P75 - Trident Direct Friction Drive Mount

The JTW P75 is a direct friction drive mount that breaks the traditional rule that a heavy payload needs to break the bank. It's an engineered-for-purpose mount that is meant to be extremely economical, to do one job well and to do it reliably. This mount has a photographic payload of 75 kg.

It is nearly entirely made in the Netherlands and with love and a lot of enthusiasm.

We are proud to be the first exclusive dealer for JTW Astronomy in German speaking countries.

The purpose of this mount is to open doors for astronomers and astrophotographers who require an observatory class mount without the significant investment that's usually required. This mount has very high performance and can also be upgraded significantly, it has an open source control system and can be maintained with COTS (commercial-off-the-shelf) components. This is JTW’s breakout system, to demonstrate what JTW products are capable of and to give a preview of what our bespoke systems are capable of.

A straight and efficient solution for high payload without unnecessary extras.

Engineered for purpose means that you are not paying for performance that you can't use in the real world. JTW engineers all have an industrial background, every step of the design process is made with considerations to production, machinery, tooling, material selection and material costs, etc, this is a very efficient way to manufacture a product and results in high performance for a low cost. Our product testers are astronomers who also operate in the real world, user experience is also a large factor in the design of our products. 

Highlights of the P75 Trident include :

• 75 kg photographic payload
• Based on the proven OnStep open source control system
• Ceramic-metal hybrid drive
• 180 s unguided imaging out of the box*
  • *Depending on setup, some systems are more difficult to carry than others, e.g. refractors with long focal lengths.
• Direct friction drive, no reduction rollers to add to periodic error
• Preloaded precision roller bearings throughout 
• 0.12" Resolution
• 10° per second maximum slewing speed, 7.5° advised
• 3" Peak-to-peak periodic error (16 minute period)
• 8" Peak-to-peak periodic error (24 hour period)
• 23-bit or 24-bit absolute encoders supported (upgrade option)
• Stainless steel drive available for difficult environments (coastal or dusty)
• On-the-fly changes to microstepping for fast slewing or fine tracking
• Missed step detection
• StealthChop™ silent running, no more stepper motor chirping
• <0.2 px guided performance
• 0° to 90° Latitude range
• ±5 Degrees of Azimuth adjustment for polar alignment
• Aerospace aluminium and stainless steel construction
• Sustainable metallic, textured powder coated finish
• ASCOM and INDI drivers
• Mobile app turns any mobile device into a smart handpad
• WiFi and USB

Features JTW has added to OnStep thanks to a fantastic collaboration with Howard Dutton of OnStep:

• Support for industry standard BiSS-C & SSI protocol absolute encoders
• Ability to tune motor currents without reflashing the OnStep firmare
• Ability to tune motor ticks per degree without reflashing the OnStep firmware
• Ability to tune encoder ticks per degree without reflashing the OnStep firmware
• Open loop positioning, absolute encoders used for pointing. Negates the need for home sensors and retains position after power loss

Upcoming features in the next software update, available free of charge -

• Closed loop positioning. Uses the encoders actively in the tracking and negates the need for guiding. 

Upgrades

• 23 bit absolute encoders - 995 euros without VAT
• 24 bit absolute encoders - 1195 euros without VAT
• Stainless steel drive wheels - 595 euros without VAT
• Additional counterweights (12 kg) - 125 euros without VAT

*Depending on setup, some systems are more difficult to carry than others, e.g. refractors with long focal lengths.

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Some real (not marketing optimized) facts:

A quick cellphone video of a Trident slewing at maximum speed (10 degrees per second) at about half payload ~40 kg plus various counterweights. This is a good test of the tuning of various parts of the system. The chirping noise is the motor drivers changing ratio on the fly, this allows the finest tracking and the fastest slewing. 

https://fb.watch/fzZ1_j_5Wk/

This is the flattest graph we've seen in 10 years of business! 

0.07" RMS on RA (Y-axis) and only 4 guide corrections in nearly 4 minutes. 

Takahashi ED180 Epsilon on a JTW P75 Trident. Short focal length sure but it shows the intrinsic precision of our direct friction drive system. 




Some pictures of the inhouse production of JTW: