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Questar 3-½ Electronic Dec Control 151,558 bytes The Questar 3-½ Declination Motor, sometimes referred to as a Motorized Declination Vernier Drive, is an option for use only with those Questar 3-½ Fork Mounts that incorporate the Questar Powerguide II drive and control system. The original internal Powerguide of the 1980's and its successor the Powerguide II are each an electronic drive and corrector powered by one 9 volt battery that allows the user to operate the Questar at a precise Sidereal or Lunar rate anywhere in the world - north or south hemispheres, completely independent of wall current or other external power sources. The Powerguide also provides the means to vary the rotation speed of the Right Ascension motor to make fine tracking adjustments.

The development of the 9 volt Powerguide systems was accompanied by the introduction of an optional Motorized Declination Assembly for the Questar 3-½ Fork. This accessory includes a Declination Hand Control wheel that replaces the original, and the Motor and Support Frame that is attached onto the Fork Tine meshing with the new Declination Hand Control wheel. The Motorized Declination Assembly compatible with the 3-½ fork mount Powerguide II is P/N 19526.

The manual gearing knobs provided on all Questar Forks are useful for making adjustments of the telescope up or down (Declination) and left or right to center the telescope onto one target or another. But for astrophotographic applications and in some other instances it it necessary to make very fine adjustments - so fine as to be visually imperceptible unless one is looking through the telescope. Any touching of the manual controls may introduce unwanted vibrations, and may not be as precise a motion as is needed. And so the the Powerguide II when equipped with the optional Motorized Declination Vernier Drive provides the capability to make those fine adjustments. All functions of the Powerguide II and those of the optional Motorized Declination Drive Vernier Drive are controlled from the Hand Control and so this completely eliminates any possibility of introducing unwanted vibrations while using the telescope.

Right: Motorized Declination Drive installed on the Questar Duplex Fork Mount with the now obsolete Powerguide controller, on a Questar Tristand (151,558 bytes).
Click image to see enlarged view (332,338 bytes).

The Motorized Declination Vernier Drive is constructed of durable anodized aluminum with brass and stainless steel components.

Note: this Motorized Declination Vernier Drive is expressly designed for use only with the Questar 3-½ Powerguide II system, and not with the original Powerguide. Any attempt to use with any other drive controller is likely to result in damage to the motor and possibly to the controller as well.

The Motorized Declination Vernier Drive consists of several components:

  • Power and Signal Cable

  • Drive assembly

  • Support Frame with two hand knobs to install and support the Gearbox alongside the Fork Tine

Installation: To install the Motorized Declination Vernier Drive:

  • with the provided spline wrench unscrew the Declination (elevation) control hand knob retaining set screw and slip the knob off.

  • in place of the original knob slip the new knob provided with the set into place.

  • tighten the set screw to secure the replacement knob in place.

  • slip the Declination Motor assembly over the new declination control hand knob and secure the assembly into place by attaching the brace back plate to the Support Frame by means of the two provided hand knobs while holding the black metal brace on the inside of the Fork. Company Seven suggested to customers concerned about marring the paint on their fork tine to line the insides of the Frame with felt or velour.

  • finally connect the provided six pin module cable from the jack at the top of the Declination Motor into the top right jack on Powerguide II Hand Control. Note, the six pin Motorized Declination Vernier Drive cable should be plugged in only into the jack on the right side; the left side jack accommodates the cable that connects the Hand Control to the motor in the Fork Base.

Questar 3-½ Electronic Control side view 85,321 bytes Right: Questar 3-½ Electronic Declination Control. Note the natural aluminum replacement hand knob, and one of the two long bolts that span the Fork Tine and hold the Support Frame in place (85,321 bytes).
Click image to see enlarged view (202,424 bytes).

Company Seven recommends this as a fine positioning aid, it is not designed as a slewing motor to drive the telescope across large areas of the sky.

Motorized Declination Drive Specifications*
    Geared Effect (Degrees) 1 revolution of Drive = 360 degree rotation of Fork Knob
    Selectable Speeds 1.4X (35%) or 10X (1000%) Sidereal Rate. This is
    21.06 arc secs per sec. or 150.04 arc secs per second of time.
    Control Cable Connectors Modular 6 pin (RJ12)
    Extension from Fork Tine (installed) 2-¾ inches / 70 mm
    Weight (complete set) 13.6 oz. / 385 Gr.

* Specifications are subject to change.

We invite you to visit our showroom near Washington, D.C. to see a Questar first hand. Or contact us by E-mail to, or by telephone at 301-953-2000. The showroom is open Monday to Friday 11 am to 6 pm, Saturday 11 am to 5 pm. We are closed on Sundays, on U.S. Holidays, and from 25 December through 1 January inclusive.


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