[Milsurplus] Water, Water Everywhere.

[Bob Camp]

Hi

Before you start, consider that there may be a layer of dirt involved in the process. 
The time to get rid of that is *before* the dry out. The usual cautions apply to using
solvents to do this. 

Winter is a good time to do a dry out process. All you really need to do is 
get the humidity down low and keep it there for quite a while. You can accelerate
things with a lot of heat. That may or may not damage other stuff in the gear. More
or less:

Rig a hot box, heat it with what ever you have
Monitor the temperature with something simple 
Keep some air flowing inside the box with a small fan
Control the air exchange with the outside so there is *some* exchange
For added fun monitor the humidity. (or look at the humidity outdoors and 
do the delta T math). 

The goal would be 0% RH (which is impossible). Anything below 5% is likely to be 
“good enough"

Once you get the humidity out, you need to keep it from getting back in. The issue
is that whatever was doing that probably has degraded in the last 50 to 100 years (haven’t we 
all …). There are an enormous number of candidates for this. Many of them can create
as much trouble as they fix. For solid parts, low viscosity / long setting time epoxy
might be your best bet. For delicate little stuff, something like silicon (synthetic) oil 
may be about the only viable approach. As always, proceed carefully. You very much
do *not* want to toss this stuff in there and find it dissolves the part(s). There have been
so many materials used over the years that there is no 100% safe thing to use. If oil 
and epoxy are out, then stuff like wax is your next choice. In a hot part of a radio, they may not
do really well. In a room temperature part of the gear, they work quite well. 

It’s also quite acceptable to skip the displacement step. You may find that your dry out 
process needs to be repeated in a few years.

Bob


> On Dec 11, 2015, at 11:43 AM, David Stinson <arc5 at ix.netcom.com> wrote:
> 
> Many of our beloved old radios have been sitting, cold
> and quiet for many decades.  Some of them getting close to a century.
> Recently, I've been dealing with bakelite and phenolic
> in our sets which have taken-up moisture over the years.  Right now on the bench I have a TCS
> receiver in which one of the pins of Z202, an IF transformer, is leaking B+ to ground through
> the phenolic.  Pulling an IF from a TCS is a pain
> but do-able.  So may we discuss ways to gently drive moisture
> from our sets?  I can "get rough" in the stove with
> those bakelite inserts in WWII radio connectors but
> that won't do for a whole set.  I've tried powering just the filaments and leaving a set for a couple of days but I don't think they get hot enough to do much
> good.  Heat lamps can do some damage.
> What have you done?    I'm thinking of light bulbs
> with the radio in a thick cardboard box, *outside* in case the box decides to catch fire or something.
> 
> 73 Dave AB5S
> 
> 
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