I had a thunderstorm the other day and later found that my PiAware was picking up almost no traffic. I have an outside antenna and a lighting arrestor. After some troubleshooting, I had put my unit back in the attic with the small antenna that comes with the receiver. That has me working in a limited basis. My question is: What is fried, the antenna, arrestor, or both? It’s a pain to get up there, so I would like to do it only once if possible. I measure about 80K Ohms for the cable and antenna, but I have no idea what this should be.
Thanks,
Pat
Between what two points?
If there’s no visible damage and the receiver is OK with a different antenna then a more likely explanation is water ingress.
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Thanks. The 80K is the cable (about 40’ LMR-400), lightning arrestor and antenna.
Should I put some dielectric grease in the connections?
Still not sure what two points you are measuring. The resistance between the center pin at the receiver end and the center pin of the far end of your cable should be close to zero, not 80k. Resistance between center pin and shield isn’t particularly useful to measure.
Neither the antenna nor the feeder will have been damaged by a ‘local’ lightening strike.
Of the options provided, that leaves the arrestor, but I’d agree that water in the coax could explain a lot.
What type of outdoor antenna do you have? and what kind of connectors have you used? (pics?)
80 kohm points to moisture in the cable.
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I have the FightAware 1090 Mhz 26" outside antenna with N Connectors. I’ve been reading up on sealing the Coax connections. It will be done differently the next time.
Is the water typically in the connector only, or does it get in the cable itself?
N connectors are usually reasonably weather resistant - they have a seal that should help keep water out, but it’s not always completely effective. If water does get into the connector, it’s possible for it to wick up the coax depending on its construction. It’s a good idea to put some silicone or dielectric grease in external connectors - it keeps water out and inhibits corrosion.
There was a thread on here some time back where someone had got water ingress to the antenna tube, so that’s also possibility.
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Thanks for all of the responses! I have to borrow a 12’ ladder to get up there, so it will be next week, but I have an idea of what to look for.
Pat
I just wrapped the connector with self fusing 3M tape and on top of that I put regular UV resistant electrical tape.
Also on your picture you are missing the conductor to the ground rod. You don’t want an eventual lightning strike to come inside the house, do you?
I have the same FA antenna and had lots of water intrusion into the N connector at the base of the antenna. I cleaned it out with some rubbing alcohol and compressed air. After that the feed went back to normal.
A kind user on here recommend this tape.
https://www.amazon.com/gp/product/B00K5GW67O/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1
Since adding this tape I’ve had no further issues with water.
As a follow up, I pulled the antenna down last week and found water in the connectors. I also found that the lightning arrestor was shorting out. I dried everything out and used Self-Fusing weather proof tape with 3M 88+ tape on top of that. While I was at it, I added 10’ to the mast and I’m picking up traffic from about 50 more miles.
Thanks to all the help.
Pat
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Here’s my FlightAware antenna after 8months.
The glue bonding the antenna into the mount shrunk which help water get through to the connector, so you might want to seal that as well with some UV silicone(or silicone tape).
Macro
You can see the residue from the draining on the last one.
My self fusing tape held up on the connector okay, so I didn’t get water in the cable.
Thinking about it, I would probably unscrew the pole mount bracket, and move it up a bit higher, so there was better wrapping space above the N connector.
Not knowing the internal antenna layout though, that might negatively effect reception.
The nuts could use replacing too as they aren’t Stainless Steel it seems.
I switched to DPD 1090 while I had the Flightware antenna down for maintenance, and never put it back(or fixed it up).
I plan to clean it up and mount it on another mast for my backup and testing at some point.
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mine did exactly the same. i have to put the self fusing tape and 3M tape on top of the area shown in the above photos to prevent water/moisture from getting into the N type connector as well
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