This evening was actually clear. Last night was too, but, we had plans that kept us from observing. Over the past year, as many of you are aware, we have been doing upgrades to the Mini Tower. We replace the factory bearings with high precision Timken roller bearings. The difference is actually quite impressive. Don’t get me wrong since the factory bearings are good for what was intended. The Mini Tower was intended to be a very high quality Grab-N-Go mount. For that it has no competition. However, some of us like to push the limits. I am one of those people. The new bearings have allowed us to use heavier instruments than ever thought possible. They also allow for better targeting and less vibration at very high power. In fact, we have on many occasions, loaded the upgraded mounts with double the weight that is considered the limit by the designers. In addition, our upgraded mounts work in the EQ mode. The factory units simply cannot function in that mode because the bearings are not up to the task.

Tonight we achieved my personal Holy Grail. We mounted my 1965 4” f/15 Jaegers refractor on a modified Mini Tower. Until we made some changes which included the Timken bearings this was just not possible. It isn’t the weight that was the problem. It was the moment arm, or, length of the telescope itself. On all previous attempts the long tube would strike the tripod legs. If we moved the OTA forward in the rings far enough to clear the legs then the entire thing would over load the clutches or cause the worm gear to push clear of the worm wheel. The noise that this makes is quite startling to say the least.

As I mentioned, we had to make some further changes internally before we could get the OTA to work. We also needed to add a temporary weight to the eyepiece end to help achieve a good balance. That was what really made things work well.

Tonight, we set up the upgraded Mini Tower on our heavy duty tripod which originally came with my Atlas GEM. The Atlas has found a new home, but, the tripod has remained. This is quite similar to the new 2” tripod that is included with the just announced Mini Tower Pro. Actually, almost all tripods of this size and design look darned close to identical. After all, there is only so much that one can do with a tripod.

The first image shows the OTA mounted on the Mini Tower as it is sitting upon the Atlas tripod. I also installed a tripod extension to raise the mount up to gain the needed clearance for the eyepiece end of the OTA. It also helps to get the EP up to a more comfortable viewing position. It was still necessary to sit in a chair when observing near the Zenith, but, at least we didn’t need to kneel in the dirt any more. With a shorter OTA then this becomes even more comfortable.

4 inch f/15 Jaegers on an UPGRADED Mini Tower.

Note in the photograph that we have replaced the small factory CW shaft with one that allows us to use a Losmandy CW. That weight is about 12 pounds. I should have used more, but, I forgot to bring a second one. OK. I THOUGHT that I had forgotten to bring a second Losmandy CW. It was hiding in the bed of the truck. Ooops! Regardless, the Jaegers has a weight of about 25 pounds. The extra ballast that is held at the EP end with duct tape is another 7 pounds. The DW shaft is about 4 pounds and the CW is 12 pounds. That is a total load of 48 pounds! Like I said, just about double the factory recommended limits!

Notice the Losmandy CW and shaft?

We leveled everything after all of the equipment was in place. The power was turned on and we set off to look at Jupiter. Since we did not go to the trouble of doing a proper north-south alignment the mount was off a bit. Not a problem. I just slipped the OTA against the clutches and Jupiter popped right into the EP. I used the SYNC command to center and lock in the alignment then headed off to M27. It was well within the FOV of the 2” 26mm SWA EP that I had installed into the focuser. I did the SYNC command once more and then started roaming around the sky. Every item was well within the FOV. The sky conditions were rather hazy and the Moon was making the seeing even worse. Still, we hit everything that we called up. We went to M13, M3, M15, M31, M103, M76, M56, M57, and on and on. The mount moved that 4” f/15 OTA around like it wasn’t even there!

While Stephen and I were doing this, Rags was popping off objects with his 13” f/4.5 DOB. He was finding things by star hopping and using charts. We just kept banging off objects with our trusty little GOTO controller on our upgraded Mini Tower.

Shortly after we had begun our observing session, Jupiter went behind a small tree and was not visible for about 90 minutes. Once it was again visible we sent the upgraded Mini Tower over to it and then jacked up the power. We played with a number of EPs, but, the best image was seen with an old Edmund 12.5 mm Orthoscopic and a 2x TeleVue Barlow. We used a TMB 6 mm Super Planetary EP and kept swapping between the two. The Edmund EP edged out the TMB with more contrast and more details visible. During this time we never had to re-center the image. The upgraded Mini Tower held the Jaegers right on target the entire time. We did find that focusing was a bit of a challenge because the old rack and pinion unit that is currently on the OTA just doesn’t work too well. It will soon be replaced with a newer two speed Crayford style focuser.

That's dew on the OTA!

We finally decided that the viewing conditions had deteriorated enough to call it a night. Also, Rags needed to get some sleep because he had to go to work in the morning as do we. The mount was sent to the park position and we dismantled the equipment, put it all back into the bed of the truck and headed home.

The whole point of this “experiment” is to prove that the Mini Tower is much more capable than ever imagined. With our upgrades it can equal or beat a number of EQ mounts that are quite popular. Additionally, there is not ONE Alt/Az mount with GOTO capabilities that can even come close to the upgraded Mini for any money.

Now, for the next step in the evolution of the Mini Tower, we are looking at more powerful motors! This should be even more fun!!

CS

Steve