[TowerTalk] Rotor Cabling Query

[Lux, Jim]

On 4/3/21 5:42 AM, Joe Subich, W4TV wrote:
>
> On 2021-04-02 10:38 PM, Kelly Taylor wrote:
>> For such a length, would installing the motor-start capacitor, 
>> normally inside the control box, nearer to the rotor help?
>
> The capacitor is not a starting capacitor.  The Hy-Gain motor requires
> a phase shift between windings to run (a capacitor run motor). The
> direction of the phase shift determines which direction which direction
> the motor rotates.
>
> However, yes, installing the motor-run cap at the top of the tower will
> reduce the voltage drop to the motor by about half, particularly if
> the freed up wires are then used to double up on 5 and 6.
>
> 73,
>
>   ... Joe, W4TV
>
>
> On 2021-04-02 10:38 PM, Kelly Taylor wrote:
>> For such a length, would installing the motor-start capacitor, 
>> normally inside the control box, nearer to the rotor help?
>>
>> 73, kelly, ve4xt
>> Sent from my iPhone
>>
>>> On Apr 2, 2021, at 18:54, Joe Subich, W4TV <lists at subich.com> wrote:
>>>
>>> 
>>>> A primary point/concern of my post is the length of the run on the 
>>>> temporary 300 ft and to the final goal of 700 ft. What size of the 
>>>> conductors/wire/cable to utilize for the effort. Some part being
>>>> heavy duty 8 conductor rotor cabling in conjuction with splices
>>>> and/or runs of UF solid wire cabling from 14 gauge to 10 gauge such
>>>> as 14/3, etc. or other such ideas on conductor size.
>>> You will need to figure out those trade-offs for yourself in your
>>> particular installation.
>>>
>>> The brake solenoid in the Ham IV/T2X is rated 24 VAC @ 5A. The brake
>>> uses wires 1 and 2 (the "heavy" wires).
>>>
>>> The motor in the Ham IV/T2X is rated 20 VA @ 2.25 A.  The motor uses
>>> wires 4, 5, 6, and 8 plus wire 1.  Rotation power is supplied to either
>>> 5 (rotate right) or 6 (rotate left).  4 and 8 are the capacitor
>>> connection and the return in wire 1.
>>>
>>> To energize the brake you have the voltage drop of (0.75 Ohm + the
>>> resistance of wires 1 and 8) x 5 A.  To turn the motor you need to
>>> overcome the voltage drop of (5.0 Ohms + wire 5 or 6 + wire 4 +
>>> wire 8 plus wire 1) x 2.25 A.
>>>
>>> I do not know how much voltage sag the brake or motor can handle before
>>> they stop working reliably but I would not allow more than 2V drop as
>>> a first estimate.
>>>
>>> The typical "light duty" eight wire rotator cable is 2 x #18, 6 x #22.
>>> DX Engineering says "suitable for most controller to rotator cable
>>> runs of less than 125 feet."  You could probably back out the voltage
>>> drops for a 100' run and use that as a "safe" limit.   The so called
>>> "heavy duty" rotator cable is 2 x 16, 6 x 18 but is probably marginal
>>> at 300 feet.
>>>
>>>
>>> 73,
>>>
>>>    ... Joe, W4TV



Yeah, but you're still looking at 2 strands of 700 ft of AWG10 or AWG8 
to operate the brake. Or, all sorts of gyrations to increase the voltage 
out of the controller (I seem to recall posts some years back looking at 
how high can you make the supply voltage, or using  boost transformers 
on the controller outputs to overcome the losses - sure, if you've got a 
box of 5A 25.2V filament transformers you picked up surplus at a ham 
fest - go for it.)

Viz the cost of wire these days, it would probably be *cheaper* to 
remote the controller to the base.  You could put a Rpi, little relay 
board to control the *stock* controller and a webcam to look at the 
front panel for under $100, although I think a green heron style 
controller might be better in the long run.

If you don't want to do wifi, Fiber optic Media Converters from the 
standard RJ45 network jack run about $40-50 each (you'd need one at each 
end of the run) and the fiber cable would be about $100. So for $200, 
you'd have 100M or 1G ethernet to your tower. (prices are from fs.com - 
a reputable low cost supplier)



500 ft of AWG 10 stranded is $150. You'd need 3 spools so $450. And 
that's just for the first 2 conductors.

You could go aluminum and go a couple gauges bigger and that might 
actually save some money.