[TowerTalk] Water in matching sections

[Clive Penna]

Hi ,  You could also add a few bags of Silica Gel Desiccant in the box
to absorb any unwanted moisture. 73 Clive GM3POI
-----Original Message-----
From: alsopb <alsopb@gloryroad.net>
To: Towertalk@contesting.com <Towertalk@contesting.com>
Date: 18 December 1998 14:37
Subject: [TowerTalk] Water in matching sections


>
>Guys,
>
>I finally unraveled a mystery that has plagued me for almost two years.
>
>Every winter the SWR on my 160 meter inverted L would go crazy after a
>hard freeze. The symptom -- low power SWR a bit high but it climbed a
>lot when high power used. The first thought -- water in the coax
>somewhere.  After many tries at trouble shooting with an RF analyzer,
>replacing sections of coax, redoing connectors, a permanent fix was not
>found.  Of course, the problem went away if the temperature got
>significantly above freezing....  
>
>Today I found it (I think).  In the L-network matching section I have
>there is a 350mmfd variable capacitor mounted vertically.  Although the
>box is watertight, there were water droplets between several sections.
>Blowing it away caused the problem to go away!  It appears that frost
>forms on the plates, melts and forms droplets.  I guess the solution
>will be to mount the cap horizontally so that the water will drain or
>replace it with a fixed value cap.
>
>Who would have thought.....
>
>73 de Brian/K3KO
>
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>


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