ASToptics 20 cm Heater Band for 50 mm Finders

ASToptics 20 cm Heater Band for 50 mm Finders

This 20 cm ASToptics dew-heater band provides gentle warmth around an optical accessory or telescope tube to help prevent condensation during observing and imaging. The manufacturer’s 12 V technical table specifies a maximum tube outside diameter of 6.5 cm for this size.

Heating and electrical connection

The band uses a 12 V RCA (cinch) connection. Its published rating is 4 W, 0.33 A and 36 ohms. These values refer to this RCA model; the separate 5 V USB range has different electrical requirements.

Fitting and control

Wrap the band around the outside of the tube and secure the hook-and-loop closure. Select the size using the tube’s actual outside diameter. Telescope aperture labels in the product name are nominal guides, rather than a measurement of the external tube.

Dew prevention

The manufacturer recommends a PWM or pulsed controller to regulate heating and extend battery life. The aim is to keep the optical surface a few degrees above ambient rather than apply unnecessary heat.

ASToptics manufacturer documentation

Compatibility notes

Electrical ratings and maximum outside diameter follow the ASToptics instruction manual, revision 2025.02 Rev A, 12 V RCA table. Nominal telescope aperture labels are not outside tube diameters.