What is the feed arrangement? Gamma, or Delta Match or split driven
element. A balun indicates to me that it is a split driven element (DE)
The insulator for the DE has already been addressed, but if there is a
center insulator, what material is used?
Are all coax connections water proofed? Typically coax doesn't dry out
that quick.
Because of the rapid drying time, this sounds like water on the surface,
or surface layer of an insulator. It could also be a connector. It's
possible for water to get into a connector and not the shield. It most
likely would take warm sunlight to dry a connector, but it could slowly
drain as well. For water and a connector, easy in = easy out,
particularly if the connector is horizontal. A good connector could
prevent water migrating into the coax, yet if not water proofed, could
suffer temporarily from water/moisture inside the connector.
I had an antenna where the SWR went Sky High after a rain, but it stayed
there. I had using 9913 for a feed line and the wind had blown the coax
against the roof, wearing a hole through the jacket, braid, and into the
dielectric which is hollow. There was a junction box (17th photo) on
http://www.rogerhalstead.com/ham_files/boatanch.htm. with a coax splice
just to the left of the photo. The splice (2 PL259 + double female) was
easily pulled into the box. When I unscrewed the coax connector, water
ran out. The 9913 ended at the splice with LMR 400 the rest of the
way. The connector at the antenna was water proofed, but I had not
expected a hole in the coax.
Thus, I would expect water in the coax to not go away within a few hours.
73 es good luck
Roger (K8RI)
On 4/2/2016 Saturday 8:21 AM, StellarCAT wrote:
I’m testing a yagi... I can raise it to ~37’ for testing and lower it to about 8’ for adjustment ... it was made as a duplicate to another one and testing showed it to be just that – a duplicate. Until it rained! The SWR
shifted downward. At 21425 it was ~1.35:1 ... and it would go over 2:1. I’m at a loss as to what is causing this. It is a used antenna reassembled... but I find it very difficult to believe that water could get in to the mechanical joints and
cause this kind of a problem. The balun doesn’t appear to be taking on water – there wasn’t a drain hole in the bottom – there is now – I went out early this morning just after it rained – SWR up high –
and there was nothing coming out of the drain hole. I have checked all connections – they’re tight. Oh – and the strange thing – it goes back to normal after only about 4 – 5 hours without rain. It has done this 3 times
now. It is now – 45 minutes after checking it this morning where it was at 2.33:1, its now down to 1.8:1 and continuing its decent. And further note the SWR seems to be about the same – its just shifted downward when wet. Also I hosed it
down – the balun/coax connection, hairpin for a good 5 minutes – no change. I hosed down the elements at their joints – no change. It rains: changes! The fact that it shifts seems to be independent of height – it does this if
at 37’ or at 8’.
Also: is Noalox the same as penatrox? It is the No AL OX sold by HD ... it says
it is for increased conductivity as well as anti-seize... perhaps IT is the
problem at the joints ... unless someone knows it to be fine (or KNOWS it to be
bad).
thanks – I’m hoping someone has personally seen such a thing and has an idea.
Its holding up the testing of the other antennas.
Gary
ps: the first one had no problems when it was rained on.
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73
Roger (K8RI)
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