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Carbon Brush

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Posts posted by Carbon Brush

  1. Just seen your mention of silicon sealant.
    I assume this is the 'no smell' cure type? Standard sealant releases acetic acid (vinegar smell) during cure.
    The chemical release from 'smellicone' sealant can cause a lot of corrosion problems in electronics.

    As for leaving in a warm or cool place while the silica gel works its magic...difficult but I don't think there will be a big difference.

    If there are problems fitting big bags of silica gel into anything, there is another way.
    Calcium chloride absorbs a lot more moisture per Kg of product.
    It changes from flakes to a lump or gel.
    You would need to buy it already packaged in suitable bags. It is a single use method. No oven reset.
    A further thought is that calcium chloride is quite corrosive - if it gets out of the bag.
    I have encountered this compound in big applications - not in small applications.
    This stuff from amazon may be worth a look.
    https://www.amazon.co.uk/NATRUTH-Moisture-Absorber-Bags-Fgrance/dp/B0BHX32SN7/ref=sr_1_10?dib=eyJ2IjoiMSJ9.z7yKOZaItl_GYJbR8CsMEUKRrcPjXnItbLiAy9KimxmKfQ3vx20ZgZmLrsx9WZ0pnFpN3IYxiK4WWvB6IrftE1l7UMx4zcwapvFZbe4A7FnayMlKffZp8WEYIbOAlBL3Ll4v5OMEY8GRclSgni5jcTXfOgGlD6Sm0phE4kOE8MKm7_7UYSxTWrZ48LdfP7oQik3StPj956HcMRqZvvv6o8nY6VQNAtifCD-E1giX91o.GYATK0_cPTdaEDZ7TwCBgiuSxKM2eb9kWwY7hR_e1HM&dib_tag=se&keywords=calcium%2Bchloride%2Bdesiccant&qid=1711633995&sr=8-10&th=1

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  2. Silica gel absorption is a very slow process. Give it time.
    Sealing the housing on a cold dry day minimses moisture trapped, reducing the burden on the silica gel.

    Something else to consider. Do you know anyone who has a MIG welder? With a cylinder of argon based welding gas.
    Standard argon shielding gas for MIG welders is an argon & carbon dioxide mix. Importantly no water vapour.
    In some equipment I get involved with, the electronics (and more) enclosure is purged using either nitrogen or argon.
    High pressure cylinders contain dry gasses.

    Feed the gas in slowly at one side of the box, allowing it vent at the opposite side. OK not a 100% air purge but a big improvement.

    HTH, David.

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  3. A sealed camera case is a good solution. It is my preference.

    First check the state of all the weak points. Clear dome to box gasket. Box lid to body gasket. Lid screws are outside the gasket.
    Any PCB fixing screws that pass through the wall muct be sealed. Cable exit via well compressed glands - not connectors, etc, etc.

    If you reckon the box is well sealed, put a bit of tissue paper in there - not the camera.
    Give it a blast from a pressure washer. Not too close, but simulate a gale and intense rain day.
    This also simulates wet air being present at higher pressure than inside air.
    Dry off the outside. Open up and check the tissue paper is good as new. If not look for the leak.

    Silica gel absorbs only a small amount of water for it's mass.
    The amount of water held in air is temperature dependent and not a simple straight line.
    I read somewher that a 1C rise in temperature can allow 7% more water in air.
    Then how do you know it the silica gel is dry to start out? Are the bags new and from an assured source?

    Pop the bags (yes quite a few) into an oven at a little over 100C for several hours. Yes hours.
    That ensures all moisture is driven off. Unfortunately some bags melt their glue. But the product is cheap so don't worry.
    Immediately, while hot, put the bags into a biscuit tin or similar. For long term storage this way, add sellotape to seal the lid.

    Now take your camera outside, on a cold day. There won't be much moisture in the air - unlike your warm house with pans boiling on the stove, humans exhaling, shower running, etc.
    Stuff as much silica gel into the camera as you reasonably can and seal it.
    Lots silica gel ensures you can absorb a lot of water and leaves little space for moist air.
    I reckon that should do the trick.

    When diving and snorkelling in the sunny parts of the world, I avoided condensation by storing my cameras and open housings in the fridge.
    Immediately on removal from the fridge, the camera was sealed into the housing with of course little air space.
    This alone was a very good condensation preventor.

    HTH, David.

    • Thanks 1
  4. Yes the camera is much too far away from the scope.

    As a daylight test, point your scope at a distant object.
    Get rid of all the 2" & 1.25" stuff.
    Wave your camera (with live view) in mid air above the focusser.
    When you see a focussed image, you have a measure of how much/little adapter train is permissible.
    This will guide you on what components are allowed.

    I have used this technique on various scopes (newt, Mak Newt & frac) to get a feel for the size of the problem.
    In some cases it has meant rummaging in my bits box for the correct spacers/adapters. Hopefully this is the case for you.
    In one case it justified the purchase of a lower profile focusser!

    If you find you are only looking for a couple of millimetres, look at the main mirror fixings.
    Moving the mirror up the tube a little will push focus out.
    Depending on the scope, you have to go a long way to make the light spill over the secondary to any extent.

    HTH, David.



     

  5. Absolutely. All my threaded parts are bought outside of astro retailers.
    Right from replacing the SW alt bolts (remember when they used to be made from stale cheese) by decent stuff, to replacing rusty screws by bright and shiny.
    Springs and ball bearings on a flextube come to mind for affordable replacements.
    Being born in Yorkshire has helped with financial control.

    I'm not saying the few bits of bolts sold by astro retailers are a rip off price.
    The retailer has to either buy in the small packet of screws at a high price. Or buy a bucketful for a good price and hope he sells enough of them.
    He can easily spend the same time sorting out the right screws as advising on a ££££ scope package.

    However, we must remember that some people don't know about screw thread sizes and all that. They have to play safe.
     

  6. I had other things conspire against me this year, so missed the show.
    Fingers crossed for next time.
    Thank to all who have made the show possible, and those who have posted reports to let me know what I missed.

    In partcicular I note the photo by @Gfamily showing the sensibly located Pulsar dome.
    I recall it being almost an obstacle near the entrance at one of the Kettering shows🤣

     

    • Like 2
  7. A contrail comprises water, carbon dioxide and bits of soot. As the carbon residues are tiny particles how long is it before they fall to the ground?
    While carbon is in the sky, it will seed cloud formation.. I'm sure someone somewhere knows about this effect.

    I remember reading a long time ago about Australian farmers making daily reports on pan evaporation.
    This was on the orders of the government. Agriculuture department maybe?
    Something that started in the 19th century and continues today.
    Sorry I don't have all the details.
    The evaporation rate had gradually changed due to the sky being less transparent.
    I took a quick look to see if I could find the article. But no luck.
    Again someone may know more.

     

  8. Thank you for posting the article link. It is a much debated subject.

    At home I have a good view of a major high altitude airway. On a good day I can see a contrail start west of Liverpool (over the sea) and follow it beyond my Nottinghamshire overhead.
    I know where I start viewing by timing to overhead and assuming cruising speed, or more accurately using Flightradar 24 to track.
    Most contrails dissipate in tens of seconds, maybe a minute or two. Though on a few days, they can persist much longer.
    Then there is the question of dissipating beyond unaided eye view, and dissipating beyond heat retention.

    Think back a few years to the aviation shutdown caused by the (very long unspellable name) volcano in Iceland.
    We had a period of no commercial flying. I remember looking at the sky on more than one day after flying resumed, seeing contrails that were all but games of noughts and crosses in the sky!
    It certainly made me think about how 'clear' our skies are.

    • Like 1
  9. The 12V to 11V 'step' indicates one cell (of six) has shutdown early.
    Equal performing cells would give a gradual voltage decay.
    A bit of unexpected bad luck if it was a known brand.
    Definitely battery to the bin.

    You should find the lithium battery is good for providing high current.
    The other good news (given UK weather) is lithium performance degrades gradually with charge/discharge cycles. not the calendar.
    In addition, the self discharge is far lower than lead acid.

    A good choice for the replacement.

    • Thanks 2
  10. Some years back I converted an old Prinz scope to take (modern) 1.25" eyepieces.
    The not quite 36mm thread and Vixen adapter ring a bell.
    If I can recall the details I will add them.
    I do recall that when the fit was not quite right (couple of tenths of millimetres on diameter) I used a screw thread gauge as a scraper on the female thread to make things fit.

    • Like 1
  11. Methods vary between scopes, but I think this generic explanation of why you have to buy an expensive scope for Ha viewing is reasonable.

    The Ha solar scopes initially filter out unwanted wavelengths. Starting at the objective and refining further down the scope.
    Rejecting unwanted energy prevents scope heating. They remove the IR, the UV and most visible,  leaving a narrow red region.
    The narrow red is passed to the etalon. This is a really really narowband filter that is necessary to view the filaments.
    In addition, the actual wavelength has to be tunable/adjustable to get best views. Doppler shift - another word to introduce.
    Adjustment is by tilting the etalon, or by altering the air pressure inside, or by altering temperature.
    Tilt and pressure are immediate adjustments, temperature is slower.

    To get the etalon bandwidth into perspective, it is typically 0.1 nanometres (nM) pass. Double stacking reduces to typically 0.05nM.
    A visual Ha filter for night use has 50-100 times the pass bandwidth. So even if the energy rejection was done, it would not show the filament detail.

    All manufacturers have to select their etalons from a mixed materials bucket containing research grade, to landfill quality. It is the way the material turns out.
    This means if you get a report of first rate views from a scope type, if you go to buy another, it may be better or worse.
    In the early days of the PST, I read about someone going to a retailer and setting up on the pavement. Selecting from the 3 scopes in stock, and seeing very different results.
    In the early Quark days a lot of people returned poor quality product.
    At a show I asked how the complete Daystar Ha scope could sell for less than a Quark eyepiece. The retailer could not (or would not) provide an answer.

    HTH, David.

    • Like 1
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  12. On 17/02/2024 at 12:53, tomato said:

    Get them all set up in the same location, it would make a great photo

    Alternatively set them up, widely spaced, in a field. Call it the (Astrosoc name) Very Large Telescope Arrary.

    Oops - has that term been used elsewhere😁

  13. If you really want to spend on Ha, look at the Solar Observing section around Jan 2019.
    There are quite a few entries about when I was trying to upgrade from PST.
    Various discussions mentioned Quark, Lunt, Coronado, etc.
    Some of it is still relevant today.

    If you are happy to stick with white light, a Herschel wedge gives a lot of enjoyment for the ££ spent.

     

    • Like 3
  14. Bolting the Vixen to the Losmandy as described by @RT65CB-SWL would be my first choice.
    I have access to good drilling and tapping tools so it is easy.
    Not having sight of the Losmandy bar I don't know if there is drilling involved.
    The only contra indication is if your mount is on the weight limit.

    Option 2 (again drill/tap required) is a couple of short lengths of ali bar (1/2" sq?) on the old Losmandy fixings to space the Vixen bar off the OTA.

    HTH, David.

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  15. On 28/02/2024 at 08:57, Tomjo59 said:

    I do wonder how much of the regard for it is pure nostalgia though.

    I think that depends on the individual. Yes nice to watch the old ones. Interesting to see (incorrect) thoughts on what the lunar surface was like pre-apollo, and more.
    But just as fascinating to see first far side of moon images, first Mars close up images, etc.
    I remember when first pictures came in of Saturns moon Japetus. Though that may have been on the news and later discussed on S@N.
    Yes a dark side and a light side - but no sign of a 'Clarke' obelisk😁

    The current format requires lots of planning, large film crews, travel to distant locations, etc.
    How do you produce a programme that can report on recent events?

    If the show had a section based around someone checking up on recent events, jumping on a train to the studio and sitting in front of a camera with minimal props....
    Oops - been there and done that. Thank you SPM for your many short notice reports.

    How can the current production method provide an informed presentation about (for example) the recent toppling moon landers?
     

    • Like 1
  16. This is yet another thread where a member has asked for advice and not returned since posting.

    If I had real concerns about possible kit damage, I would not walk away from the thread.

    On behalf of the OP I am going to thank all those SGLers who have freely given their time to offer good advice.
    On Sunday when I first saw the thread, I was on the verge of taking the covers off my S50 to look into routes for water ingress and how best to deal with it. But I was out all day.
    I am glad that I did not make the effort. It also makes me think that in future I should check post history before taking time to offer help or advice.

  17. The programme title is somewhat misleading.
    It suggests 'these are things to see in the coming month'.
    Rather than the big budget global tour.

    Very affordable technology could be used to improve on the early presentations where SPM sat at a desk with cardboard cut out planets and the like.
    No need for travel. Though it has its place to show us the new large telescopes, etc.

    Given that very few people around today saw the first (decade or more) programmes, much content could be repeated for the 'newcomers' who have only got interested in the last half century.
    I missed many early years of the programme due to it being way past my bedtime and domestic video recorders had yet to be invented.

    Then again. Why not just put more of the old programmes on iplayer.

    • Like 3
  18. Yes giving them somewhere to put their hands is very good advice.
    Much better than 'eyes are for looking - fingers are for touching'.
    I once had a visitor to my shed who without warning grabbed the scope tube and swung it to look through.
    Strangely the object centred in the fov did not follow the scope🤔
    A little annoying as slippng the mount clutches meant I lost alignment on the goto😡

    • Sad 1
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