Carbon Brush

Not an expert. But an AWR drive user. I have a vague recollection of seeing this sort of problem a few years aback, but can't remember the details, or how I sorted it. Sorry. It was possibly something related to approach direction being specified. Yes I have seen this problem recently. I did not investigate because it showed just before I started a mount strip for maintenance. This is still in progress. I guess there are two immediate questions. Are you using the latest firmware in the handset? Have you dropped an email to AWR? Hopefully someone more helpful and informed than me will be along shortly. David.

Sold to GKA in Norway. Thanks you Geir.

But it will probably finish at 5pm again. You can pull off the road on the way home to try out your new purchases

Given Michael's comment, you can see why I rarely post about new items in my shed.

Yes fortunately another hit on a quiet part of the globe. Given the location, I have no doubt the US military picked up the sounds and atmosphere ionisation with ease.

Checking on shipping to Norway.

An excellent day. Thank you to all the exhibitors who made the event financially possible, and to the unseen unpaid people who I am sure were there to make it happen. It was great to chat to suppliers. Some of whom who were just web pages until the day. Same for the visitors. I enjoyed a rummage on one or two stalls with 'junk'. I mean used equipment in less than pristine condition. Then of course there are the big products that I cannot ever afford, but don't have a use for. But still good to look at. Looking at the way products were displayed, comparing to other exhibitions and events, I reckon the astronomy folk must be honest. There were lots of small expensive items that were not screwed down. Eyepieces, cameras, etc. I sincerely hope this trust is never betrayed by visitors. It made for very relaxed viewing. Being able to closely examine items without a salesman pouncing is great. I managed only one talk, obtaining the last ticket for Robin Glover. Excellent coverage of the subject with little time for note taking. Fortunately this is now available online. I really hope this show will be repeated for 2020. Whether looking for specific items, a general look at equipment, or attending talks, or catching up, it was an excellent day. Badges next year to aid recognition? Even if made individually.

I have read the posts an make no pretence to understand the performance and limitations of the various mounts under discussion. Taking this aside, if I am understanding the descriptions of the encoders correctly, their difference to mount performance may not be well understood. Encoders come in tow basic 'flavours' incremental and absolute. The term incremental being replaced by 'relative' in some astro circles. An incremental encoder contains a disc (glass or plastic) with a large number of lines photographically printed. On top of this disc are two small groups of matching lines. The two groups are offset by a 1/4 line width. A light shines through these to small photodiodes. As the disc turns, each group produces bright/dark signals. This is where the 1/4 line offset comes in. The two light/dark waveforms are 90deg out of phase, which allows (by simple electronics) direction to be determined. The resolution of these encoders tends to be restricted by the disc diameter. But can be several thousand counts/revolution. An absolute encoder can be based around the same sort of idea of a disc and photodiodes. However, the disc has a pattern that reflects binary (or other code) counting. Not a simple set of radial lines. This means that the number of photodiodes needed to extract information goes up with resolution. A 1024 step encoder requires 10 photodiodes, 10 amplifiers, etc. The compromise between number of tracks (photodiodes) and accuracy is often an issue. An incremental encoder is much lower cost to manufacture, and will be more reliable in the long term. They are accurate and give consistent results. I have used them in large machine controls to measure position to 0.01mm. The absolute encoder has the benefit of knowing where it is after a power loss. An increment encoder has to rely on a datum mechanism after power up. Usually this is another photodiode that gives one narrow pulse per revolution, that is coincident with a crudely set microswitch, or proximity switch. In conclusion, mount performance is not determined by the choice of absolute or incremental encoders as such. It is the way the encoder information is handled - assuming all else (mechanical, etc) is equal. Hope this is useful. David.

The ability to breathe non-standard concentrations of gases is fairly well understood by those involved. Scuba diving, aviation and medicine are all examples of non-standard gas breathing. It is not just the ratio of gases that needs to be considered, but the pressure, or specifically the partial pressure of each gas resulting from the mix.

Go for a physically small iron with about a 50watt, temperature controlled element. By selecting different bit sizes, you can cope with most jobs from surface mount components up to big wires. But not plumbing When soldering, the traditional 60/40 tin /lead solder is easier to use. It melts a bit cooler than lead free. I have though recently seen a notice from one supplier that he will only provide this to business customers, not retail. If you grab a few bits of heat shrink sleeving in various sizes, these are useful. You can sleeve the centre pin contact in the phono plug to avoid shorts if the cable gets twisted. You can pack out the cable outer if it is a poor fit for the connector body. Sleeving can provide a strain relief to prevent excessive flexing. Don't forget. You can practice if have a spare phono plug and wire offcut. If you are not happy with the result, just trim a couple of centimetres off the wire and try again. Hope this helps, David.

If you do not have the soldering skills or tools to connect into a phono plug then ask around locally for someone who can do it. Splicing reliably and neatly mid-cable is (I think) more difficult.

Still available?

Looking briefly in the 'supplier reviews' Cheapastrophotography' get positive mentions. I did not get any hits for DSLR Astro Mod. But I did not try all permutations so maybe it was my search string.

Sorry not an offer to buy. I bought one a few months back! Hopefully a couple of comments a potential buyer may find useful. This is a well constructed item. All steel. No flimsy plastic. It does the job well. To get the trolley home, the 'T' unbolts just forward of the joint to the rear cross member. This leaves you with two long pieces of steel, with wheels. The wheels are retained by split pins. So given 5 minutes, a couple of spanners and a pair of pliers, it fits into a car with the seats folded. Or even on a roof rack, or bars. A useful (I think so anyway) mod is 3D printed hand knobs to fit over the steel T bars for jacking. If the buyer would like a copy of the 3D file, just ask. Hope this helps you to find a buyer

To Chris (Lockie). No not your scope. A different Lunt scope! The presence of a similar scop that was not actually available may have contributed to the slow sale of yours. One of the reasons for me starting this thread. Clear (sunny) skies, David.