Tech2000 Cordless Dew Heater "Zap-On" Wrap On...And Leave It On.
No more messy cords, but if you still want big power... DO-IT FREE!  Now you have options!
We just got tired of using and selling all the pricey and messy dew-zapper goods. Had enough confusion. Then we got... creative.
"OMG- I never knew you guys existed!  Thank you for the parts, so low in cost too." ... Professional Film Crew on Discovery-Channel Job.
These ingenious products electronically inhibit lens fogging, and automatically detect extra power from 12V etc. connections.

*SHIPPING:  Add flat-fee shipping $8 for the USA lower-48 states. Inquire on exact shipping if your address is outside this or global by emailing a zip code or international address to  Note--shipping does not increase if more than one item or quantity is ordered--one parcel is one shipping cost no matter what is inside. This is good for groups or "buddy" orders and saves money.

DELIVERY:  Batteries are included. All straps and cords arrive at your address in 1-3 weeks to any USA addresses. Secondaries take twice that time. Postal priority mail is our usual, though some items may arrive by plain parcel or padded mailer if we find it necessary. No UPS or FEDEX as we reserve these explicitly for corporate client work.

We only need your shipping address and an email or telephone number to contact if problems, state qty & part number and add the $8 shipping please.

Paypal:  Use the "Send Money To" function . . .
                From you (the sender)
                To us (the recipient) entered exactly as our email. . .
                Enter your shipping address and ph, part#'s & qty there if you are not emailing us separately.
                They will advise us immediately and we fill the order with no further contact required from you.

Checks or M.O:  Checks to Tech2000, 4902 SR 257 S, Delaware, OH 43015, include your shipping address and phone or email with order items and quantity and $8 shipping.

CREDIT CARDS:  Tech2000 has opted not to accept credit cards after 25 years of it. The above payment methods are required.

INQUIRIES:  Inquire at if you have questions or need any other sorts of help.


Q:  How can I tell what my tube diameter is? Your product specification table only shows "OD".
A:  The "OD" is Outside Diameter. Sometimes it is a close-call for people to just guess at that because the telescope aperture is just the lens opening stated in inches or millimeters and the tube (or cell) that holds it is always larger by some amount that varies by manufacturer. To determine your "real" tube or dew-shroud OD where you would like to place a Zapper strap, do this . . .  Wrap a string, belt, or other flexible item around the intended location (you could use a garment tape measure if you have it). That is the circumference. Measure in inches that length after you lay it flat and straight, then divide it by PI (3.14159). This is the OD (Outside Diameter) of that location in inches. Note--One inch=25.4mm, and one mm=.03937" if you need to translate dimension between inches and millimeters. Our straps are longer than the maximum OD says in our chart (to allow generous Velcro overlap), but when our maximum OD says 6 inches for example, you had better not push that very far beyond! Better to get a bigger strap type since that also is calculated by our electronincs internally and will deliver more power for that "fatter" telescope size you have.  -Dave

Q:  When I leave the heater strap units on the tube, like you said for extra-easy-portability, won't the battery snaps wear out when I connect and disconnect each time I go out?
A:  No. These are MOLDED battery snaps very unlike the ones you are used to.  Used in High-Reliability systems that we have produced over 20 years.  They will take any punishment you might offer - and keep on clicking.  Those snaps are made that way for such roughness, commonly used by industry and military for the same reasons.  It's the 'good-stuff'. Just leave one of the snap posts connected on the battery, and simply swivel the other post to touch the remaining contact--that makes it real easy to turn on and off without actually ever un-snapping the battey.  -Dave

Q:  I have a 10" SCT.  Will the Large unit 6-10" work on that?
A:  THE SCOPE SIZE IS NOT THE TUBE SIZE!  The tube is always a bit larger in diameter than your optic aperture.  The large unit ZAP-LG straps around a maximum of 10" diameter tube.  But you have a 10" aperture optic so the tube it rests in will be larger by at least 1/2".  Especially on an SCT telescope, you should also use a DewShield blinder (cowling) device, since SCT's are not provided with a projecting cowling to protect the corrector plate from the sky radiant-sink (in the dynamical thermal sense of black-body absorber).  Read the FAQ above about OD to check actual diameter at your intended dew-strap mounting location.  -Dave

Q:  OK I know this is kind of technical, but what is this thing actually doing?
A:  The purpose is to introduce a limited and controllable caloric input into the direct circumfrential region of any optic lens, in a thermally conductive + radiative combination (transference), so as to keep the surface temperature of the outer-face of that lens just a fraction-of-a-degree above the air temperature that is at the molecular surface of that lense, simply to prevent the attachment-bonding which will ensue and produce fogging, the same way that rain (and dew) droplets happen in the atmosphere (called condensate), but there are dynamics involved also in electrostatics and black-body emission and absorbtion...  "Why is my table soaking-wet tonight but my telescope has no problem yet".  It's like intoducing BTU's but that is all about how long it takes to completely melt a ton of ice so is not the proper measurement scale in thermodynamics to be applied here--we use calories for thermometric measurement and evaluations.  Many methods of doing this for astronomical purposes have been applied from professional to mainstream advanced-amateur uses.  ALL have been costly.  Until now.  -Dave

Q:  How many Watts do these give?
A:  The question is not as relevant as you might think--like asking "how many gallons of gas will my car consume in the next 30 days". Each Zap-On unit knows what to do. It routs the Watts needed according to the unit surface and battery state from .5 to 5.29 Watts in this product line. These automatically do "electronic-gear-shifting" to boost power when more voltage is detected, or cut consumption when battery weakness is detected in order to extend the usefulness of available energy. Very smart stuff. This is a complicated and dynamical system so we do not require the user to do computational gymnastics...  for example, how many Watts do you need in Ohio, and how many in Antartica?  What season is it?  What time of night?  What is the dew-point?  What is the condensate coalescence of your glass?  What coatings exist on the top-layer and what are their coalescence factors?  How old is the coating?  Do you have additional blanketing material or shrouding? Is there any wind? Hence we only can truly limit the answer to the above and let the Zap-On device figure out the rest.
  Note-  These devices can be a bit dangerous, viral-like, alien. During use these Zap-On's will convert everything you allow them access to and there is the unusual feature, quite unusual, they are able to suck-out every Joul of energy in a battery if you allow them the time to do so - they are like The Terminator in the movie - they ABSOLUTELY WILL NOT STOP until the power supply goes to ZERO.  And I do mean really really zero.  Be aware of this and do not leave it connected to a vehicle battery system very long if you use the 12V cord connection, lest you be stranded.  -Dave

Q:  Can this be used on composite-tube telescopes?
A:  Yes.  Actually that is an advantage since the lens cell you are heating is thermally de-coupled from the tube.  Composits like carbon-fiber and fiberglass or even cardboard, have a much lower thermal conductivity than metal tubes so they will allow more heat to conduct into the lens. Butt the Zap-On strap against the lens cell rear, or directly around it.  -Dave

Q:  Does the secondary heater unit require spider conductivity or insulating?
A:  No. The cables are insulated very-fine-scale wire "zipcord", and are pre-connected. On a Newtonian secondary mirror, the user has a choice of attaching a 9V battery directly in front of the Secondary Mirror Holder (stowing the excess wire inside the holder), or glue-tacking our cable under the Spider edge (also making it invisible to the optics) to use then either a 9V battery or the 12V cords we make for newtworking more power without any separate 9V batteries being used.


12-Volt adapter cord:  Connects to any Zap-On 9V Battery snap.  Boosts power by 230% for the more serious dew-kill, and uses your rechargeable auto/marine  batteries or 12V hobby cells (min 7 Amp-Hour battery capacity recommended - this is serious dew-zap wattage).  8-foot cord standard with fused cigarette-lighter plug (custom available add $10 + $0.25/ft above the 8ft length) . You generally would only use this on larger telescopes for the front lens or on outings where you might experience all-night'er dew-point issues. Possible to cut off the cig-ltr-plug and use battery clips also, or just ask us to do it if that's what you want anyway.  We have rigged-up many different splices and other special connections for people as well--for free--just because we like you--and we ARE you! These units include a separate cigarette-lighter Y-splitter cord so you don't worry about using up your socket.