Dew Heater Temperature?

[BlueAstra]

I have a new Astrozap 8" dew heater band and controller. The other night I tried it out, but was surprised I couldn't feel any heat on the outside of the band, and the OTA felt cool. I removed the band and pressed it against my hand. You could feel the fairly low warmth resistors (?) inside, but it wasn't too hot. The controller was on full, and it had been on the scope for an hour or so.

I'm not sure what to expect, but how hot should the dew band get? Do they have a thermistor sensing ambient temperature?

[SteveL]

Thats about what you would expect.... they are there to keep the corrector/objective (and the air just in front of it) a few degrees warmer than the ambient air temperature. Do not expect them to be warm enough to use as a scarf, or to warm your hands

The dew bands have no thermistors in them, they are only available in the more expensive dew controllers.

[BlueAstra]

Drat, I was going to use the spare output for heated gloves.

[SteveL]

I wanted one wrapped round my head under my woooly hat....

[brianb]

The other night I tried it out, but was surprised I couldn't feel any heat on the outside of the band, and the OTA felt cool.

That's right: if the OTA is warmed to any noticeable extent, you will have awful seeing. When the setting is right, you will see dew on the outside of the tube except for a band a few inches wide centred about the heater tape.