non-existent reception while raining after new dish/LNB install

[lost_one]

I installed/aligned new dish 85cm Gibertini and Inverto Unicable II LNB on Friday. The TV reception and the SNR values (minimum 87%/max 99%) on the built-in OpenVIX image were excellent for about 24 hours.

On Saturday evening we had a moderate rain, after about 5 minutes I got "tune failed" on screen and all of the SNR values were zero%. about an hour after the rain stopped, the TV reception and SNR values returned to what they were before the rain started.

It is sunny and clear in my location today, and the TV reception is excellent, and SNR values are all minimum 85%.

This is my first dish install/alignment, but I think it is most likely water ingress into one of the connections but I'm not sure. I would think if it was an alignment problem, the SNR values would decrease, but not go all the way to zero. What do you think?

I unscrewed the connector from the LNB this morning and applied silicone grease to the LNB threads and installed a rubber o-ring in the plug to try and prevent water from getting in there. Is this the best thing to do?

I noticed something that is kind of strange to me; the Inverto IDLU-32UL40-UNBOO-OPP that I have like here: https://www.dipolnet.com/unicable_ii_lnb_inverto_idlu-32ul40-unboo-opp_-nc_-_A98224.htm.

The top of the LNB plastic casing has holes in it, I can't imagine this being a design flaw from a company like Inverto?? Also, if it was a known problem, I would think there would be complaints all over the internet, and I haven't seen any.

Thanks for your help.

[twol]

I installed/aligned new dish 85cm Gibertini and Inverto Unicable II LNB on Friday. The TV reception and the SNR values (minimum 87%/max 99%) on the built-in OpenVIX image were excellent for about 24 hours.

On Saturday evening we had a moderate rain, after about 5 minutes I got "tune failed" on screen and all of the SNR values were zero%. about an hour after the rain stopped, the TV reception and SNR values returned to what they were before the rain started.

It is sunny and clear in my location today, and the TV reception is excellent, and SNR values are all minimum 85%.

This is my first dish install/alignment, but I think it is most likely water ingress into one of the connections but I'm not sure. I would think if it was an alignment problem, the SNR values would decrease, but not go all the way to zero. What do you think?

I unscrewed the connector from the LNB this morning and applied silicone grease to the LNB threads and installed a rubber o-ring in the plug to try and prevent water from getting in there. Is this the best thing to do?

I noticed something that is kind of strange to me; the Inverto IDLU-32UL40-UNBOO-OPP that I have like here: https://www.dipolnet.com/unicable_ii_lnb_inverto_idlu-32ul40-unboo-opp_-nc_-_A98224.htm.

The top of the LNB plastic casing has holes in it, I can't imagine this being a design flaw from a company like Inverto?? Also, if it was a known problem, I would think there would be complaints all over the internet, and I haven't seen any.

Thanks for your help.
Heavy rain/snow etc I get 0 values on 28.2E and even 27.5W. Don't think that has ever happened to 19.2E but then again, I could probably pick up 19.2E with a shirt hanger

[ronand]

Silicone grease is not conductive and shouldn't be used in such situations. The supplied rubber cover should be enough to keep water out of the connector.

[adm]

Silicone grease is not conductive and shouldn't be used in such situations. The supplied rubber cover should be enough to keep water out of the connector.

The grease does not form an insulated connection - the pin of the F plug will still have a mating metal to metal electrical connection with the socket on the LNB, the screen will always have a metal to metal contact via the screw thread.

Some rubber boots are good but not all.


http://www.wrightsaerials.tv/roguesgallery/183.shtml#img2


Self amalgamating tape is good for waterproofing connections. The (outside) of the connectors have to be oil/grease free before wrapping in self amalgamating tape. To apply the tape remove the backing and stretch the tape to 2x to 5x its length whilst wrapping. Note: stretching whilst wrapping is important.


http://www.satcure.co.uk/tech/self_amalg.htm
https://www.youtube.com/watch?v=4uJNlWFDZt0

[ronand]

The grease does not form an insulated connection - the pin of the F plug will still have a mating metal to metal electrical connection with the socket on the LNB, the screen will always have a metal to metal contact via the screw thread.

The OP said he put the grease on the threads. Not electrically good.

[Joe_90]

The OP said he put the grease on the threads. Not electrically good.

Silicone grease is absolutely fine on the threads and keeps water and corrosion at bay. The metal to metal connection on the centre conductor and the threads to the braid displace the grease at those points. The guy who ran Sat-Cure (dish installer/supplier) was a great advocate for silicone grease. @adm is absolutely correct as regards the self-amalgamating tape. You need to ensure the external surfaces of the F-plugs are free from grease before stretching and wrapping the tape. The last time I replaced my motorised dish, the F-plug was as clean as when I had installed it about ten years previously, once I cut off the amalgamating tape.

[ronand]

I'll agree with the self-amalgamating tape - I use it all the time on ham antennas. Although it looks a little fiddly to get on that lnb as the connector seems recessed.

[BrokenUnusableAccount]

My thoughts:

You can't necessarily assume that the S/N figures are any more than somewhat vague approximations.
Typically, if the tuner cannot lock on to the signal, it cannot give you any S/N figure.
In my experience, it's normally somewhere in the region of 6dB S/N (plus or minus 1 to 2 dB) that the transition from "just about usable" to "unable to lock" occurs.

An hour seems a little quick for water ingress to clear all on its own, but I guess it is possible.

Rain does affect satellite reception, it attenuates the signal.
Remember that in the UK satellite dishes are aimed at quite a low angle so heavy rain some distance away can cause loss of reception, it doesn't necessarily have to be raining on you.

[nekrub2]

Rain drops on the LNB head pointing to the dish has a substantial impact on the SNR level. In my case on hotbird 13E I get 94% on dry days, during a heavy rainstorm it can drop to 45%.
For a while I had a self-built umbrella over the LNBs but it did not hold for long in the storm.

[lost_one]

Thanks for all the help and inputs for my situation.

I purchased on of these:https://www.amazon.co.uk/Hd-line-LNB-weather-protection-cover-WetterSchutzhaube/dp/B07NNTNC2T and it seems to be fine, although we have only had moderate rainstorms since I've put the dish up. After installing this "protector", my SNR values dropped about 8 - 10% in the rain, without the protector, they decreased to "zero" in the rain.

My old setup of a Sky minidish (not sure about zones), looks about 60cm, with Sky OEM LNB would get bad reception during light/moderate rain, but SNR values never decreased to zero, usually about 30 - 40% in moderate/heavy rain. The picture, as expected, was pixelated, and often "tune failed".

In clear/sunny weather, I would get a max of 70% SNR, so maybe original LNB/dish alignment, or both were culprit?

Most people say if you get bad reception during rain/bad weather; get a bigger dish, so I got an 85cm dish. The SNR values are a solid 90 - even 100% on ITV SD channels with the new 85cm dish in clear skies, so that it is a technical improvement. However, I think it might have been a waste of time and money for me, as without the "rain protector", the reception during bad weather has not improved, and maybe even gotten worse.

I have no experience with dish installation/alignment, but the technician in me finds it hard to believe that the dish alignment is causing bad reception ONLY during bad weather...is this a bad assumption?

Thanks