[TowerTalk] TowerTalk Digest, Vol 101, Issue 64

[Robert Chudek - K0RC]

You said: "The center of the pot is connected to the rotor bell housing 
so any resistance between the top and bottom of the rotor will allow 
current to go thru the pot."

If the center of the pot is grounded to the top bell housing, how is the 
potentiometers resistance "seen" across the gap between the top and 
bottom of the rotor housing? Are the ends of the pot connected to the 
bottom housing, putting the pot in parallel with the top and bottom of 
the rotor casing?

I'm trying to understand the failure mode.

73 de Bob - KØRC in MN


On 5/26/2011 2:00 PM, towertalk-request at contesting.com wrote:
> ------------------------------
>
> Message: 3
> Date: Wed, 25 May 2011 22:18:09 -0400
> From: "Gary Schafer"<garyschafer at comcast.net>
> Subject: Re: [TowerTalk] Rotator Question
> To:<k0rc at citlink.net>,	<towertalk at contesting.com>
> Message-ID:<28A8E0D3A500443080D1447CEE36A699 at garyPC>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> Faraday shield with an antenna going into it, the mast.
> There is never a good ground between the mast and the tower as there is a
> rotating joint there. You may be able to measure a short with your ohm meter
> but it is not a good connection to high current lightning. The center of the
> pot is connected to the rotor bell housing so any resistance between the top
> and bottom of the rotor will allow current to go thru the pot. It is a
> common cause of failure.
>
> Bonding the top to the bottom of the rotor is good practice for keeping
> everything on the tower at the same potential when lightning does strike.
>
> 73
> Gary  K4FMX
>
>> >  -----Original Message-----
>> >  From:towertalk-bounces at contesting.com  [mailto:towertalk-
>> >  bounces at contesting.com] On Behalf Of Robert Chudek - K0RC
>> >  Sent: Sunday, May 22, 2011 2:41 PM
>> >  To:towertalk at contesting.com
>> >  Subject: Re: [TowerTalk] Rotator Question
>> >  
>> >  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
>> >  ------------------------------------------------------------------------
>> >  
>> >  On 5/21/2011 2:00 PM,towertalk-request at contesting.com  wrote:
>>> >  >  Message: 2
>>> >  >  Date: Fri, 20 May 2011 15:58:30 -0400
>>> >  >  From: "Gary Schafer"<garyschafer at comcast.net>
>>> >  >  Subject: Re: [TowerTalk] Rotator Question
>>> >  >  To: "'K. Alan Robbins'"<lnmoose at chartermi.net>,
>>> >  >  	<towertalk at contesting.com>
>>> >  >  Message-ID:<30AFC9A2F47C4C3E990DAA8B668AB726 at garyPC>
>>> >  >  Content-Type: text/plain;	charset="us-ascii"
>>> >  >
>>> >  >  You may have had lightning take out the pot. Place a heavy #2-#4
>> >  jumper from
>>> >  >  the top of the rotor to the bottom.
>>> >  >
>>> >  >  73
>>> >  >  Gary  K4FMX
>>> >  >
>>>>> >  >>  >    -----Original Message-----
>>>>> >  >>  >    From:towertalk-bounces at contesting.com   [mailto:towertalk-
>>>>> >  >>  >    bounces at contesting.com] On Behalf Of K. Alan Robbins
>>>>> >  >>  >    Sent: Friday, May 20, 2011 3:08 PM
>>>>> >  >>  >    To:towertalk at contesting.com
>>>>> >  >>  >    Subject: [TowerTalk] Rotator Question
>>>>> >  >>  >
>>>>> >  >>  >    To everyone who responded off-list with gracious help, copies of
>> >  owner's
>>>>> >  >>  >    manuals,  etc.   Thank you very much.
>>>>> >  >>  >
>>>>> >  >>  >
>>>>> >  >>  >
>>>>> >  >>  >    It seems I am the victim of bad luck with this rotator, and/or I
>> >  need
>>>>> >  >>  >    lots
>>>>> >  >>  >    of exercise climbing up and down the tower this year.
>>>>> >  >>  >
>>>>> >  >>  >
>>>>> >  >>  >
>>>>> >  >>  >    73 de W8VCK