Dew-Not

[Brinders]

Hello Folks,

After some evenings of prodigious dew in January I decided that I required a more effective solution to the Celestron dew shield I bought with my C9.25 on the EQ6 Pro mount last month.

As I had already spent rather more on my new system than I had envisaged, I wanted an economical cost effective solution. I was also concerned that whatever system I purchased should not make too much demand on power.

Having read and reread the Sky at Night review of dew heater controllers I decided that the Canadian Kendrick system was rather more expensive than I would have liked and all demanded more power than was desirable.

However, I came across mention and reviews of the American Dew-Not system on the Cloudy Nights forum. The manufacturers claimed a sophisticated controller was unnecessary and that their dew bands were more efficient than their rivals.

I contacted Bern at Modern Astronomy who said that the 4 channel basic controller at £24 and the 9” dew band at £33 would meet my needs. He also advised that he would be willing to substitute the 9” heater band for the 10” one if it wasn’t long enough. However, the 9” inch is just fine with my OTA.

After some thought I decided the more sophisticated Dew-Not Dual channel 4 output PWM controller was a better buy and at £59 would not break the bank.

I placed my order through Modern Astronomy's web site and within a couple of days the controller and heater band was in my possession. Top marks for Bern and Modern Astronomy, customer service is second to none.

The controller and heater band arrived in a Jiffy style padded bag. Inside the controller had been placed in a further pink bubble wrap bag and the heater band in a clear plastic re-sealable bag. There was no other superfluous packaging or even an instruction manual or information leaflet. Although as the unit is so simple to operate I don’t suppose any instructions are really required.

The Dew-Not Dual channel 4 output PWM dew controller encases the electronics in a small black plastic box. Power is via a lead extending from the side of the box and terminating in a cigarette lighter plug to connect to a 12v supply. The box is attached to your scope or mount by a pair of very sticky Velcro strips (see pics below).

A green LED on the top right of the box confirms power is being supplied to the unit. Two knobs at the base of the unit control the amount of power being transmitted to each terminal confirmed by two amber LEDs opposite each pair of terminals on the left which brighten or dim as the knobs are turned to increase or reduce power to the heater band. I have two minor criticisms here relating to ergonomics: the control knobs are not positioned opposite their respective terminals so it is not immediately obvious as to which knob controls which pair of terminals and the amber LEDs do not pulsate with each pulse cycle as one might expect but merely dim or brighten in response to the position of the control knobs as they are turned through their marked positions: lo, med and hi. However, at this price point such criticism should not detract from an otherwise excellent product.

The heater band is well made of black brushed man-made fibre on the outer (nylon or polyester?) and a red coloured smooth silk like man-made fibre on the inner where the band touches the OTA. An elasticated Velcro strap holds the heater band securely against the OTA and a cable terminating in an RCA plug projects at one end.

I cannot vouch for the manufacturer's claim that the Dew-Not system is more efficient that their rivals, but it has held the dew at bay on one particularly cold night with high dew for over 5 hours sharing the same 17Ah 12v Maplin power pack with a notoriously power hungry EQ6 Pro GOTO GEM.

A concern that has been expressed is whether or not a heater band increases in tube turbulence. I have not noticed any and in any case, the Dew-Not has enabled me to observe and image on evenings where either the dew was so heavy I would not have otherwise bothered or my session would have been cut short. Nor have I noticed any electrical interference when CCD imaging or using my DSLR.

In conclusion, the Dew-Not system is well made, very efficient and simple to use and could be even better if the ergonomic issues referred to above were addressed. However at this price point, recommended!

Brinders

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[dogfish]

Hi Brinders

Thanks for that thorough review. This is exactly the set up (bar the fact that my OTA is a C8) that I've earmarked for my next astro purchase. Your review was reassuring and has helped me make up my mind. Only question remaining is whether or not I can afford this before Kielder?

Thanks again, Martin

[jcm]

Interesting report , Brinders.

How much cable is there between the box and the heating band? I just wondered in a small obs it would be possible to park the box on something like a shelf.

erm - on second thoughts attaching it to the scope/mount is probably better.

John

[Brinders]

Hello Martin, so far as I'm concerned it's the best accessory I've bought for my new scope. More useful even than the Crayford focuser that I think I could live without and far superior to the dew shield which keeps dew at bay for a short time (perhaps 40 minutes at best). If you suffer from dew (which is particularly bad on some still nights where I live) a heated dew system is a must and the Dew-Not as good as any I'm sure and certainly cheaper than the Kendrick system. Also the advice and support you get from Bern is second to none. Wish I could say that of all astro equipment suppliers.

John, I was wondering about the length of the leads myself as I wrote the review. I'd guess the power lead is maybe 1.25 or 1.5 metres and the lead from the heater band to the controller at least 1.5 metres maybe 2, but I'll check for you next time I have my system out (no obs for me I'm afraid). I will say though that the leads are more than long enough as you might gather from the pics. Any longer and they would become a nuisance. As you say, even with a permanent observatory, I think you would be better placing the controller on the mount otherwise you could end up in a right tangle as the mount moves.

Cheers guys,

Brinders

[Tim]

Hi, great report.

I have the same OTA but on a HEQ5 PRO Mount (wish I had gone for HEQ6 now) and a similar dew system, with the name Astrozap. Got this from FLO. I am still waiting (and waiting) for a combined dew shield and heater strip that I purchased, but in the meantime Steve sent a strip.

For now I am using a home made dewshield made from craft foam. I have so far had good success with dew clearing by having the strip sort of half hanging off the tube, and every now and then putting the cap on for a few minutes. I think the warm air moving across the face lens and contained by the lid does the trick.

On the recent very cold (-6c) nights the dew strip was unable to keep the dew, no, ice out of the INSIDE of the OTA. A swift blast from the Mrs. hair dryer did the trick there.

It is a power hungry system I guess, and I cant recommend sharing the battery pack, as the light on the mount starts to flash after about 3 hours. I will be seeking a way to power the system from the mains soon.

Is there a definitive and recommended positioning for the straps?

Cheers

TJ

[Brinders]

Hi TJ,

As I said in the review, the Dew-Not was able to keep dew off the corrector plate for about 5 hours sharing the same power pack as the EQ6 Pro. However the power pack was drained by then (not even sufficient power to park the scope). I've since bought a second pack to power the Dew-Not and my security ccd cam that I use for imaging. Argos and Maplin also sell mains 12v adapters with a car accessory socket. I have the Argos one (http://www.argos.co.uk/static/Product/partNumber/0194222/Trail/searchtext%3EMAINS+ADAPTER.htm) and have used it but I'm not sure that having a mains extension lead to power it from (in my case a mains socket in the garage) is a good idea when there's a lot of dew around; water and electricity being a potentially fatal mix not to mention the possibility of breaking one's neck tripping over a cable in the dark!

I haven't had the problem you have experienced using the Maplin pack. However, if you do a lot of slewing from object to object then clearly the extra juice required by the motors will sap power rather more quickly.

I have also used my Celestron dew shield with the Dew-Not in a similar way to your home made shield with it drooping on the OTA because of the heater band. However, the Dew-Not is so effective that I now dispense with the dew shield except on those nights when a light breeze keeps the worst of the dew at bay then the dew shield (which fits properly without the heater band in the way) is usedto keep any slight dew away: I don't use the Dew-Not in those circumstances. I have never experienced dew on the inside of the corrector plate and believe me the temperature has been well below zero with frost forming.

The heater bands have to be placed as close to the corrector plate as possible so that the gentle heat permeates the plate and keeps the dew off (see my pics). As for placing the controller, there is no recommended position I am aware of. I tried the system the first night slewing the scope all over the sky to assess the best place to mount it without getting cables wrapped or tangled. Logic told me that as the cable for the hand controller and the power supply are mounted on one side of the mount then clearly placing the Dew-Not on the opposite side should work - and it does!

Brinders

[tasco]

Hi Guys saw the review, the Kendrick premier range is definetly more expensive but there are two types of heaters - "premier" and "firefly" which is 20 quid for a 9 inch heater band so that's £13 cheaper (kendrick firefly dew band prices) The Kendrick basic controller is more expensive at £70 and the digital ones are 100 quid up. as for power consumption I suppose it depends on how much you turn up the volume.