Could this be Asbestos fibers (inside a LNB waveguide from a TV satellite dish)? - Page 1
Forum section: electronics / general

author: RoGeorge
author_rank: Super Contributor
timestamp: October 26, 2018, 10:29:21 am
content: There are some fibers stuffing a LNB's opening waveguide. The LNB brand is EchoStar (the black one), probably around 10GHz. There are no labels with the exact model of this EchoStar. It was scrapped from a retired satellite dish of about 1.5 meters diameter.Image 1: The LNB with fibers stuffed in the round Aluminium waveguide is the black one, brand EchoStar. Near it, there is another white LNB from another smaller satellite dish.Image 2: Black case and waveguide removed, the fibers are stuffing the cavity on the right, near the 2 screws. The square entry cavity is 2cm x 1.5cm (about 0.8x0.6 inch)Image 3: Just to see what's inside the LNBImage 4: A closer look inside, with sunlightImage 5: The other side of the inside. Please note there are some white fibers on the inside of the Aluminium flange.Image 6: Fibers on flange, under microscope, magnification x10Image 7: Fibers on flange, under microscope, magnification x30Image 8: Fibers stuffed in the square entry cavity. Microscope x10.Image 9: Fibers stuffed in the square entry cavity. Microscope x30.What material is that? Could it be Asbestos fibers?

author: amyk
author_rank: Super Contributor
timestamp: October 26, 2018, 11:57:57 am
content: It doesn't look like the asbestos I've seen --- it doesn't have the "fluffyness" and curl that white asbestos (the most common type) usually has. You can compare to other photos of asbestos... and of course, try to burn it.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 26, 2018, 12:22:03 pm
content: Thank you. I've already looked at online pics, and couldn't decide what it is, and why are those fibers in there. The radio waves from the dish need to passthroughthe fibers to get inside the LNB.Wouldn't those fibers degrade the 10GHz signal, and being under the open sky, retain water and moisture? Could it be fiberglass then? Maybe something else (online fiberglass pics doesn't doesn't have the tendency to split, as in Image 7)?Puzzling.

author: Ian.M
author_rank: Super Contributor
timestamp: October 26, 2018, 12:33:42 pm
content: The date code on the 74HCT14 is 9245. Echostar is a US company. There is absolutely no way they'd have stuffed loose asbestos fibres into a product in the first half of the 1990's as the hazards of asbestos were well known and legally recognised in the USA from the 1970's onwards.Its extremely improbable that any installer would have access to loose asbestos fibre + decide to stuff a LNB cavity with it.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 26, 2018, 03:23:59 pm
content: Totally makes sense, thank you!

author: Ian.M
author_rank: Super Contributor
timestamp: October 26, 2018, 04:18:50 pm
content: Try grabbing a few fibres with tweezers and try to burn them with a lighter flame. If they burn easily they are some sort of organic fibres, and if they are any sort of glassfibre they'll melt fairly easily in a lighter flame.

author: rhb
author_rank: Super Contributor
timestamp: October 26, 2018, 05:46:43 pm
content: If they are glass, they will appear black if placed between crossed polarizers (e.g. a pair of sunglass lenses).I studied optical mineralogy and happen to have a polarizing microscope. Unfortunately, I don't have a set of immersion fluids which makes an absolute ID more difficult, but if you want to put some in a small envelope taped between two pieces of cardboard (so they don't get broken in the mail) and mail them to me I'll be happy to take a look and see if I can learn anything. If you want me to look at them, PM me and I'll send you my mailing address.As noted, it's extremely unlikely that they are any type of asbestos, which is actually a crystal form which a number of materials take.In any case, the risks of asbestos are greatly exaggerated.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: October 26, 2018, 08:51:25 pm
content: Blue or brown asbestos are bad news, and need careful disposal. White is not a serious problem so long as you don't kick-up dust from it. If in doubt, damp it down before moving it, and double bag it securely.I doubt if this is asbestos anyway.On a similar note, some RF transistors and some magnetrons have a pinkish ceramic washer which contains beryllium oxide. Never break these washers up, because the dust is toxic if inhaled.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 26, 2018, 08:58:43 pm
content: You are too kind,rhb, thank you. To be honest, with all the nowadays emphasis on anti-terrorism and security, I'm afraid to mail unknown materials.Nice tip with the polarized light. I'll search for some polarizers, then give it another look. Maybe I'll try the flame test, too.About the risks of asbestos, as a side story, at the chemistry lab in the 8th grade all the desks were equipped with a Bunsen burner, and on top of the burner, a mesh of metal wires covered in Asbestos.

author: rhb
author_rank: Super Contributor
timestamp: October 26, 2018, 10:37:37 pm
content: I didn't see where you were. It might be a bit of a hassle. I'd be very curious to see what it is. I really think you'd be fine if you labeled it "scientific sample" and added a short cover letter asking for an identification. Particularly if you included some prints of the pictures. I'd be happy to write a good cover letter for you. No assurance I can identify it though. I've not done any optical mineralogy in the 36 years since I got my MS. I spent 9 months looking through a petrographic microscope 8 hours a daylearning the techniques, but never got the chance to do it again. There were no jobs in petrology, so I went into the oil industry. As a consequence, I never acquired the set of references appropriate for doing such work professionally. Just my grad school texts and a few lucky used bookstore finds.A bit of browsing revealed that dielectric fillings are used to adjust the properties of waveguides.If there is a geology department nearby, you might ask the optical mineralogy professor to take a look. Mother nature has a wide range of materials from inert to highly toxic. I've never known a geologist to be particularly concerned about it. You don't eat while handling the stuff and you wash your hands before you eat. Generally speaking one is dealing with very small samples, so getting a significant dose would require consuming the whole sample. If you wander buy with a picture of the waveguide and a tuft of the fibers in a small container any professor worth his salary will at least take a quick look under the microscope. Might not be willing to track it down if it's obscure, but if it's anything common it takes about 10 minutes to do an immersion to get the refractive indices and make a positive ID.Any pair of polarizers which will block all the light when crossed will do. If the material is anisotropic, as you rotate it between crossed polars it will change color. Glass is isotropic, so it won't change colors.

author: Crazy_Pete
author_rank: Regular Contributor
timestamp: October 28, 2018, 02:06:09 am
content: Just an FYI the dangers of asbestos are partially exaggerated and partially underrated. The cancer stats for Asbestos are for the population at large. The truth is that asbestos is a very serious cancer risk for those exposed to tobacco smoke and a very very small risk for those who aren't. What they have done is average the cancer asbestos link for the whole population. This is very misleading because the real risk is for smokers or people who have been exposed to another lung carcinogen. (Miners exposed to Radon gas, for example.) That is if you smoke and are exposed to asbestos your chance of getting lung cancer increase dramatically. If you are exposed to small amounts of asbestos (this doesn't apply to people who are exposed daily like Shipworkers during WWII or Blue Sky Miners) your risk of lung cancer doubles from about 1 in a million to 1 in 500,000.The other thing about asbestos is it is a PHYSICAL carcinogen. That is the physical properties of the crystal are what cause cancer. So there is a great likelihood that similar fibers (for example inhaling glass wool fibres) are an identical risk for cancer. Again it is hard to tell because the risk is only measurable for smokers and they are hell bent on getting cancer anyway. The point of this is that in an electronics lab i think we should use the same rules that i was taught in Chemistry Lab "Guilty until PROVEN otherwise" That is everything is potentially toxic and you should take simple precautions.thankspeter

author: helius
author_rank: Super Contributor
timestamp: October 28, 2018, 02:32:06 am
content: Quote from: Crazy_Pete on October 28, 2018, 02:06:09 amIndeed, even the word "asbestos" is a mineralogical simplification; serpentine and amphibole rocks are very different and don't react the same way in lung tissue.It is similar to misunderstandings around the word "diabetes", as that refers to disorders that produce sweet urine without respect to the cause. "Asbestos" refers to fire-resistant fibers of multiple molecular structures, some of which are much more dangerous.

author: james_s
author_rank: Super Contributor
timestamp: October 28, 2018, 04:13:30 am
content: Asbestos can be dangerous, but it was mostly workers exposed to large amounts of it, people mining asbestos or working in shipyards and other industrial jobs where asbestos is being sawed up and fibers go into the air. The cancer rates are far higher amongst people who both smoke and are exposed to asbestos than either one on its own. Personally I don't worry about it, I still have a few things around that are insulated with asbestos, it's no big deal, just don't eat it or crush it up and inhale the dust.A friend of mine who is involved in construction was telling me that the asbestos removal industry is running out of asbestos to remove and now it's formaldehyde in fiberglass insulation people are being warned about.