Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
On Mon, 14 May 2012 18:01:01 -0400 Joseph M Gwinn gw...@raytheon.com wrote: Modern outdoor enclosures use a filter of some kind, but the underlying principle is the same. I don't know what other types are around, but we use vents with a gore-tex foil over them. Keeps water out but lets the case breath. This prevents any pressure build up, which would then start to suck watter in from the seal. Unfortunately, i'm currently unable to find the maker or the type of the vent... If anyone is interested in those, i'll can ask around. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
All, W.L.Gore and Associates makes a whole line of these things, but I'm not sure where you go to buy just one. http://www.gore.com/en_xx/products/venting/protective/index.html?xcmp=ijdgpvmktgurl 73, geo - n4ua On Tue, May 15, 2012 at 2:59 AM, Attila Kinali att...@kinali.ch wrote: On Mon, 14 May 2012 18:01:01 -0400 Joseph M Gwinn gw...@raytheon.com wrote: Modern outdoor enclosures use a filter of some kind, but the underlying principle is the same. I don't know what other types are around, but we use vents with a gore-tex foil over them. Keeps water out but lets the case breath. This prevents any pressure build up, which would then start to suck watter in from the seal. Unfortunately, i'm currently unable to find the maker or the type of the vent... If anyone is interested in those, i'll can ask around. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Pretty neat snap in vents and all. Not sure how you buy a few either On Tue, May 15, 2012 at 8:02 AM, George Dubovsky n4ua...@gmail.com wrote: All, W.L.Gore and Associates makes a whole line of these things, but I'm not sure where you go to buy just one. http://www.gore.com/en_xx/products/venting/protective/index.html?xcmp=ijdgpvmktgurl 73, geo - n4ua On Tue, May 15, 2012 at 2:59 AM, Attila Kinali att...@kinali.ch wrote: On Mon, 14 May 2012 18:01:01 -0400 Joseph M Gwinn gw...@raytheon.com wrote: Modern outdoor enclosures use a filter of some kind, but the underlying principle is the same. I don't know what other types are around, but we use vents with a gore-tex foil over them. Keeps water out but lets the case breath. This prevents any pressure build up, which would then start to suck watter in from the seal. Unfortunately, i'm currently unable to find the maker or the type of the vent... If anyone is interested in those, i'll can ask around. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
At 10:49 AM + 5/15/12, time-nuts-requ...@febo.com wrote: Date: Tue, 15 May 2012 08:59:04 +0200 From: Attila Kinali att...@kinali.ch To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water. Message-ID: 20120515085904.19669d7edd8b95454f176...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Mon, 14 May 2012 18:01:01 -0400 Joseph M Gwinn gw...@raytheon.com wrote: Modern outdoor enclosures use a filter of some kind, but the underlying principle is the same. I don't know what other types are around, but we use vents with a gore-tex foil over them. Keeps water out but lets the case breath. This prevents any pressure build up, which would then start to suck water in from the seal. Gore-tex blocks liquid water (and dust), but allows water vapor to pass, so one can still get pumping and the accumulation of condensed water. Where are your enclosures used, and how exposed are they? As for the other methods, so far the following have been discussed: Box with long tube, where the tube volume exceeds the tidal volume of the enclosure, so outside air never manages to get to the enclosure. Typically, the tube is plugged with some cotton wool, to keep insects out. Box with short tube and filter/dessicant. The Gore-tex film is a filter, but not a dessicant. A box with medium tube and filter plus dessicant at the box end can be very effective, the medium tube reducing the rate at which the dessicant is exhausted. Box with short tube that opens on conditioned space. Totally hermetic box. Very effective, but very hard to do in practice, unless the box is small and strong. Box where positive pressure is maintained using dry air, so all leaks are outward and the dew point is never reached inside the box. Joe Gwinn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
On Tue, 15 May 2012 08:35:20 -0400 Joe Gwinn joegw...@comcast.net wrote: Gore-tex blocks liquid water (and dust), but allows water vapor to pass, so one can still get pumping and the accumulation of condensed water. Where are your enclosures used, and how exposed are they? The most exponsed ones... in 3000m height, up in the mountains, free field, nice view in all directions, also weather from all directions... And the occasional lightning strike :-) AFAIK there have not been any defects due to humidy or water accumulation. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Hi Put the box up on a pole where it gets a lot of sun on a regular basis. If it can breathe it will dry it's self out before a lot of water builds up. Simple vent hole in the bottom of the box and don't worry about much elese.. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Joe Gwinn Sent: Tuesday, May 15, 2012 8:35 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water. At 10:49 AM + 5/15/12, time-nuts-requ...@febo.com wrote: Date: Tue, 15 May 2012 08:59:04 +0200 From: Attila Kinali att...@kinali.ch To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water. Message-ID: 20120515085904.19669d7edd8b95454f176...@kinali.ch Content-Type: text/plain; charset=US-ASCII On Mon, 14 May 2012 18:01:01 -0400 Joseph M Gwinn gw...@raytheon.com wrote: Modern outdoor enclosures use a filter of some kind, but the underlying principle is the same. I don't know what other types are around, but we use vents with a gore-tex foil over them. Keeps water out but lets the case breath. This prevents any pressure build up, which would then start to suck water in from the seal. Gore-tex blocks liquid water (and dust), but allows water vapor to pass, so one can still get pumping and the accumulation of condensed water. Where are your enclosures used, and how exposed are they? As for the other methods, so far the following have been discussed: Box with long tube, where the tube volume exceeds the tidal volume of the enclosure, so outside air never manages to get to the enclosure. Typically, the tube is plugged with some cotton wool, to keep insects out. Box with short tube and filter/dessicant. The Gore-tex film is a filter, but not a dessicant. A box with medium tube and filter plus dessicant at the box end can be very effective, the medium tube reducing the rate at which the dessicant is exhausted. Box with short tube that opens on conditioned space. Totally hermetic box. Very effective, but very hard to do in practice, unless the box is small and strong. Box where positive pressure is maintained using dry air, so all leaks are outward and the dew point is never reached inside the box. Joe Gwinn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
This place has them, plus some other stuff that may be of interest to RF types building outdoor devices: http://www.sealingdevices.com/products/gore-vents Unfortunately it looks like you need to ask for a quote, so they may not be open to small orders. Also, McMaster Carr has an assortment of non-Gore breathers using porous bronze or stainless: http://www.mcmaster.com/#breather-vents/=hjnav7 Click on the Breather Vents in the upper left. -John -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of George Dubovsky Sent: Tuesday, May 15, 2012 7:03 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water. All, W.L.Gore and Associates makes a whole line of these things, but I'm not sure where you go to buy just one. http://www.gore.com/en_xx/products/venting/protective/index.html?xcmp=ijdgpvmktgurl 73, geo - n4ua On Tue, May 15, 2012 at 2:59 AM, Attila Kinali att...@kinali.ch wrote: On Mon, 14 May 2012 18:01:01 -0400 Joseph M Gwinn gw...@raytheon.com wrote: Modern outdoor enclosures use a filter of some kind, but the underlying principle is the same. I don't know what other types are around, but we use vents with a gore-tex foil over them. Keeps water out but lets the case breath. This prevents any pressure build up, which would then start to suck watter in from the seal. Unfortunately, i'm currently unable to find the maker or the type of the vent... If anyone is interested in those, i'll can ask around. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Thanks everyone yesterday for your wwvb comment. I now know why the wwvb signal droped to -120db. Seems that over 4 years water slowly built up in the preamp housing. Water and rust do make fine conductors. May have effected bias just a bit and everything else. Washed it all out and will let it dry and take a serious look at whats up. Thanks for the quick replies. Regards Paul ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Paul. On 05/14/2012 07:20 PM, paul swed wrote: Thanks everyone yesterday for your wwvb comment. I now know why the wwvb signal droped to -120db. Seems that over 4 years water slowly built up in the preamp housing. Water and rust do make fine conductors. I had the same problem with a GPS antenna at work. Somebody had put the manufactures label over the porus plug that should have vented out any water... but it didn't so I had too high water-level inside the antenna. Hope you get your amplifier operational again. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Magnus Yes indeed will be working tonight. At least the preamp.Need to figure out what was leaking yet. A bit messy but no real damage and it uses nothing but simple parts. It also allowed water into the coax so will need to chop 3ft off and put a new connector on. Minor stuff. Regards Paul. On Mon, May 14, 2012 at 3:33 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Paul. On 05/14/2012 07:20 PM, paul swed wrote: Thanks everyone yesterday for your wwvb comment. I now know why the wwvb signal droped to -120db. Seems that over 4 years water slowly built up in the preamp housing. Water and rust do make fine conductors. I had the same problem with a GPS antenna at work. Somebody had put the manufactures label over the porus plug that should have vented out any water... but it didn't so I had too high water-level inside the antenna. Hope you get your amplifier operational again. Cheers, Magnus __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Paul, On 05/14/2012 09:46 PM, paul swed wrote: Magnus Yes indeed will be working tonight. At least the preamp.Need to figure out what was leaking yet. A bit messy but no real damage and it uses nothing but simple parts. Good to hear. It also allowed water into the coax so will need to chop 3ft off and put a new connector on. Minor stuff. I was thinking... would adding an additional resistor to add DC load assist in keeping the amp fairly damp-free and also help to keep the cable on the dry side? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
mag...@rubidium.dyndns.org said: I had the same problem with a GPS antenna at work. Somebody had put the manufactures label over the porus plug that should have vented out any water... but it didn't so I had too high water-level inside the antenna. How does water get in? I'm not doubting that it does, just trying to understand the mechanism. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Hal, On 05/14/2012 09:54 PM, Hal Murray wrote: mag...@rubidium.dyndns.org said: I had the same problem with a GPS antenna at work. Somebody had put the manufactures label over the porus plug that should have vented out any water... but it didn't so I had too high water-level inside the antenna. How does water get in? I'm not doubting that it does, just trying to understand the mechanism. There are many ways. No of the joints is perfectly water-blocking, and the plastic itself isn't perfectly water-rejecting. Water will get in there, so you better leak it out. It was the build-up that killed it, not the smaller amounts of water in itself. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
How does water get in? Is this a Spectracom 8206? Should I worry about mine (that one that's outdoors)? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Magnus is right lots of ways for water to sneak in. So I have not had time to figure it out yet. But it is a copper loop and I suspect the place its joining the preamp box let water in over time. The fact is even a small pin hole that allows air in and out thats humid can allow water buildup. But this is a lot and I need to figure out what happened. Its a homebrew antenna but am sure over years even the best can leak. Its about 2ft loop and I had been doing calcs on a 10 ft square loop and such. I suspect that would help quite a bit on the east coast. Time will tell. Still doing a bit of planning and will need to sink some piers for that size of an antenna. Regards Paul. On Mon, May 14, 2012 at 4:11 PM, Jim Hickstein j...@jxh.com wrote: How does water get in? Is this a Spectracom 8206? Should I worry about mine (that one that's outdoors)? __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
On 05/14/2012 11:04 PM, paul swed wrote: Magnus is right lots of ways for water to sneak in. So I have not had time to figure it out yet. But it is a copper loop and I suspect the place its joining the preamp box let water in over time. The fact is even a small pin hole that allows air in and out thats humid can allow water buildup. But this is a lot and I need to figure out what happened. Its a homebrew antenna but am sure over years even the best can leak. Its about 2ft loop and I had been doing calcs on a 10 ft square loop and such. I suspect that would help quite a bit on the east coast. Time will tell. Still doing a bit of planning and will need to sink some piers for that size of an antenna. The antenna which failed was actually quite impressively built. It was well built, but failed in assembly. It's replacement, the same model, have not failed since. One of the things to care about is to not let there be a natural place for water to build up on a joint into the sensitive stuff. If you have a copper loop, then I would turn the tubing upwards into the box rather than on the sides of it, such that water drops of the downside rather than rest on box, and then have some angled ceiling over the box. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
time-nuts-boun...@febo.com wrote on 05/14/2012 05:04:13 PM: From: paul swed paulsw...@gmail.com To: Discussion of precise time and frequency measurement time- n...@febo.com Date: 05/14/2012 05:04 PM Subject: Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water. Sent by: time-nuts-boun...@febo.com Magnus is right lots of ways for water to sneak in. So I have not had time to figure it out yet. But it is a copperloop and I suspect the place it's joining the preamp box lets water in over time. The fact is even a small pin hole that allows air in and out that's humid can allow water buildup. Atmospheric pressure variation, even without wind pressure, is about +/- 10% at the extremes, and it's essentially impossible to make ordinary stuff hermetic enough to prevent breathing. The classic dodge is to connect a long tube to the enclosure, with the tube having sufficient volume that the breathing is restricted to the tube. Or, have the tube connect to a conditioned space, like the house. Then, the inevitable small leaks no longer matter as the tube equalizes the pressure. The extreme example of isolation using a tube is Pasteur's swan neck flask. http://en.wikipedia.org/wiki/Louis_Pasteur Modern outdoor enclosures use a filter of some kind, but the underlying principle is the same. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wwvb weak on east coast especially when the pre-amps under water.
Am 14.05.2012 21:54, schrieb Hal Murray: mag...@rubidium.dyndns.org said: I had the same problem with a GPS antenna at work. Somebody had put the manufactures label over the porus plug that should have vented out any water... but it didn't so I had too high water-level inside the antenna. How does water get in? I'm not doubting that it does, just trying to understand the mechanism. Let me try to explain it. The mechanism is as follows: Air does contain water in form of gas (vapour) which does condense to water when the temperature drops down (eg. at night). The problem is coming up on tight boxes having a pressure leak eg. due to defective sealing, cracks or via non hermetic cable connections. Changing air pressure do always pump in fresh and humid air and the condensed water remain on the bottom inside the box and may as well penetrate into the wire mesh/ braid of coaxial cables. The copper will start modering and turn black. The only solutions I think: Apply air pressure tight boxes having a breathing hole an the bottom, mount the box that no rain and water can penetrate from the top or sides. If the hole is big enough, eg. 2mm, no pressure difference is possible and no pumping effect will occur. (If the hole is too wide, small animals may penetrate). Or, when using a pressure tight box, it must be stiff and sealed to withstand under all temperature conditions more then 1 bar/ 100 kPa. Do not forget that all feed throughs must be of real hermetic type, normal coaxial connectors are not tight! Don't route cables directly in, because no cable braid or mesh is vapor tight. I hope this will help, we had never problems that way. Arnold ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
