Sunday 2018 March 11

video signal noise on the old cable

More work continued on the Tardis Observatory this weekend.

The eastern door hinge mounts were replaced with better, stronger and thicker wood, as the door was sagging just enough not to want to close too much.

Thanks to those with comments about the video cable for the mallincam finder.

arrived on Friday and is a BlueRigger Dual Shielded Subwoofer Audio RCA Cable with Gold plated connectors – 15 Feet for $14 replacing the mallincam provided 25′ video/power cable combo.

It was *much much* better and all of the video noise disappeared. Next is to try and move the power supply closer to the camera and get rid of the 25′ combo cable entirely! (image to follow)

We attempted to align the scope, videofinder and telrad Sunday afternoon, but met with failure as the sbig st402me camera, even at 0.04 sec exposures, was overwhelmed and overexposed to the max. We then covered the gap in the OTA side panel. still too bright. Added a 4″ subaperture cover, still too bright. Replaced that with a 2″ aperture mask. still too bright. Stopped down the videofinder lens all of the way.. still too bright.

Tried it again after sunset. We were able to locate on the cell tower (the only thing this cell tower has going for it so far)secondary light, focussed, centered, then adjusted the video finder mount to centre as well, and then the telrad.

*all* other moving parts have been inspected and push/pulled around and everything looks tight.

Slewed from the NE to sirius… and the telescope optics and the video finder were not aligned anymore.

arrggg! More repeat tests the next time out to try and discern some pattern to this problem.

The building is still rolling well.. too well… once rolling, it does not slow down nearly as much due to friction… and it stopped so suddenly at the end of the closing run the video display fell to the floor! Oh well… can’t complain about an easy moving building!

On the other observatory

As mentioned earlier, we discovered a big issue on one of the SCGO rolloff roof rails… it had a huge rotted section maybe 2″x16″ near one end.

You could see daylight through the board and poke your fingers through it!

It is approx 15 years old and the 2″x6″x8′ was sandwiched in between a 2″x4″ “fence” on the outside, keeping the wheels on track, and it had another 2″x4″ on the inside, to expand the width of the track for the wheels.

We suspect the inbetween area got wet and stayed that way and rotted out because of it.

This one was replaced on Sunday with a new pressure treated 2″x6″ and the “first roll” was completed later that same day. Not too bad. A few tiny fixes here and there… will probably add an inside 2″x4″ again to expand the track, as the wheels do tend to come a little too close to the edge at times.

Another tweak or two and then we will probably replace the other rail as well next weekend… just to simplify everything. It took only an hour or two for the first one.