Description AstroSystems amazing Dew Guard secondary mirror heating system automatically senses the air temperature and the mirror temperature, then maintains the secondary at a preset (adjustable) temperature above the ambient air temperature. Gently warms the secondary at 2-4 watts when on full. The DG-1 has 4, The DG-2 has 6 and the DG-3 has 8 evenly spaced contact points for optimal thermal distribution. Uses any external 9-15 volt dc supply or you can run on a 9v battery mounted at the holder, eliminating the need for wires across the spider. Note: 9V rechargeable NiCd or NiMH batteries will not work, they are only 7.2-8.4V and have low capacity, rechargeable Lithium cells are 9V and will function properly. No more heat ropes! Three sizes to choose from. DG-1 fits 1.3-2.1" Mirrors DG-2 fits 2.6-3.1" Mirrors DG-3 fits 3.5-6.0" Mirrors Note: If your secondary is glued to a center post, the Dew Guard cannot be used. If your secondary is exposed and not inside a shroud the Dewguard will not be effective in controlling dew.
