USB or RCA dew heater strip?

[GTom]

I need a dew heater for my 90/600 apo and came across several USB models on ebay. These would make life easy apparently, as no DC-RCA adapter is needed. However, an RCA may very well have a longer life!

Any suggestions?

[AstroDad74]

4 minutes ago, GTom said:

I need a dew heater for my 90/600 apo and came across several USB models on ebay. These would make life easy apparently, as no DC-RCA adapter is needed. However, an RCA may very well have a longer life!

Any suggestions?

Hi Tom 👋  I currently use a anti fog belt/Dew heater from haida purchased from Amazon it has three heat settings and is usb which retails for £23. I use this on my lens with my dslr cameras. I have left a link to the amazon page.

https://amzn.eu/d/c581Cpf

Regards Roger 

[PhilB61]

In addition to connector types you also need to consider the current draw on your USB power supply, to deliver the same heating power at 5v draws more than double the current than a 12v powered dew strap. 

[rl]

Usb sources 0.5 amps as standard = 2.5 watts. Will this be enough heat?

RCA at 12v will supply more and is 

compatible with the controller boxes.

[GTom]

All valid points, thank you all for the replies. I do not know how much power does a ~5" metal hood need to keep the front lens free of dew, but case closed going for rca.

[PhilB61]

I think my finder dew strap is rated approx 4w and the strap for my 80mm triplet approx 10w. The 4w strap will draw 0.8 amps at 5v(USB) and 0.33 amps at 12v. For the 10w strap this equates to 2 amps at 5v and 0.83 amps at 12v. This assumes the straps are running at full power, also strap sizes and power rating will differ considerably by manufacturer, I think mine are towards the lower end of power rating.

[Jim Franklin]

I use 12V dew heaters as I find them more reliable to be honest. I do have a couple of SVbony USB ones designed for telephoto lens use - can power them from powerbanks - which work well on the finder, 102mm and the ETX125 - not that I use them that often to be honest.