[R-390] re: Dangling PTO

[Craig C. Heaton]

Good Morning All,

There are a few reasons to open a PTO, no need to mention those, for me the
big question is the desiccant needed in  civilian usage?

I had to open a Motorola PTO because the desiccant bag broke! This dumped
the desiccant into the rear bearing that supported the drive screw for the
corrector stack and the desiccant even was into the threads of the drive
screw.

Needless to say, the PTO was a little ruff to turn. Anything the desiccant
touched had corrosion, the little spring used to hold tension on the
corrector wiper and roller arm had broken. After cleaning the insides of the
PTO of loose desiccant, lubing the rear bearing and drive screw with a drop
of synthetic 90W, a touch of De-Oxit on the corrector stack and wiper, new
spring installed, the PTO was reassembled without desiccant.

The PTO has worked fine for two years now and the KC knob is smooth as silk.
I'll do my best to keep the R-390A out of running water.

73's
wd8kdg
Craig



-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]On Behalf Of Kenneth G. Gordon
Sent: Sunday, August 20, 2006 7:09 AM
To: Al Parker
Cc: R-390 at mailman.qth.net
Subject: Re: [R-390] re: Dangling PTO


On 19 Aug 2006 at 20:20, Al Parker wrote:

> "WARNING" about breaking the seal, somebody's probably done it anyway,
> and even if not, the desiccant is long past it's usefulness, and I
> haven't been able to reclaim it ever.

Hello again, Al:

I used to work with a seismic outfit that had one of the USGS's World
Wide Seismic Stations in a concrete vault in a canyon in Montana.

Periodically, it would get really wet in there, depending on the time of
year.

We bought several hundred pounds of dessicant surplus, sewed up
some muslin bags to put it in, and spread it around in the vault when we
needed to.

To reactivate it, we simply put it in an industrial oven set somewhat
below the burning point of muslin, I think it was about 200 degrees F, or
maybe a bit more. We would have to ventilate the oven, of course, to
remove the moisture as it was given off by the wet dessicant.

It would generally take at least overnight, but it would always reactivate
just fine.

Why won't the stuff in the PTOs reactivate?

Ken W7EKB
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