[time-nuts] EOL Motorola Oncore Remote Antenna

[Stephen Tompsett]

Breathable vents such as
https://www.hylec-apl.com/venting-elements-breather-plugs
<https://www.hylec-apl.com/venting-elements-breather-plugs> can be useful.

On 30/11/2020 22:08, Lester Veenstra via time-nuts wrote:
> 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.
>
-- 
Stephen Tompsett