One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Clearly there would have to be some mechanical support other than
just the co-axial coupling to withstand the wind storms that we are all
now experiencing?

On 1/30/2016 6:04 AM, gareth wrote:
One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Clearly there would have to be some mechanical support other than
just the co-axial coupling to withstand the wind storms that we are all
now experiencing?



Rotary Transformer
These will keep you occupied for a while.

http://coefs.uncc.edu/mnoras/files/2...Chapter_19.pdf

https://www.pes.ee.ethz.ch/uploads/t...r_APEC2013.pdf

http://www.fdk.co.jp/cyber-e/pdf/RT-RTE001.pdf

Mikek

"amdx" wrote in message
...
On 1/30/2016 6:04 AM, gareth wrote:
One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Clearly there would have to be some mechanical support other than
just the co-axial coupling to withstand the wind storms that we are all
now experiencing?
Rotary Transformer
These will keep you occupied for a while.

http://coefs.uncc.edu/mnoras/files/2...Chapter_19.pdf
https://www.pes.ee.ethz.ch/uploads/t...r_APEC2013.pdf
http://www.fdk.co.jp/cyber-e/pdf/RT-RTE001.pdf


Ta, but not what I had in mind, which was a rotary co-axial joint

On 1/30/2016 9:51 AM, gareth wrote:
"amdx" wrote in message
...
On 1/30/2016 6:04 AM, gareth wrote:
One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Clearly there would have to be some mechanical support other than
just the co-axial coupling to withstand the wind storms that we are all
now experiencing?
Rotary Transformer
These will keep you occupied for a while.

http://coefs.uncc.edu/mnoras/files/2...Chapter_19.pdf
https://www.pes.ee.ethz.ch/uploads/t...r_APEC2013.pdf
http://www.fdk.co.jp/cyber-e/pdf/RT-RTE001.pdf


Ta, but not what I had in mind, which was a rotary co-axial joint




http://www.macartney.com/what-we-off...50-and-75-ohm/

http://www.schleifring.com/ship-radar/

https://www.asianproducts.com/produc...ings-meet.html

http://www.moog.com/literature/MCG/AC6355DS.pdf

http://www.moog.com/products/slip-ri...psules/ac6305/

http://www.slipring.com/series-high-...-273-l-en.html

Power levels could be a problem.

gareth wrote:
One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Sounds like a $200 solution to a $0.75 problem, i.e. an extra foot or
two of coax to allow slack for turning.

--
Jim Pennino

On 1/30/2016 1:24 PM, wrote:
gareth wrote:
One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Sounds like a $200 solution to a $0.75 problem, i.e. an extra foot or
two of coax to allow slack for turning.

I think the issue is that you have to manage the turning so you don't go
too far in either direction before reversing.

--

Rick

In rec.radio.amateur.antenna, you wrote:
gareth wrote:
One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Sounds like a $200 solution to a $0.75 problem, i.e. an extra foot or
two of coax to allow slack for turning.

With 4 different yagis on the mast, a large, bundled loop of
coax(es) *HAS* to be The Way To Go.

Jonesy W3DHJ
--
Marvin L Jones | W3DHJ | W3DHJ | http://W3DHJ.net/
Pueblo, Colorado | @ | Jonesy | __
38.238N 104.547W | jonz.net | DM78rf | 73 SK

"rickman" wrote in message
...
On 1/30/2016 1:24 PM, wrote:
gareth wrote:
One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Sounds like a $200 solution to a $0.75 problem, i.e. an extra foot or
two of coax to allow slack for turning.

I think the issue is that you have to manage the turning so you don't go
too far in either direction before reversing.


Most ham rotators will not go much over 1 turn. Some will go about 1 and a
half. If you offset the coax about half a turn it does not have to flex all
that much. That is if the beam stops to the north, turn the beam south and
tape the coax to the mast and then go to the other side of the tower and
tape the coax there. Be sure to leave plenty of coax for the antenna to
turn.

rickman wrote:
On 1/30/2016 1:24 PM, wrote:
gareth wrote:
One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Sounds like a $200 solution to a $0.75 problem, i.e. an extra foot or
two of coax to allow slack for turning.

I think the issue is that you have to manage the turning so you don't go
too far in either direction before reversing.

Commercial rotators only turn +/- 180 degrees.

If you are building your own, adding limit switches is far simpler,
cheaper and more reliable than a rotary coupling.

As the supply of WWII and Korean war prop pitch motors has pretty much
dried up and they cost more than a used commrcial rotator ready to go,
I don't see much motivation for building a rotator from scratch these
days.


--
Jim Pennino

On Sat, 30 Jan 2016 12:04:49 -0000, "gareth"
wrote:

One of the problems with beams is the cable winding around
the mast if you try to turn too far in one way or another.

These difficulties have long been solved in the world of radar,
so, has anyone conceived of an infinitely rotatable 50 ohm
coupling for our beam antennae?

Clearly there would have to be some mechanical support other than
just the co-axial coupling to withstand the wind storms that we are all
now experiencing?

"Slip rings".
https://www.google.com/search?q=slip+ring&tbm=isch
https://www.google.com/search?q=coaxial+slip+ring&tbm=isch

For coax cables, it's a "rotary joint".
https://www.google.com/search?tbm=isch&q=rf+rotary+joint
I like to use a balun to go from coax to a parallel transmission line,
then to slip rings, and then to a dipole antenna feed. I once built a
direction finder that used a rotating yagi antenna, using that method.

As amdx mentioned, RF power levels are going to be a problem. My
interest is in direction finders, which normally do not transmit. If
you're going to run RF through the rotary joint while rotating the
antenna, the RF is going to arc and burn a nice neat groove in the
contact area. If the rotary joint is locked in place, it might
survive at low power levels.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558