them

I went to an electronics surplus store yesterday and now they sell 4 bay and 8 bay antennas; same brand Kross, but not in kit form like the one discussed in this thread.
.
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Old 2011-12-09, 04:43 PM   #70
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Quote:
Ever seen these?

"Conical Plant Support Cage" "Plant Support Rings"
Yep. Too pricey for the good ones to hold my tomato plants, I usually plant around 125, heh. The cheaper thinner wire ones buckle too easy. But I did buy a quality one of those this spring to hold the last of my aspergus plants.

I tie up my tomato plants with the bamboo I grow. If treated by letting the bamboo absord a 10% boric acid solution after cutting (with the leaves on) for about 2 weeks (kind of like with cut flowers), the bamboo will last in the ground a good 3 years.
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Old 2011-12-10, 12:06 AM   #71
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I bought the KROSS model GY-TVA 003 a couple of months ago when I came across it at Factory Direct for $15 bucks and I figured what the heck..it's dirt cheap..let's see what it can do. It was missing the assembly instructions in the box, but I found the YouTube installation video and put it together.

I had the same problem where the plastic frame bends backward near the top and bottom edges.
Anyway once assembled, I played around with it for awhile. I had it pointed southward out of a 2nd flr bedroom window and got pretty good reception results. I got all of the Toronto stations and the main Buffalo stations too at about 80% signal strength.

Shortly after I got ahold of an original CM4221 and could make some direct comparisons. The CM4221 was a touch less effective at receiving the Toronto stations(probably due to it's slightly better directionality), but was noticeably better in receiving the more distant main Buffalo networks which came in averaging 90%. An additional channel that the Channel Master could bring in, that the Kross could not, was the hard to get 51 ION.
The VHF dipole did not do me any good...could not get CHCH 11 from my location.

It's a serviceable antenna and with it's relatively compact size, could be a good solution for indoor use.
However it is kind of frail with some of the reflector rods loose and could pop out relatively easily if mounted outdoors exposed to the winds/elements. One section of VHF dipole does indeed pop out of the plastic frame and I need to tighten it down with a plastic tie.
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Old 2011-12-11, 07:09 AM   #72
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Recent posts - all very interesting and informative.

Yes - demonstrating that many improvisations are possible with easily available materials. Thank you everyone for showing those examples (!)

( Soldered coffee cans as Satelite Feedhorn / Circular waveguide ... I saw something like that in an ARRL book. Marvelous example!)

Yes - the KROSS antenna elements snap together into the plastic frame like a LEGO set - not so sturdy for outdoors - worked well enough indoors. Spine bends a little - all could use some re-inforcing.

But since the plastic frame is a "snap together" implementation - that could be used as an experimentation platform. Or you could do some ONE-OFF modifications, and place such an antenna separately somewhere in a HOTSPOT (ex - attic) to receive that "extra" channel that you need a separate antenna for.

ie. Build some reflector rods and whiskers of specific dimensions and snap them in ... to recieve that one channel you wanna get, but off in a different direction to your main antenna.

Lots of possibilities.

So my latest imagination is a large-ish vertically mouted, wire frame, bi-conical antenna - omnidirectional - and wideband to receive all: VHF lo - FM - VHF hi - and UHF. Attempt to get all locals easily with one simple antenna. Wonder if it is possible.
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Old 2011-12-11, 01:03 PM   #73
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Quote:
Yes - the KROSS antenna elements snap together into the plastic frame like a LEGO set - not so sturdy for outdoors
Like in the install video ota_canuck posted, a lot of people would use UV resistant wire ties to hold the reflector rods in place. They probably should have included them in the kit.

Quote:
So my latest imagination is a large-ish vertically mouted, wire frame, bi-conical antenna - omnidirectional - and wideband to receive all: VHF lo - FM - VHF hi - and UHF. Attempt to get all locals easily with one simple antenna. Wonder if it is possible.
You would probably need two, one for VHF/FM and one for UHF, connected together either by a correct length piece of twin lead or a UVSJ or twin lead band splitter used in reverse.
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Old 2011-12-12, 09:16 AM   #74
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I just GOOGLE searched:

Egg Beater pics -AND- Umbrella Frame pics

I think both of these household items approximate a conical wire frame shape.

Hand egg beater
- is tapered, small / medium sized and has the "rounded / semi-spherical end" already built into it.

Umbrella frame
- is like a foldable and adjustible cone shape and a little larger in size.
- generally lots of broken umbrellas around, discarded everywhere
- might make good candidates for easy practical experimentation
- free and cheap

... of course - metal FUNNELS. They're pretty WIDE cones.

( the whole improvisation / scrounging / re-use thing - I find quite hilarious ...)
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Old 2011-12-14, 08:21 AM   #75
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Default Cone Type antennas or elements. ex Biconical or Discone

Starting a new Thread for CONE type antennas or elements.

Theory, Formulas, Builds, Experimentation, Modelling, Reception results - anything related.

Biconical - a dipole made of two cone shapes.

and there's also a Discone (disc + cone) which is a variation / special case of the biconical where one of the cone angles is increased till it becomes a flat disc.

Discone - a disc and a cone.
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