Author Topic: snow  (Read 3565 times)

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spacecase0

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snow
« on: December 24, 2015, 07:04:49 PM »
so it snowed here today, and the SWR on my 2M/440 antenna went to heck (it seems to work in the rain ok)
is this a common problem ?
I don't get much snow or ice where I live, so I have no experience...
maybe I should be thinking to setup another antenna type
mine is this one (331KB PDF)
http://www.w5fc.org/files/how-to/j-pole/MENTORFEST_ANTENNA.pdf

also I have to retune my HF antenna when it is wet
but pretty sure that is normal as I have talked to many people with that issue and they have never figured out that it was anything other than the water on the antenna

maybe I should just cover my antenna with plastic (or maybe some neat looking dome) ?

ghrit

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Re: snow
« Reply #1 on: December 24, 2015, 10:21:50 PM »
so it snowed here today, and the SWR on my 2M/440 antenna went to heck (it seems to work in the rain ok)
is this a common problem ?
I don't get much snow or ice where I live, so I have no experience...
maybe I should be thinking to setup another antenna type
mine is this one (331KB PDF)
http://www.w5fc.org/files/how-to/j-pole/MENTORFEST_ANTENNA.pdf

also I have to retune my HF antenna when it is wet
but pretty sure that is normal as I have talked to many people with that issue and they have never figured out that it was anything other than the water on the antenna

maybe I should just cover my antenna with plastic (or maybe some neat looking dome) ?
Perfectly normal.  Anything that changes the conductivity of the antenna, water, ice, snow, dust, bird droppings will make a change in the resonance, hence the SWR.  I'm not sure what effect a different antenna for the vhf/uhf rig would have, but would not be surprised if you find a difference.
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Lamewolf

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Re: snow
« Reply #2 on: December 26, 2015, 12:37:31 PM »


maybe I should just cover my antenna with plastic (or maybe some neat looking dome) ?

I have heard of some folks giving their antenna a good coating of auto wax so the water or snow doesn't stick to it, but I have never tried it to see if it works.  I did read once where a ham had a big wire loop and when the ice built up on it, he would disconnect from the equipment and feed it some DC voltage to heat up the wire and melt the ice off of it.

PS: The Signalink is working well for me and even used it to send a couple of test messages on Winlink !  Also bought a new PC for the shack, the old one was a Win98SE model !

AD

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Re: snow
« Reply #3 on: December 26, 2015, 04:42:00 PM »
Win 98SE? :o

Have you tried running the last free version of Ham Radio Deluxe and run PSK31. Its a lot of fun.
The only dumb question is the one that did not get asked!!

BTPost

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Re: snow
« Reply #4 on: December 26, 2015, 05:05:00 PM »
You might want to look at a Marine Vhf type Antenna that is designed to handle all kinds of WX, AND STILL WORK, CORRECTLY.... I use a Morad 146HD, both in a Regular Gain Whip, and their 10db Base Antenna... These will work correctly even with 10 " of Ice on them.. The Antenna of choice for the North Pacific Fishing Fleet... The 146 is the Ham version of their Marine VHF Antennas. They make an Aicraft Version as well as Uhf, and Cellular Version.. Same basic Design, just cut for the different Frequency Bands. I used the Uhf Version, in my Film Production Company Comms UpGrade Project, for the Base Radio's on each end of the System....  There is a Thread over on SurvivalMonkey.com in the Comms Forum, that documents the whole Project, from Path Survey, to installation, including pictures....
Bruce in alaska AL7AQ

spacecase0

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Re: snow
« Reply #5 on: December 26, 2015, 09:21:15 PM »
I will look into the marine ones that work in all the weather
it was worrying when I could not talk to people at all that I normally talk to on 5W
when I upped the power, the radio shut of its output due to high SWR

maybe if I had been running my 2M amp as it started snowing, it might have stayed warm enough to melt the ice
I do actually have a 2M loop that I could run DC through, but I don't use it.

Tevin

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Re: snow
« Reply #6 on: December 27, 2015, 08:27:39 AM »
Your problem is not normal. A correct antenna should not "go to heck" over light rain and snow. Nor should you need car wax or plastic bags or any gimmicks.

As a general rule, if ordinary precipation screws up an antenna enough that there is a clear & noticeable degradation in performance, then something is really wrong.

I suggest looking for water leakage into the coax where it connects to the antenna. If the coax insulation is chafed through anywhere, that is a point of leakage too. Check traps and coils, and make sure your ground wires are in order.

What I'm basically sayin' is, look everywhere except the antenna itself.


spacecase0

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Re: snow
« Reply #7 on: December 27, 2015, 11:05:10 AM »
I checked the coax, it seems perfect, everything is water tight,
the rain does not mess it up, even frost does not mess it up,
but the snow sure did
not sure if anyone read the antenna design I have, but it is not something that I would have expected to work on 440 in the first place,
I am pretty sure that I need to replace it, I am not ok with this failure...
just have to choose a better design this time

AD

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Re: snow
« Reply #8 on: December 27, 2015, 01:17:36 PM »
« Last Edit: December 27, 2015, 01:23:25 PM by AD »
The only dumb question is the one that did not get asked!!

dangerdan

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Re: snow
« Reply #9 on: December 27, 2015, 05:22:26 PM »
If the coax absorbs water into the dielectric ,the losses will be great .
Any cuts in the jacket ,or at unsealed connectors ,water can enter .

If you do not have an antenna analyzer ,
try a new cable to see if you still have the problem .

73
Dan

Tevin

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Re: snow
« Reply #10 on: December 27, 2015, 06:00:14 PM »
Space

This is my goto UHF/VHF antenna.  Tons of gain, but it is not home built

Good reviews on eham too
http://www.eham.net/reviews/detail/1054

Add me to the list of people who use the X-50 and think it's great. Mine's been out there about seven years now with zero issues. I am in the upper midwest and we get plenty of rain and snow and heavy weather.

The marine antennas that BT suggested are fine, but you should not need to go to such extremes at a land based locale that hardly gets any precipitation. And if the problem really was water/snow on the exterior surface of the antenna, then having a marine antenna will not help because they get wet/iced up just like everything else.

What makes a "marine antennas" a marine antenna is that they are designed to handle the mechanical shock of rockin' and rollin' on a boat, and they may have special coatings/gaskets to protect from salt spray, or special ground considerations...but their guts are just ordinary antennas.

Dangerdan's suggestion to try your antenna with different coax, and if possible a different radio, and see if the trouble clears is spot-on.

And I probably don't have to remind you because I know you're not prone to making rookie mistakes, but always use coax seal. Always.

Since you seem to like making your own antennas, maybe try building an antenna specific to 440. I have a lot of hombrew antennas too (mostly for HF) and not one of them ever give me trouble due to rain, snow, etc. There are plenty of great designs on the interwebs.




 
« Last Edit: December 27, 2015, 06:02:37 PM by Tevin »

spacecase0

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Re: snow
« Reply #11 on: December 27, 2015, 09:45:06 PM »
the coax is dry inside, and everything is watertight,
a dummy load on the end has perfect SWR
if I have to replace the coax, it is beyond my budget...
I know the radio has issues, but they are verified with the SWR meter

and as a side track,
ever connected 2 or more SWR meters in a row ?
anyone that has just one SWR meter knows what is going on, but get 2 or more, and you know that you have no clue what is going on.

I ran out of money 2 years ago,
so either I make new coax our of scrap metal or I don't get it (no tubing here...)
not sure about the loss of making EMT tubing coax, pretty sure EMT tubing is in my price range, but would likely be better off making a green house with any that I managed to obtain

I could go with a 440 antenna only, I already have that, could also easily make a colinear array for one band
but 2M is what really gets out of the area I live in (and my friends are on 440)
annoyingly I only have one spot to put up an antenna
and the current one was selected to have the least wind load of anything as I can't push to hard on the building
any project is tradeoffs, and I don't have any money to trade off

I was pretty sure I knew what was going on before,
and I deeply appreciate the feedback from the outside world
now I am sure of my labor intense, yet no cost path to resolve my issue