Click image for close-up | | | Price | | 
$181.00 | | | List Price | | | $191.00 | | | Warranty | | | 1 year | |
| This 15” diameter by 0.05” thick circular dew heater pad fits between a 16” to 18” reflector’s primary mirror and its mirror cell. It is particularly effective with truss-tube type Dobsonian reflectors, whose open framework is more prone to allow the formation of dew than a closed tube design made of Sonotube or aluminum. 18” mirrors are usually kept completely free of dew, although minor amounts may form at the very edges of the mirror under severe dewing conditions. Increasing the heater temperature will usually cure the problem. The pad is made of two sheets of rubberized fabric cemented together. Imbedded between the sheets is a heater element made of a single thin strand of nichrome wire many feet long. The wire is laid in a maze-like pattern so that it warms the entire surface of the heater pad. Since the pad is in direct contact with the back of the primary mirror, the warmth of the heater element is transmitted very effectively into the mirror. The result is that you need less energy to keep your mirror dew-free. The heater pad draws 5 amps at full power (power consumption at normal operating levels will generally be 40% to 60% less, as the normal standard controller setting is medium to low). It has a permanently attached 4’ power cord terminated by a male RCA plug for connection to the heater control unit. |
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