[time-nuts] EOL Motorola Oncore Remote Antenna

[Lester Veenstra]

This brings up a point I have made frequently, in my professional life.  
Do not try to seal in electronics (for me , satellite units mounted near or
on the feed system) instead warm the area with electronics and place a weep
hole at the low point. Short of true hermetic seals, any other gasketed box
will inhale water vapor, condense it on the cooler surface, and collect
inside as water over time.  Much better to let the enclosure breath a bit
and drain as needed. The hole should not  be subject to external rain
encouraged to come un, and of course, prevent insects from nesting.  Most
active electronics will naturally form a warmer area, discouraging
condensation.

Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y
lester at veenstras.com

452 Stable Ln (HC84 RFD USPS Mail)
Keyser WV 26726

GPS: 39.336826 N  78.982287 W (Google)
GPS: 39.33682 N  78.9823741 W (GPSDO)


Telephones:
Home:                     +1-304-289-6057
US cell                    +1-304-790-9192 
Jamaica cell:           +1-876-456-8898 
 


-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at lists.febo.com] On Behalf Of Art
Sepin
Sent: Monday, November 30, 2020 4:23 PM
To: Poul-Henning Kamp; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna


> To me it looks more like water ingress through micro-cracks in the
>  plastic-dome, and the O-ring did its job and kept that water in.

Interesting. That's the first we've heard about micro-cracks in the Radome
but that's certainly a likely possibility with such a long exposure to U/V.
The more common failure mode reported was moisture ingress due to
"breathing;" the uptake of moisture laden air past the O-Ring, due to a
small pressure differential. But, once the moisture was inside, it was also
trapped internally by the O-Ring. This condition was reported more often in
geographic areas that experienced a wide variation in barometric pressures.


Art

-----Original Message-----
From: Poul-Henning Kamp <phk at phk.freebsd.dk> 
Sent: Sunday, November 29, 2020 11:19 PM
To: Discussion of precise time and frequency measurement
<time-nuts at lists.febo.com>; Art Sepin <art at synergy-gps.com>
Subject: Re: [time-nuts] EOL Motorola Oncore Remote Antenna

--------

> It's obvious from the photo that the O-Ring seal failed its purpose 
> over its many years of service. Has the unit totally failed or does the
electronic portion still function?

No, the electronics is stone dead.

To me it looks more like water ingress through micro-cracks in the
plastic-dome, and the O-ring did its job and kept that water in.

The microcracks are uniform and seem to follow the molding flow, and that is
probably to be expected in our climate:  We have a lot of humid freeze-thaw
cycles.

I wonder if buffing the radomes with car-wax would help ?

> I said lucky because I found some GSynQ parts here in an engineering 
> storage cabinet that we  can send to you at no charge to revive your unit.

Thanks for the offer, but dont bother: I had a spare on hand, and I may
still have third one lying around somewhere.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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