OK, I have this problem...

[LeoG]

And I'm pretty sure that it's water in my coax/fittings.  We've been going through a cold spell and the repeater at my shop has been giving full quieting at my house.  Something it's never done since I put it up in the summer.

And the cold spell broke and next thing I know I can barely hear my wife when she tries to contact me.  After a while I noticed a pattern that on above freezing days the signal was bad but when it was below freezing (for hours at least) the signal improved considerably.

So I'm assuming I have water penetration in one of my systems.  I figure it's the shop repeater because I didn't wrap the fitting on the antenna.  It's up there and the only protection was the aluminum tube sleeve that came with the antenna.  Originally thought that would be protection enough but now I'm questioning my (lack of) wisdom.  The house antenna system was wrapped at the antenna and the lightning arrestor.  The shop coax is continuous from the antenna to the repeater.

How can I check to see which of the two is the culprit.  SWR?  Check it when frozen and then check it when thawed?  Any other way to check it besides running new coax to see if the issue disappears?

 

Also, is there a grease (for lack of a better word) that I can fill the fitting with before I make the connection to keep water out?  When I was doing cableless TV installations we had something that I'd put in the fitting to ward off water penetration.  No idea if there is something like that for UHF.  Although it looks like WUTF in Mass is at 500MHz at 970,000 watts which would be UHF and pretty close to 462Mhz that we use.

 

Thanks

[SteveShannon]

36 minutes ago, LeoG said:

And I'm pretty sure that it's water in my coax/fittings.  We've been going through a cold spell and the repeater at my shop has been giving full quieting at my house.  Something it's never done since I put it up in the summer.

And the cold spell broke and next thing I know I can barely hear my wife when she tries to contact me.  After a while I noticed a pattern that on above freezing days the signal was bad but when it was below freezing (for hours at least) the signal improved considerably.

So I'm assuming I have water penetration in one of my systems.  I figure it's the shop repeater because I didn't wrap the fitting on the antenna.  It's up there and the only protection was the aluminum tube sleeve that came with the antenna.  Originally thought that would be protection enough but now I'm questioning my (lack of) wisdom.  The house antenna system was wrapped at the antenna and the lightning arrestor.  The shop coax is continuous from the antenna to the repeater.

How can I check to see which of the two is the culprit.  SWR?  Check it when frozen and then check it when thawed?  Any other way to check it besides running new coax to see if the issue disappears?

 

Also, is there a grease (for lack of a better word) that I can fill the fitting with before I make the connection to keep water out?  When I was doing cableless TV installations we had something that I'd put in the fitting to ward off water penetration.  No idea if there is something like that for UHF.  Although it looks like WUTF in Mass is at 500MHz at 970,000 watts which would be UHF and pretty close to 462Mhz that we use.

 

Thanks

I’m sorry that happened. If it’s one of those aluminum tubes at the bottom of a comet antenna I would have thought the same thing.  As far as grease, some people simply use Vaseline.  Fill the connectors and screw them together.  UHF connectors (plug = PL259, socket = SO239) are not waterproof at all.  Water gets in and ruins the coax.  Depending how long it has been you might have to cut several feet off the end or replace the entire run.  N connectors are sealed much better but should still be sealed in one of several ways.  It sounds like you know exactly what to do, but for anyone reading this who’s wondering, DX Engineering has kits https://www.dxengineering.com/search/part-type/weatherproofing-kits?SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=Coax+Waterproofing+

 

[LeoG]

Vaseline eh?  I'm sure I can find that.  Is there anything that is rated for this use?  The stuff I used came in a tube and I doubt it was as simple as that.  Ya, I know what I did (hangs head).  It's SO239/PL239 for antenna and cable.  The repeater has an N fitting that I had to get an adapter for.  This was only a temp setup that is running long because of my failure when raising my tall mast.  Decided to wait for warm weather to continue, plus work is very busy for me and I don't have time to "play".

[WRYZ926]

You can use dielectric grease. Just put a small amount on the outside of the female threads only.

[LeoG]

This looks appropriate.

 

[LeoG]

10 minutes ago, WRYZ926 said:

You can use dielectric grease. Just put a small amount on the outside of the female threads only.

Stuff I used was put inside the fitting to fill it up so what couldn't get in.

[SteveShannon]

8 minutes ago, LeoG said:

Stuff I used was put inside the fitting to fill it up so what couldn't get in.

That’s how I apply the Vaseline as well.  On a sealed N connector I would not fill it because the sealed fitting might be prevented from fully closing, but for UHF connectors I fill them full and screw them together.

[LeoG]

On an N connector I would likely just fill the internal cup with the dielectric and not the outer diameter where it would be in contact with the threads.

On second thought...  That would keep the water from penetrating in the 1st place.

[LeoG]

OK, brought the SWR meter home last night and it was a bit less than 2.1.  Not good at all.  It was cold enough that I would figure any water in the line was frozen if it was there.  It shouldn't be, the whole system was wrapped with the stretchy tape and then covered with electrical tape.  32º happened at 8pm and I went to bed about midnight and it was still 2.09

This morning it was back to 1.19 and it was pretty cold, 21ºF and colder overnight.  This is my house, not the repeater.  I haven't done any testing on the repeater.

[SteveShannon]

22 hours ago, LeoG said:

On an N connector I would likely just fill the internal cup with the dielectric and not the outer diameter where it would be in contact with the threads.

On second thought...  That would keep the water from penetrating in the 1st place.

An N connector is sealed.  Filling the recess completely with grease could create hydraulic pressure when screwing the connector halves together and that hydraulic pressure could prevent the connector from screwing together fully making the seal even worse.  The video you posted of the “STUF” specifically mentions not to fill an N connector with it, but to use less to avoid this hydraulic pressure.

[SteveShannon]

29 minutes ago, LeoG said:

OK, brought the SWR meter home last night and it was a bit less than 2.1.  Not good at all.  It was cold enough that I would figure any water in the line was frozen if it was there.  It shouldn't be, the whole system was wrapped with the stretchy tape and then covered with electrical tape.  32º happened at 8pm and I went to bed about midnight and it was still 2.09

This morning it was back to 1.19 and it was pretty cold, 21ºF and colder overnight.  This is my house, not the repeater.  I haven't done any testing on the repeater.

I honestly don’t know the effect on SWR of freezing water trapped in coax.  It may be something else entirely that’s causing the rise in SWR. But an SWR of 2.1:1 isn’t really the end of the world.  I’ve operated my ham radio at an SWR exceeding 4:1 before by turning down the power to 30 watts.  I still was very successful at making contacts hundreds of miles away.

[LeoG]

Well I've been having an issue contacting this one repeater I frequent.  I don't have enough evidence gathered yet to say the SWR and the bad reception are a 1 to 1 correlation.  But I plan on leaving the meter inline for a week or so to see if there is a temperature correlation.

Also have issues contacting the repeater at my shop.  Again, just starting up with the investigation into this now that I know my SWR is moving around way more than I think it should.  I understand if it's raining or inclement weather the SWR can move.  But it's been pretty clear.  We had a 1 minute rain event the other day, but the problem has been around way longer than that short rain burst.

[SteveShannon]

21 minutes ago, LeoG said:

Well I've been having an issue contacting this one repeater I frequent.  I don't have enough evidence gathered yet to say the SWR and the bad reception are a 1 to 1 correlation.  But I plan on leaving the meter inline for a week or so to see if there is a temperature correlation.

Also have issues contacting the repeater at my shop.  Again, just starting up with the investigation into this now that I know my SWR is moving around way more than I think it should.  I understand if it's raining or inclement weather the SWR can move.  But it's been pretty clear.  We had a 1 minute rain event the other day, but the problem has been around way longer than that short rain burst.

Certainly water in coax will absolutely mess up impedance, which appears in the SWR.  I wouldn’t argue otherwise, but the water damage is usually permanent and requires that cable be shortened to remove the waterlogged area..  I just don’t know if freezing that water then somehow restores the impedance of the cable. If so, maybe freeze drying a cable would be a possibility to permanently remove the moisture. (Pure irresponsible speculation  on my part!)

I agree SWR shouldn’t change like that and I think you’re smart to watch this and chart the SWR and temperature over time.  I would be interested in knowing if the SWR dip associated with the antenna raises and lowers or moves side to side.  You’d need to sweep it with an analyzer or VNA to see and I don’t know if you have one.  I’m very interested in what you discover.

I’ve had ice build up on a wire antenna before.  The SWR went through the roof. After the ice melted the SWR came back down slightly but I had to shorten the wire to move the dips back where I needed them.

[LeoG]

Ya, no VNA here.  So I'm stuck with the SWR/Power meter to do my investigating.  The other problem is the Holyoke repeater is also having issues currently.  So it's hard to tell if it's me, or them, or both at times.  I have two other repeaters, one nearby (7 miles) and the other farther (17 miles) while the Holyoke is 21 miles.  The other two are always good for contact.

I can hit the Holyoke repeater with my HT and during those periods of me not being able to hit the repeater with my base unit, I can also not hit it with the HT.  So I've always assumed it's atmospheric.  For the entire summer it was full quieting.  Winter came along and now it's a crapshoot.  The whole thing is just frustrating.

[WRYZ926]

SWR can change with temperature changes. I have seen it happen on my HF antennas when temps get into single digits. The SWR usually goes up a bit. But the SWR goes back to normal once temps get to 20 degrees or higher. So far the changes have not been so bad that the internal tuner on my IC-7300 can't handle. Most of the time I don't even need to use the internal tuner.

[LeoG]

I'm getting a much better SWR with cold temps right now.  Still looking at it as I only have one day of information I'm looking at.

[SteveShannon]

35 minutes ago, WRYZ926 said:

SWR can change with temperature changes. I have seen it happen on my HF antennas when temps get into single digits. The SWR usually goes up a bit. But the SWR goes back to normal once temps get to 20 degrees or higher. So far the changes have not been so bad that the internal tuner on my IC-7300 can't handle. Most of the time I don't even need to use the internal tuner.

On an antenna I could see the dip shifting left or right as the length changes with temperature. It would be interesting to chart the dip frequency versus temperature. 

[WRYZ926]

Just now, SteveShannon said:

On an antenna I could see the dip shifting left or right as the length changes with temperature. It would be interesting to chart the dip frequency versus temperature. 

I'll see what I can do to come up with some data. My 6 band cobweb antenna is affected the most when it comes to very cold temps. My thinking is part of the reason is the design. A cobweb is basically a folded fan dipole where all bands (except 6m) are bent into a square.

[LeoG]

And how does this help me ?

 

 

Kidding, kidding.  You kids go out and have fun...

[SteveShannon]

5 minutes ago, LeoG said:

And how does this help me ?

 

 

Kidding, kidding.  You kids go out and have fun...

Maybe it’s related.  Maybe it’s your antenna that’s changing. 
“Kids”. Ha!  my wife reminds me that I'm an old man

[tcp2525]

1 hour ago, LeoG said:

I'm getting a much better SWR with cold temps right now.  Still looking at it as I only have one day of information I'm looking at.

What model antenna are you using? I think that your only solution is to pull the antenna and coax down for a thorough inspection instead of speculating. Either way, the problem is going to need some physical intervention to rectify. 

[LeoG]

Oh ya, I know.  I'll wait until I have access to the bucket truck.  The antenna isn't actually easily accessible.  This is an earlier picture.  The mast holding hardware has been greatly increased.

 

[SteveShannon]

1 hour ago, LeoG said:

I'm getting a much better SWR with cold temps right now.  Still looking at it as I only have one day of information I'm looking at.

What kind of coax are you using?  Specifically, what’s the dielectric made of?  Here’s an interesting article about dielectric changes over temperatures.. 
https://www.microwavejournal.com/articles/27954-minimizing-temperature-induced-phase-errors-in-coaxial-cables

[LeoG]

RG8-X  LOL

No no no.  LMR400 by Times MIcrowave.  Had to see the wife off to NY so I was able to do another check.  2pm 34ºF SWR was 1.25.  I still think the water is frozen in the cable though.

They say to get rid of the water in the cable to use a vacuum with a heated source.  A modern wood Kiln would be perfect.  I was thinking of pulling a vacuum on the outdoor end while heating up the first 3-4 feet of coax to try to rid it of water.  But I'll probably just by 24' of hardline to replace the coax at the house and make it easy on myself.  It doesn't need it.  But it's better suited for outdoors.

[tcp2525]

3 minutes ago, LeoG said:

RG8-X  LOL

No no no.  LMR400 by Times MIcrowave.  Had to see the wife off to NY so I was able to do another check.  2pm 34ºF SWR was 1.25.  I still think the water is frozen in the cable though.

They say to get rid of the water in the cable to use a vacuum with a heated source.  A modern wood Kiln would be perfect.  I was thinking of pulling a vacuum on the outdoor end while heating up the first 3-4 feet of coax to try to rid it of water.  But I'll probably just by 24' of hardline to replace the coax at the house and make it easy on myself.  It doesn't need it.  But it's better suited for outdoors.

Not worth the effort. Toss the antenna if it has an SO-239, and like you said, use hardline with a N connector. Buy an antenna with an N connector and use proper install and weatherproofing techniques and forget about it. Too much wasted energy and time screwing with the stuff you have now.