Larry Molitor wrote:
>
> Even though the resistors are out in the open, they do not seem to be
> adversely affected by weather. Of course, both in the AZ desert and the
> WA desert, there is no salt spray to worry about.
>
> 73,
>
> Larry - W7IUV
>
If you use traditional carbon composition resistors for their non-
inductive qualities, you are susceptible to moisture absorption. Carbon
comps do suck up moisture readily. As an easy compromise, I do like to
at least encase these resistors in adhesive- wall heat shrink tubing.
The tubing is not that expensive, and you can easily shrink it with
a match or a butane lighter if you don't have a proper heat gun.
Non- desert environments have plenty of moisture in the air to cause
carbon comps to slowly change value, all the more so due to rain.
This will work provided you get a tight seal around the wire. I do
because I usually have a twisted wire connection near the resistor
body which gets soldered. This solder blob is big enough to provide
a seal to the 'recovered' (shrunk) heat shrink and its adhesive.
Another approach would be to use regular tubing that slip- fits
around the resistor body and then semi-encapsulate the ends of the
tubing around the wire leads. Silicone caulk comes to mind here,
but I can think of several other compounds which would work, such as
that tarry, roof patch or tree wound dressing stuff.
73, David K3KY
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