Coax around a rotator

[VK5APN]

All

So you have installed your tower, found and installed the fatest Heliax, now what do you use to get around the rotator? Is it just a small flexible piece which then goes onto other low loss cable to the antenna up the rotating pole? How many connectors do you use. If the latter mentioned is used then there will be 6 connectors between rig and antenna. How much loss do you expect from a connector (0.1dB??)

This needs to be low loss yet flexible enough not to break too regularly. Is FSJ-450 OK or too "stiff"? Other cable that comes to mind is RG213, LMR400 Ultra flex....

What is the best route method? A curvy cable around the rotator or a big hanging down loop?

Any hints appreciated and photo's a bonus. Getting my mind around this ready for when the opportunity arises for the installation to occur. SOON I HOPE.

Thanks in advance

Wayne VK5APN

[VK4QB]

Hi Wayne,
There is nothing much you can do about the connector losses except measure them (all together)and see. I think that you will probably find that some brands have more losses than others. I have never seen any loss figures on connectors, but there must be some and as you say it will probably pretty low, but it all adds up. On 6 metres I use UG231 from the set to the base of the rotator and then RG58 there on to the antenna(about 5 feet) this is flexable enough for many years as it is rapped around the short mast twice to allow it to flex over a longer length. Yes, there is losses but if you change it back to RG213 again you will probably end up with more losses.
Its all a compromise.
Brian 4QB

[VK5APN]

Brian

Thanks for the reply.

I forgot to mention that the set up (hopefully) would be for 144-1296MHz. At 1296MHz the losses will add up alot quickly than say at 2m.

Regards

Wayne

[VK2GOM]

Hi Wayne,

Can you not run one continuous length, and anchor it at the base of the rotator, the have a large 'drip loop' with enough slack to allow the coax to revolve around a turned mast a full turn. The coax would be re-anchored above the rotator, and clipped to the mast/boom on its way to the antenna. You could even rig up an insulated 'stand-off' at the bottom of the rotator to hold the coax out a bit, to ensure no tangles/snags.

At least that way there are no connectors/joints and you can pretty much calculate your feedline loss from the coax manufacturer's specs and length you use.

73 - Rob VK2GOM / G0MOH

[vk3six]

All

So you have installed your tower, found and installed the fatest Heliax, now what do you use to get around the rotator? Is it just a small flexible piece which then goes onto other low loss cable to the antenna up the rotating pole? How many connectors do you use. If the latter mentioned is used then there will be 6 connectors between rig and antenna. How much loss do you expect from a connector (0.1dB??)

This needs to be low loss yet flexible enough not to break too regularly. Is FSJ-450 OK or too "stiff"? Other cable that comes to mind is RG213, LMR400 Ultra flex....

What is the best route method? A curvy cable around the rotator or a big hanging down loop?

Any hints appreciated and photo's a bonus. Getting my mind around this ready for when the opportunity arises for the installation to occur. SOON I HOPE.

Thanks in advance

Wayne VK5APN

Tie it of with tape and cable ties about half meter out along boom of lowest antenna.

Loop 1 metre


and tie off on the towerl leg below rotor.

Allow clearance between boom and tower so the cable does not get scissored.

USe RG213 fly leads to the better feedline cable.

Warp cable tie points with nitto tape (black) Dont pull cable ties too tight or you wil intorduce discontinuities.

Use black u/v inhibited cable ties.

Make it easy to get at and repair.

QED

[VK5AJL]

My solution is to put the box of amplifiers at the bottom on the rotating piece of my tower. Heliax from amps to antennas, rg213 from amps to radios but my situation is a little different to most. I have also seen a horizontal loop of heliax which wraps up closer to the pole in one direction but pokes out further in the other.

[VK5APN]

All

Thanks for the info guys. Great bunch and full of useful ideas. You have been there done that. Ta

OK will investigate the ideas given here. A staff college also suggested placing the coax in irrigation tubing to add a so called strain relief in the loop, so that the coax cable does not get too much of a radius bend at the boom with its own weight.

Thanks heaps

Wayne

[VK4APN]

All

Thanks for the info guys. Great bunch and full of useful ideas. You have been there done that. Ta

OK will investigate the ideas given here. A staff college also suggested placing the coax in irrigation tubing to add a so called strain relief in the loop, so that the coax cable does not get too much of a radius bend at the boom with its own weight.

Thanks heaps

Wayne

See http://www.southgatearc.org/atv/zebedee.htm

I have used this set up for about a year now - so far so good. I have changed the rotator during this period to a "proper One" not the TV type in the picture.
I have 2 feeds (cellflex version of ldf 450) in the spiral for 70cms &1296mhz. The transverter for 1296 is located at the base of the mast with lmr400 to the tcvr. So only 2 connectors on each run - at each end of the cellflex.
So you are essentially adding a little length in the coax as a trade off to adapters, higher loss coax around the rotator and additional connectors. If you think about it - if you "dress" the cables correctly then you are rotating only 180 degrees each way.
I was concerned about the arrangement initially, but after careful inspection and months of use I am a happy little vegemite.

I know the purists will disagree - what can I say it works for me.................

[VK5APN]

Paul and others

Great article, and the picture is worth a 1000 words. The article makes sense and is logical, will be going down this line. Ta

Thanks guys for all the help and guidance

Wayne

PS Paul, love the call sign