[UK-CONTEST] Rotator choice/long rotator cable runs

[Paul Beecham]

Hello Simon,
I have used in the past 12 core  intruder alarm cable ( with the cores
doubled up to reduce voltage drop) at around 100m . The more cores
that can be utilised this way the better. This was used with a Kenpro
600 and a x7. This was a fairly cheap solution that worked OK but a
cable with the required number of cores and a larger csa is
preferred.I now use screened 6 core copper stranded  cable with a csa
of 1.5mm over 100m with out any problems and that drives a large
rotator ( pst 71 d ) and heavy yagi beam aerial.

You can use a readily obtainable 1.5 mm 3 or 4 core pvc  flex,  run a
couple of lengths for the number of cores that you need.

Remember that any long cables leading in to the shack act as receive
aerials and can bring in unwanted RF. These need to be de- coupled
with ferrite beads or similar as they enter the shack and don't forget
that the control box and rotator can get zapped so decoupling
capacitors here too if not already fitted.

The yaesu type of rotator ( Kenpro ) has proved reliable for some, but
their design is such that it struggles to brake or stop heavy loads
especially in windy conditions. In stormy weather  I have trashed a
Yaesu sdx 1000 turning a x7 to the point where the only recognisable
internal parts were the ball bearings.

Always put a rotator in a cage or other similar with a top bearing to
minimise side loading, you can de-rate your rotator considerably if
you don't.
Side and uneven loads will also make the rotator call for more current
and cause more of a volt drop on your control system.

Use the biggest rotator that your budget allows, my thinking is to use
a rotator the next size up from what the specs. say is satisfactory
for the wind area and weight of the load your turning. ( especially
true with SteppIRs )

Good luck with your installation.

73 Paul
G6PZ



On Thu, Oct 22, 2009 at 11:58 AM, Simon Jude <simon at simonjude.co.uk> wrote:
> Hi,
> Can anybody help?
>
> I'm about to setup an X7 tribander which I'd like to locate on a
> trailer tower in our field, upto 100m from my shack.  Having chatted
> with local hams and looked at the Yaesu rotator manuals there seems to
> be very little info about the problem of voltage drops over such long
> runs of cable.
>
> Has anybody on the list got a similar setup to the one I plan, and if
> so, have you had any problems with rotator voltage drops?  Are some
> rotators better in this respect than others?
>
> Any tips would be appreciated
>
> 73
>
> Simon
>
>
> --
> http://www.g7soz.net
>
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