Astofix and wixey

[lawrie]

AstroFix and Wixey

This may sound like a comic cartoon strip but I would like to review two systems useful particularly to owners of Dobsonian telescopes (who haven't already added Altitude/Azimuth scales).

The Astrofix system has sensors for both azimuth and altitude and is intended for astronomical use. The Wixey digital inclinometer is intended as a woodworking accessory and can be used to indicate altitude only.

Astrofix

This consists of a small diecast box about 3in. by 2in. by 1in. which contains the digital readout panel, the electronics and the four rechargeable Nicad batteres. A ribbon cable about 1 metre long connects to this box to the small black plastic azimuth sensor. The device comes with a mains charger and a short instruction leaflet.

The diecast box is fixed to the telescope tube with Velcro pads. The azimuth sensor also uses Velcro and can be mounted either directly on the turntable of the telescope mount or affixed with a plastic L piece to one of the mount sideboards. The instruction leaflet gives illustrations.

Operation

The leaflet gives clear instructions for calibrating the system, It involves first setting up and correcting the azimuth sensor and then zeroing the altitude reading with a spirit level. There are four clearly-marked push-buttons on the main box to switch the system on and off, to calibrate the azimuth and altitude sensors and then to switch between altitude and azimuth readouts. The display has a green backlight.

In Use.

The system must be calibrated first and if the telescope is permanently installed say in an observatory, then there is no need, says the maker, to recalibrate at the start of every session. Only if the batteries are changed or allowed to run down completely is it necessary to re-calibrate the system.

In fact I checked the calibration every time I started a new session, particularly the azimuth. In practice the azimuth sensor was affected considerably by the steel tube of my Dobsonian. Following suggestions in the instructions, I learned to set the telescope tube to about 30 degrees altitude before performing the azimuth calibration. Then when setting the coordinates for any object I would first set the telescope tube to this position before moving to the required azimuth, and then setting the required altitude. This was a little annoying and I would sometimes forget to do this when moving to another object and then wonder why I couldn't find it! But doing this soon became "second-nature".

The setting accuracy was usually to with 1 or 2 degrees azimuth and at moderate altitudes with 0.5 degrees which usually enabled me to find the object within the field of view of a low power eyepiece or close to it. However as the altitude increased to about 50 degrees or more the altitude readout became less accurate. And so having zeroed the altitude reading at 0 degrees at the start I found it best to re-calibrate it again with a known star at about 45 degrees if intending to move higher.

The backlight was a little too faint to be read easily and I used a hand torch to read the display.

Build Quality.

To be frank this was disappointing. It appears to have been put together in someone's private workshop (or on his kitchen table) where making this device is a paying hobby. The ribbon cable had no protection where it left the main display box and where it entered the azimuth sensor, it was sealed with what appeared to be a blob bathroom tile sealant. Inside the display box the battery holder had been cut away in part to accomodated electronic components. The printed circuit board was taped to the box lid.

Impressions

Apart from the build quality already mentioned, the unit worked reasonably well and in the absence of any other means of setting the telescope, it certainly served its purpose. Only at high altitudes was it inaccurate: at 90 degrees the altitude readout was more than 6 degrees low. The cost at about £90 post paid is reasonable - just.

Wixey

This is an Amercan-designed Chinese-built unit of an altogether better quality. It is about 2in. square and 1in. deep and is far more professionally designed, constructed and presented than the Astrofix. However it is intended for setting precision angles for wood working tools. For astronomical purposes it is useful only to provide an accurate altitude readout. The maker states that it is accurate to 0.1 degree. The instructions were on the card which came in the blister pack. Also the CR2032 button battery, and a spare, was included, as was a soft case.

Operation

The Wixey has two strong magnets in its base which attached the unit firmly to my Dobsonian's steel tube. It has two buttons: an On/Off and a Zero Set. As with the Astrofix I set the telescope tube horizontal with a spirit level, pressed the zero button, and that was it. It does not have a backlit display but as I had to use a torch with the Astrofix, it was no great inconvenience. Thereafter, using the Wixey for altitude and my azimuth -marked baseboard, it was easy to find any object well within the FOV of the low power (X37) eyepiece. The maker's stated accuracy was always correct. The readings at both 0 and 90 degrees were consistently "spot on".

Build Quality.

This was very good. There were no screws for the curious to undo and tinker with the works. The readout was clear. The general feel was of quality and reliability.

Impressions

As with the build quality it gave the impression of being a rugged and reliable unit which would give long service. The cost, about £28 post paid is very reasonable. (Compare this with so many astronomical acessories! ) The distributors are in Essex, (enter Wixey in Google), and delivery was fast. Altogether I am very impressed and can thoroughly recommend it. Now if only they did a comparable azimuth sensor!

Sky Tests

It is worthwhile checking occasionally the readouts (of either system) with stars of known altitude and azimuth. This gives an indication of any consistent or random errors. With the Astrofix in particular, it is a good idea to find a nearby bright star of known coordinates near to the desired object first, to allow for any errors. It is fair to say that both devices pointed up errors in my original paper tape atitude scale.

[Moonshane]

hi Laurie

this is a really detailed and interesting read. I am most concerned about the build quality of the Astro-fix unit (which I have been most tempted to buy recently) and am now more 'turned on' by the Wixey on the basis of your comments. I may invest in a digital compass and Wixey now instead of the Astrofix.

[simon84]

I've had two Wixeys myself and was able to use my first one to aid installing 6 meter tall shopfronts when I did that for a living. I could zero the wixey on the bottom section and then use it as a guide for positioning uprights. They are very reliable and very accurate. For big jobs when my laser wouldnt fire a line far enough this made a very handy replacement.

I'm about to start using one of them on a dob and when I build my dob base I will be adding a scale as I already have true north marked in my garden.

Time will tell how accurate it all is but overall the Wixey is great.

Never heard of the Astro Fix and after reading that am glad I havnt.

Cheers for the write up.

[Makron]

Interesting!

Thanks for the review