Gang,
I'm using a Ubiquiti 30 dBi dish with a 5G30 feed horn that's about 18 months old.. After the recent rainstorms in the Los Angeles area I lost the vertical polarzation.
I tried changing out the two short cables going between the feed and the radio, and separately, the PRISM radio, neither of which was the problem. I finally replaced the feed which did solve the problem. This feed is on my uplink located down on the flats of Glendale and shooting up to Mt. Wilson, so it's tipped up about 4.5 degrees. This dish is shooting to 3 sites on Mt. Wilson and normally providing -40 to -50 dBm signals at the mountain end radios. After the rains the signal levels were down to -60 to -70 dBm at all three radios. Since the problems followed at all three sites I was pretty sure the problem was at my end.
The dish was installed properly with the drain holes facing down, but as I said, from my home location the feed is tipped up about 4.5 degrees. In addition to pulling the little "hoods" down over the RP SMA cables supplied by Ubiquiti, I wrapped the supplied black rubberized tape around the connectors.
When I got the dish down and set it on my bench,face down, I noticed a little bit of water coming out of the drain holes. This pretty much confirmed my suspicion that water had gotten into the feed. I see no sign of damage that might have allowed water to enter the feed.
Now that I've laid that convoluted epistle on you, I'm curious if anyone else has experienced this problem and what you may have done to try to prevent it from happening again? Have any of you ever opened one of these feeds? If so, how did you go about it?
Thanks,
Burt, K6OQK
I'm using a Ubiquiti 30 dBi dish with a 5G30 feed horn that's about 18 months old.. After the recent rainstorms in the Los Angeles area I lost the vertical polarzation.
I tried changing out the two short cables going between the feed and the radio, and separately, the PRISM radio, neither of which was the problem. I finally replaced the feed which did solve the problem. This feed is on my uplink located down on the flats of Glendale and shooting up to Mt. Wilson, so it's tipped up about 4.5 degrees. This dish is shooting to 3 sites on Mt. Wilson and normally providing -40 to -50 dBm signals at the mountain end radios. After the rains the signal levels were down to -60 to -70 dBm at all three radios. Since the problems followed at all three sites I was pretty sure the problem was at my end.
The dish was installed properly with the drain holes facing down, but as I said, from my home location the feed is tipped up about 4.5 degrees. In addition to pulling the little "hoods" down over the RP SMA cables supplied by Ubiquiti, I wrapped the supplied black rubberized tape around the connectors.
When I got the dish down and set it on my bench,face down, I noticed a little bit of water coming out of the drain holes. This pretty much confirmed my suspicion that water had gotten into the feed. I see no sign of damage that might have allowed water to enter the feed.
Now that I've laid that convoluted epistle on you, I'm curious if anyone else has experienced this problem and what you may have done to try to prevent it from happening again? Have any of you ever opened one of these feeds? If so, how did you go about it?
Thanks,
Burt, K6OQK
No specifics on waterproofing them, but I'm happy to report that he two Rockets I have at the Glendale Civic Center (one pointed to Mt. Wilson and the other to Verdugo) seem to have survived all the recent rain. I'm not doing anything special to them.
It's good to hear from you, and yes, it has been quite a while!
It's encouraging to hear that your rockets survived the rains. The three on the mountain have survived with no problems, but as I said, their tipped down.
I use the link from home in Glendale, adjacent to the L.A. Equestrian Center, to Mt. Wilson to control the W6MEP repeater. You can look it up on qrz.com. It's the longest known continuously running automatic repeater, in that it originally went on the air in 1956.
Anyway, I left the feed on my bench overnight with it tipped down at about a 30 degree angle with the drain holes facing down. Not a lot of water came out, but enough to concern me. I'd like to send the feed back to Ubiquiti and have them open it and investigate how this happened. I'd be surprised if I could reach anyone there to talk to or if they would even be interested. Short of that, I will probably attempt to open it myself to see what I can discover. I suspect enough water got into the vertical polarization connector to kill that polarity. I also suspect the associated connections inside may be corroded, although the RP SMA connector looks bright and shiny from the outside. If it wasn't such a pain to get to the dish on my tower and change the feed, I'd like to try it again, but even if it did work, I wouldn't trust it. Maybe a set of drain holes at the connector end might be a worthwhile thing.
The three dishes on the mountain are obviously tipped down, so any water would run towards the drain holes..
Thanks for your comments, and please keep in touch, and if you get a chance, jump on the W6MEP 2-Meter repeater and say hello.
Burt, K6OQK
I opened the feed and found that the the driven elements, are as expected, probes on the SMA connectors. Removing the 6 screws allowed the removal of the driven element housing. My defective feed definitely had water in it that was most likely covering at least the bottom part of the vertical element itself, and even though I let it drain, it still had quite a bit of water droplets in both the driven element housing and the throat of the feed leading to the reflector. There was also a bit of corrosion around the back of the vertical element, but the prob itself was still bright and shiny gold. Since the corrosion was minimal and not over the teflon insulator I was able to easily remove the corrosion and dry out the driven element housing as well as the throat of the feed. I suspect that if I were to put it back together it would work fine.
I intend to reassemble the feed and make sure it has better sealant than provided by the factory. I suspect the radome would help considerably, but i believe the feed itself needs more than just a radome to protect it. There is a rubber gasket that's in a grove (similar to a choke) but the gasket is very thin and I don't see that it has any pressure to make a good seal between the driven element housing and the feed throat. It's just kinda there. Also, the part of the throat where the actual reflector mates with the throat of the feed does not look like it has a good seal. It looks like there's a slight gap in the sealant paint they used.
Since this feed will be used looking up by 4.5 degrees, I'm giving thought to drilling a small hole and the back bottom of the driven element housing part for drainage.
Pictures are available.
Burt, K6OQK