The Kendrick standard dual channel dew heater controller is simple, easy to use, compact, and lightweight. It has four 12 VDC power outputs with a total 8 amp capacity. There are two separate control knobs, each knob controlling two outputs over a 0% to 100% power range. There is a tactile click indication at 50% power on both knobs. The Kendrick standard controller also has some unique features that competitive controllers don’t, as described below.
The sleek plastic case measures 3” long x 4” wide x 1.35” deep (1.75” counting the control knobs). You have your choice of using either the supplied Velcro strips or supplied magnets to attach the controller to a convenient position on your telescope or tripod. There are two LED indicators, one for each channel, to show when the power is on. There is also a power on/off switch (Unique feature number one. No other dew controller on the market has this).
The controller has a fused male cigarette lighter plug on a detachable 6' long cord (Unique feature number two. No other controller on the market has a detachable power cord). This allows connection to a car’s cigarette lighter plug or (preferably) a rechargeable 12V DC battery (to avoid accidentally draining your car battery and leaving you stuck at your dark sky site after a night of observing). The Kendrick standard controller is fused onboard. It has an auto reset (Unique feature number three.).
There are four RCA jacks on the controller into which you can plug your heater strips. With the addition of an optional RCA splitter cord or cords, 5 to 6 heaters can be attached, as long as you don’t exceed the maximum output capacity of the controller. This would allow you, for example, to use heaters for the main objective of a small scope, both ends of a finder or guide scope, an eyepiece, and a Telrad.
This Kendrick standard controller uses MOSFET (metal oxide semiconductor field effect transistor) transistors in the controller circuit board and each power output so there are no voltage drops. This gives you the best possible performance out of your heater strips. There is a low voltage cut-off control with an LED indicator light (a Kendrick standard), and there is an LED overcurrent indicator at both outputs. In addition, the Kendrick controller is reverse polarity protected.
The power output from the Kendrick controller can be varied from 0% to 100%. As the controller is a Pulse Width Modulation duty cycle switch, it controls the power going to your heaters by turning the power on and off many times each minute. When the controller is set to the 50% point, for example, the heaters draw the same amount of current whenever they are on, but they are on only 50% of the time. Low to medium is the recommended setting for most observing conditions. The controller is RFI (radio frequency interference) free, an absolute necessity if you are digital imager.
Owners of 12” and larger SCTs may need two controllers – one for the main objective heater and a second for any other heaters you wish to operate. The heater strips for the objectives of these size scopes can nearly max out the power output capacity of the controller by themselves.