[NLRS] loop yagi driven element corrosion

Thu Sep 15 12:02:38 EDT 2016

There is a product made by Rustoleum called Never-Wet. It is a two-part
spray - a primer coat followed by the water repellent coat. They recommend
not using it on electronics but I think that's meant for pc boards and
such. It works on dish surfaces - water and ice just fall right off. It
might be good to treat the looper driven element with it. I haven't had
such problems because I use my loopers portable and store them in the
garage when I'm not using them.

All hardware stores around here sell the Never-Wet. I think it's easy to
come by.

73, Zack W9SZ

On Thu, Sep 15, 2016 at 10:51 AM, Dr. Gerald N. Johnson <geraldj at netins.net>
wrote:

>
>
> Some European authors about antennas have advocated covering the entire
> antenna with an epoxy paint for weather protection. There is a chance the
> dielectric of the coating could change the antenna performance by adding
> losses and changing the resonant frequencies of the elements.
>
> In constructing the looper it would be nicest of the directors could be
> cut from extruded tubing to have no joints, but that would be difficult to
> get the right dimensions without starting with heavy wall tubing and a
> metal lathe and converting most of the aluminum to scrap shavings. I would
> stick with the single end holes on the director (and reflector) loops but
> would put a drop of Alnox electricians aluminum wire connection grease
> (filled with zinc crystals that break through aluminum oxide to get to the
> bare metal) and I'd put a nut against the loop to squeeze that grease
> tightly not depending on the stiffness of the boom for that contact
> pressure. I'd be temped to insert a stainless steel internal or external
> shake proof lock washer too that will bite through the aluminum oxide that
> is always present. I've run aluminum jacketed CATV coax for decades outside
> with Alnox at my home made connector adapters covered with Scotch #33 or 88
> and not detected any changes.
>
> I'm sure the latest International Microwave Handbook has several pages on
> building loopers which should include the knowledge of old timers. It
> suggests making welded directors of stainless steel welding wire, same for
> the driven element using acid core solder to get the ends tinned. Then
> coating the driven element, solder connections, and screws with
> polyurethane varnish, and finally paint the entire antenna. Mostly on page
> 57 in the antenna chapter. The paint type isn't specified.
>
> I have a direction systems looper in the basement but would rather not
> open the packaging to read their instructions.
>
> 73, Jerry, K0CQ
>
>
>
> On 9/15/2016 8:33 AM, Chris Elmquist wrote:
>
>>
>>
>> OK. Thanks again guys.  I have received a couple other replies that
>> suggest
>> this discoloration is happening elsewhere too and so that is a data point
>> I was looking for.   That's the good news/bad news piece that says it's
>> probably not some dissimilar metal action or magical mystery currents
>> eating away my loopers and just the elements doing their thing on the
>> elements ;-)
>>
>> Am making plans to overhaul the whole setup here next year so will just
>> leave them alone until then and hope that Santa brings me a new tower
>> this Christmas and then I can clean them up and move them a lot higher
>> in the air where they really belong.
>>
>> 73, Chris N0JCF
>>
>> On Thursday (09/15/2016 at 06:34AM -0500), Ray Johnson wrote:
>>
>>>
>>>
>>> Hi All
>>>
>>> In a later RSGB publication, Radcom I think, it was suggested that
>>> the original design was not the best for long term reliability.
>>>
>>> The claim was that the bottom of the loop is a high current point
>>> and having an overlapping  joint there is bad for the long term.
>>>
>>> The revised design would rotate the overlap point by 90 degrees and
>>> require 2 fasteners for each element: A long fastener to hold the
>>> element to the mast and then a short fastener to handle the overlap
>>> point. The claim is that this improves the reliability.
>>>
>>> I am sorry I don't exactly remember where I read this.  A friend
>>> gave me some 20+ years of Radcom back issues and it would take a
>>> while to find that article
>>>
>>> Worth the extra effort when you build a looper ?..........I will
>>> leave that discussion to the pontification crowd......
>>>
>>> rayj  WB0EBG
>>>
>>>
>>> On 9/14/2016 11:19 PM, Dr. Gerald N. Johnson wrote:
>>>
>>>>
>>>>
>>>> In VHF Communications for 1/1978 an article on loop yagies
>>>> suggested the driven element and feed along with the screws be
>>>> coated with polyurethane lacquer and when it dried, the entire
>>>> antenna be coated with ordinary lacquer. Somewhere I have a
>>>> vintage RSGB microwave publication with a chapter on loop yagis,
>>>> but I haven't turned it up in my first search this evening.
>>>>
>>>> 73, Jerry, K0CQ
>>>>
>>>> On 9/14/2016 9:40 PM, Chris Elmquist wrote:
>>>>
>>>>
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>>
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