Carbon Brush

I sold a 120mm F8 refractor a few years ago. Not a small scope that can be hidden easily. It was little used, complete with original boxes. I met up with the buyer in a pub car park, late at night, after he finished his work shift. The transaction was very hurried, no inspection, no questions, just a bundle of notes pushed into my hand. He took the scope & accessories. Explaining he could not take the boxes. He had only a few minutes to rush home and get the scope hidden inside before his wife got home🤣

Yet another reason for building an observatory🤣

If the bin hasn't been emptied, fish it out😁 A total failure has to be a broken connection or failed fuse in there somewhere. I'm sure it is repairable in the right hands. Anyone local to you into amateur radio or electronics as a hobby? Or anyone at your local astro club knows a bit about electrics?

Suggestion. Remove the battery positive (red lead) for safety. Follow the battery positive lead to the circuit board. It looks like the first port of call may be the circuit board. You can see at the left there is a substantial area of copper marked '+. Is this where the wire runs? If so, from there the battery +ve is distributed to various places via fuses. Remove the PCB (two cross point screws) and look on the other side. Several fuseholders? Maybe one has a blown fuse? HTH, David.

Presumably the kit did not work at the outset, which is why you swapped out the battery? What is the history? Owned from new? Bought used? Used to work? Left in a cupboard for a long time? Did you perform any tests (voltmeter, lamp loading, etc) to establish a faulty battery before the swap out? Do you have a multimeter to carry out basic checks on the internal wiring? Sorry if this sounds like a grilling but the thread started asking about one wire. There is obviously more going on. When my (usually overseas) customers ask for help , I always say.... The quality of advice we give is entirely dependent on the quality of the fault description and completeness of the information you provide. HTH, David.

A radio antenna does seem likely. Unless you want to start tracing part of the PCB, it is better to ask a simple question. Does the box do everything it should? If yes - use it. If no, look further and keep asking the questions. HTH, David.

Any filter is fitted after the wedge. That way it only has to deal with a tiny fraction of the suns energy. The ND filter is immediately after the wedge. In some wedges (including Lacerta 2") it is impossible to remove without dismantling the wedge - a safety feature. After that, it doesn't matter about order of filters. Unless someone knows otherwise? HTH, David.

Another vote for the wedge - not film. I use a Lacerta Wedge. Unlike others, these are a 'Brewster' Angle. This means the light is strongly polarised. I can then use a single polarising filter for extreme brightness control. If you read the Lacerta hype, you wonder why others don't do this. I have asked retailers about 90deg vs Brewster - and asked someone giving a talk at PAS. But nobody has the answers. All I can say is that I have been happy with the Lacerta/Brewster. But have not done side by side with others. Another useful filter is a solar continuum. This dims the image a little if you have a 'too bright' wedge. Importantly you start to see the granulation. Choosing a 'too bright for visual' wedge is a good idea. If imaging you can use a fast shutter to freeze the turbulence. Dimming an image for eyeball comfort is easy with a polarising, or further ND, or continuum filter. If you go for a 2" wedge, think about light path. It is something like 115mm. You can run out of focus on some scopes. HTH, David.

Wow! If you had only spent a few minutes fiddling around, allowing the star to move away from the cable, you would have been left wondering what you had done to fix the problem🤔 Glad it is all sorted.

Yes I wonder about suitability for UK use. The Dwarf spec even gives 10C minimum. UK Summer use only? Can't fault these devices as 'plant on tripod and get quick results' type of equipment. Given the number of 'new to astronomy' people who want imaging before eyepiece viewing, I'm sure these things will sell.

Presumably the cameras bought from the Dwarflab site incur import duty and VAT? Anyone been down this route? Looking today the site is offering the deluxe at £424 incl shipping. 365 are asking £539 incl shipping. In other words very similar prices if there is VAT and duty to pay - then of course there may be carrier/importer fees. My interest is more daylight for moving wildlife - have already spent on astro mounts and cameras.

Rather than wasting clear nights - or having to wait for a clear night - why not use an artificial star? These do need to be placed a long way from the scope. Some are usable in daylight. I took a glance at FLO offerings and you can spend £19 or £117. Probably worth looking on SGL for others experiences and comments on these.

Anything you see and enjoy - especially something new - is worth a mention.

I think Peter has a valid point. The vertical artefacts differ significantly between intra and extra focal images. Skywatcher have a habit of fitting shiny drawtubes to their (dark grey painted) tubes. If this is happening, then black paint on the drawtube and/or tube flocking will help. An interesting trial would be to put a bit of black card on the drawtube - held by an elastic band.

Hi Steve. Yes easy enough. There are screws in the black paint just forward of the white ring. Shown in pic 8106. This is a 200P and there are 6 screws. Indicated by the screwdriver. Moving to pic 8107. This is a 250P. Same principles, just a bit more support for the mirror in the centre of the cell. If you look in the for sale section, I have listed a 300PDS tube. Again 6 screws. Slightly different again mirror cell centre. But the same principles. Usually the screws are M4. I usually put a tiny bit of silicone (clear) grease on the screws on reassembly. Work on the assumption (as I do) that the grease is made from a platinum/gold alloy and you are a miser😁. The grease won't melt and run out on a sunny day. It prevents binding from corrosion in years to come. You are of course leaving the scope out on dewy nights🤔. HTH, David.

Another easy enough test is to remove the mirror cell completely and check for mirror fit/clearance. Just a few screws to remove from the periphery of the tube. If you mark the tube and cell (masking tape) so you reassemble in the same orietation, it will minimise collimation effort. You should have sub millimetre lateral clearance to the mirror at room temperature. The clip screws should loosen the clips with a fraction of a turn. If not you are pinching the mirror. If in doubt, re-assemble with the mirror definitely loose. You may get an off collimation star test result - but no spiky bits this time will indicate you had mirror pinch. HTH, David.

I'm surprised no mention has been made of the temperature when checking, and the materials used in the mirror cell. Assuming a mirror glass has zero expansion with temperature. It is only the metal cell we need think about. Thinking about a 300mm diameter mirror, maybe 30mm thick. If the cell is made from (expanding with heat) metal, it needs to have a gap around periphery at room temperature, so it closes to near enough zero when cold. If the gap isn't there, the mirror is pinched when cold. Taking an aluminium cell, it needs to be about 300.14mm to hold a 300mm mirror at 20C, then grip with zero clearance at freezing point. In other words something like 0.14mm around the periphery indoors will be good for a cold UK night. That is 0.07mm on each clip, regardless of the number of clips. This sort of number is business card, recycled xmas card, rather than credit card. Obviously a smaller mirror can have lower clearance. Or if you set up the spacers when the scope is already cold, you can use a smaller clearance. Cast iron has about 1/2 the expansion of aluminium so requires less clearance. I haven't looked up aluminium alloys, or steel. But I don't see the numbers being hugely different. If you have thin cork, or similar squashy material holding the mirror edges, if you lose the thermal clearance, then initially the cork/sponge squashes in preferences to the glass deforming. As for the screws holding the mirror front to back. Being only around 30mm long, the numbers above can all be divided by 10. The pads are to prevent mirror scratching. In other words a mirror has bit of side to side movement when checked indoors, but almost no front/back play. Just my uneducated and ill iformed thoughts🤔 David.

I got into spending on a decent scope about 20 years ago. At that time motorised mounts had a big price penalty compared to manual. As for goto - if you need to ask the price and all that. Strangely I don't remember dob mounts being popular among the big manufacturers. Or is it my defective grey cells? I did own an ETX90 that on paper appeared to do everything, But experience with this, and other goto mounts led me to the opinion that goto was a faff. Having to set the date/time and align every time out. Some earlier Meade handsets used to corrupt memory if they got a dodgy 12V connection. Requiring throw away, or an expensive programming adapter. Today we see a lot of starter type scopes where the electronics cost means compromising on the mount and and optics. But when your mount has gps or talks to your phone, a lot of goto setup faff has been addressed. To the future. There is a huge amount of amateur equipment in the world. A lot with good optics. Will more people look at putting an old optically good scope on a new clever mount? Will the clever image processing get used more to correct for mount errors on a visual scope. We already see guiding used when imaging. Why not use guiding when visually observing? I have no doubt the visual enhancement aspect will move forward. A scope that knows what object you are looking at and puts the effort into enhancing only the parts of the spectrum relevant to you. We already fit filters on eyepieces for visual. This could done for an EV scope with it's own filter wheel. As we age, our ability to extract detail from dim objects diminishes. Electronic eyepeices of any sort can help here. No need to worry about dark adapting for faint fuzzies after viewing the moon. Sadly I think that increasing light pollution is going to restrict our UK experiences. I don't know if it is the rose tinted glasses with fond memories of the past. But I don't think we get the clear nights that we used to see. Climate change? I have not researched this, it is just an uneducated and biassed opinion.

A power tank/bank (whatever brand) that has a 12V lead acid battery will not damage the mount. Just ensure the lead to the mount is fused in case of shorts. A power tank/bank of unknown internal construction, except it contnis lithium cells carries risk. It can impose voltages outside of mount normal operation. Note the RVO offering is 12V 17AH = 204Wh. The amazon device claims only 99Wh. Unless you really need other than 12V, an easy decision really. HTH, David.

Looking forward to your reports. I have the older daylight only model.

Hi and welcome to SGL. Before jumping to the BUY IT button, a few words. Whatever you buy, get it from a speciailist astronomy retailer. He can provide after sales support. The specialist (in general) won't sell you the wrong scope - provided you talk to him. Check out the site sponsor, FLO (top of page) they have a beginners scope guide. Do not buy from the likes of Amazon, Ebay, Currys, department store, local selling sites, etc. If you don't know what you are looking for, you can easily buy a lemon or something only fit for landfill. Even if you buy a branded scope new from the likes of amazon, they can't help to resolve problems - only offer a return/refund in a short time. HTH, David.

They might be empty boxes. Just had an idea about the next astro items I sell😁 Sorry just looked at his listing on ebay - there do appear to be box contents.

Based on my experience of ebay inaction after reporting scams, I would not be surprised if they wait for someone to lose money, or them get 100 'dodgy' reports. Thank you Paul for posting.

To add.... USB2 is slower data than USB3. That makes it more tolerant of cable losses. If you are sending relatively few commands, like controlling a mount and sending a few camera commands, a slow data rate is fine. If you want to live stream high resolution video, you need a high data rate. Cheap cables often give problems when pushed to the limit. A 'known name' screened cable is essential. The cheap stuff is best regarded as OK for low power charging, or a short length. In the grand schemme of astrophotography spend, and few clear nights, why chance it? If you have spent >£1000 on a scope, mount and camera, why fuss about even £100 on decent cables? HTH, David.

Sorry to hear the mount has failed. I think the long service life shows the build quality. Should you decide it is scrap, then please let me know. I have one in (differently) non running order so am interested in making a package.