How is enough RF voltage (hundreds of volts) built up across the
lubricant between the ball bearings and the race above/below?
Both the top and the bottom of the rotor casing are at ground potential.
The base sites on the grounded rotor base. The mast is grounded as it
leaves the top of the tower section.
73 de Bob - KØRC in MN
------------------------------------------------------------------------
On 5/23/2011 1:15 PM, towertalk-request@contesting.com wrote:
> Message: 3
> Date: Mon, 23 May 2011 08:02:27 -0700
> From: Grant Saviers<grants2@pacbell.net>
> Subject: Re: [TowerTalk] Rotator Question
> To: pfizenmayer<pfizenmayer2@q.com>
> Cc:towertalk@contesting.com
> Message-ID:<4DDA7703.8010905@pacbell.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> The TVI was most likely an arc or spark when the voltage exceeded the
> breakdown voltage of the oil film in the bearing. race - oil -ball -oil
> - race. So the rotator halves are insulated from each other by the oil film.
>
> Electrical Discharge Machining (EDM) machines by spark eroding metal.
> That is what is happening to your rotator races and bearing balls. The
> oil/grease also degrades from the arc burning through the oil film.
>
> It doesn't take much of a wire to drain static charge or short out RF
> potential around a bearing. My choice would be 12 to 16ga stranded for
> ease of finding large ring terminals, mechanical durability,
> flexibility, and dressing it for rotation.
>
> Of course a 12ga wire will be worthless if it is the primary conduction
> path for a direct lightning hit.
>
> Grant KZ1W
>
> On 5/22/2011 11:44 PM, pfizenmayer wrote:
>> >
>>> >> FWIW, I had to put a wire across my rotor because RF currents
>>> >> going though the bearings caused TVI.
>>> >> Rick N6RK
>> > On 5/22/2011 11:41 AM, Robert Chudek - K0RC wrote:
>>> >> Please tell me what this #2-#4 wire is going to do that the Faraday
>>> >> shield effect of the tower legs around the rotor is not going to do? Or
>>> >> the metal of the rotor bell-housing itself? That pot is buried several
>>> >> layers deep, covered with metal. Does a #2-#4 wire have some priority
>>> >> for lightning? I really need to know, as I have been extremely lucky to
>>> >> escape any rotor damage, even with several lightning direct hits to my
>>> >> tower.
>>> >>
>>> >> 73 de Bob - K?RC in MN
>> > and on 160 I got all kinds of BC IMOD until I tied across top and bottom
>> > .
>> >
>> > Hank K7HP
>> >
>> > _______________________________________________
>> >
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