[NLRS] [BC'ers] Coax to antenna feedpoints: an unbroken run or a rotor loop transition connection?

[Dr. Gerald N. Johnson]

The ARRL's book on Towers has a chapter on weather proofing connectors. 
Scotch 33 is central, 88 is good too. Multiple layers alternating either 
tape and Schotchkote liquid is good when the liquid can be found. Its 
getting uncommon. Liquid tape can be had a lot easier and should be good 
too. Stretch the tape a lot to take care of different diameters, but cut 
the end and don't stretch the last couple turns. Don't break the tape 
from the roll by stretching it, it will peel back in time. Imitations of 
the real Scotch tape product generally don't work nearly as well.

Antenna feed connectors need waterproofing on both sides, the coax and 
the antenna feed details. Ordinary chassis mount connectors generally 
used for that are NOT water tight and let water get into the coax. Hot 
melt glue or liquid tape should work there. Also sprayed layers of clear 
Krylon or Rustoleum should be good too. A C3I 432 yagi kit I assembled 
last month recommended the clear Krylon.

73. Jerry, K0CQ

On 8/27/2015 8:43 PM, Scott Neader KA9FOX wrote:
> I'm far from an expert, but I did have one install my stuff (Rev. Paul
> W0AIH).  He ran coax to the top of the tower, then put a connector and
> barrel at the top, then transitioned to a piece of coax referred to as the
> "rotor loop"
>
> Keep in mind that many of my cables (and hopefully yours) are of low loss,
> hardline type.  You can't possibly run hardline as your rotor loop, so you
> will need to transition anyway.  Having ALL of them transitioned this way
> does allow for easier servicing, as you suggested.
>
> Also, even if you aren't using hardline, you still need special "flexible"
> cable for your rotor loop. You don't want or need that for the whole run,
> just the rotor loop at the top.  There are some good low-loss cable for
> this purpose, from LMR and others.
>
> Lastly, while this may not be ideal, I have no such "junction box" at the
> top and I've never seen anyone do that.  Just use a barrel connector or
> whatever you need to join the pieces of coax... use lots of waterproofing
> (elephant snot, rubber sheets or whatever your preference is) and then tape
> that up good with Scotch 33, etc.  Your junction box will probably just
> fill with water anyway. :-)
>
> - Scott KA9FOX
>
> On Thu, Aug 27, 2015 at 11:19 AM, David Palm<thepalmhq at gmail.com>  wrote:
>
>> I have new antennas to put up for 50/144/222/432.  I may have time to get
>> them up before the September contest.
>>
>> My question is whether most of you run an unbroken cable all the way from
>> your lightning arrestors to the feedpoint of the antennas (with enough
>> extra at the top to create a rotor loop), or whether you do a run from the
>> arrestors to a junction box at the top of the tower, then transition to
>> shorter rotor loop sections to the feedpoints?  It's an additional hassle
>> and some loss involved in the second scenario, but now I'm thinking that in
>> terms of being able to service individual antennas it would be nice to be
>> able to disconnect them at the top of the tower and have only a relatively
>> few feet of cable to wrangle with.
>>
>> Your thoughts would be helpful, as this will all be happening quite soon.
>>
>> 73,
>>
>> David  W9HQ
>> ______________________________________________________________
>> BadgerContesters mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/badgercontesters
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:BadgerContesters at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> BadgerContesters mailing list
> Home: http://mailman.qth.net/mailman/listinfo/badgercontesters
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:BadgerContesters at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>