[TowerTalk] Smoking control box or-2800dc semi conclusion...

[David Robbins]

sounds like a poor practice to me, especially for long cables that may be exposed to lightning directly or nearby.  The problem is that at the end where the ground is disconnected there is no way to equalize the voltage between the other conductors and the ground.  This could cause extremely high voltages at that point causing flashovers in the cable.  

'ground loops' should really be fixed by other methods, like fixing the equipment that doesn't have a proper ground in it, rather than by allowing different ground potentials to exist.

Jun 5, 2012 08:36:02 AM, n1bnc at yahoo.com wrote:

Here is the rational:

That ground wire is used
as a drain, and unlike in RF cables, it is good practice to only tie 
one end of a drain to ground to prevent
the possibility of a ground loop.

Nat Lee

Somersworth, NH

--- On Mon, 6/4/12, Dick Williams wrote:

From: Dick Williams 
Subject: Re: [TowerTalk] Smoking control box or-2800dc semi conclusion...
To: towertalk at contesting.com
Date: Monday, June 4, 2012, 7:37 PM

Nat,

To tell you the truth, I have never heard that;  of course that "begs the
question" as to why the "ground" screw is on the control box and the rotor
connector if you are not suppose to use it.  Additionally, if it was a "big
deal", why would the installation instructions not mention that and inform
one on how to do it correctly?

The only "non-standard" rotor hook up that I know of (that is not published
anywhere that I know of) concerns Ham Ms and Tailtwisters.  The "change"
involves mounting the motor run capacitor in a box by the rotor, and not use
the one in the control box. There are two advantages to doing this; first,
the capacitor is right by the motor (where it should be for best
efficiency).  And second, that "frees up" the two wires going to the
capacitor in the rotor box to now be paralleled with the motor run wires;
that results in less voltage drop at the motor, and better efficiency.

In any case, it will be interesting to hear what the rational is concerning
the ground wire.

Dick  K8ZTT

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Nathaniel Lee
Sent: Monday, June 04, 2012 4:31 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Smoking control box or-2800dc semi conclusion...

Hi All.

Today the rotor and control box were both swapped out and everything is
behaving as expected. The were no defects in wiring inside the little box at
the rotor. So something internal must have died. I am awaiting clinical
results from M2. M2 really came out ahead in the customer service
department. Kudos!

One thing mentioned by the installer that was of interest was to not use the
ground connection in the rotor cable. Anyone else familiar with this?

Thanks for the bandwidth.

Nat Lee

Somersworth, NH
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