Dual Coil Deck: Single Coil & Wick
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Dual Coil Deck: Single Coil & Wick
PAGE UNDER CONSTRUCTION
Many dual coil RTAs are can be set up for either one or two coils and performance equally well when set up correctly.
However, if only one coil is required then it might be simpler to use a purpose-designed single coil RTA, as this will sidestep the most common newbie problem, which is allowing for extra cotton in the larger juice well openings on a dual coil RTA (described in detail below)
As an example, we'll install a single coil in an Arbiter 2 dual coil RTA to make it function similarly to our single-coil Destiny RTA as featured in my first RTA video, so please re-watch this before proceeding. I also assumes you've already checked and prepared your RTA as shown here
In my Destiny video, I used a single coil which was a 6 turn 26x2+36 clapton with inner Ø3mm, and could theoretically use the same on our Arbiter 2. However, since the Arbiter has a smaller inter-terminal gap, we'll use the Arbiter's four-terminal deck and install a coil with offset legs of 5.5 turns (offset coil legs depart from the circumference half a turn before a complete turn) .
WireBuddy shows a max of 6 turns, so it'll comfortably accommodate 5.5. Also, it's suggesting a max Wattage of 23 for 6 turns, and 19W for 5, so for 5.5 turns we'll be good for upto around 20-21ish Watts without risking overdriving the coil
I'd suggest Ni80 or Kanthal A1 wire, which'll eliminate any concerns about whether our mod has the Stainless Steel Firmware Bug (described here - scroll down to "Stainless Steel Firmware Bug")
For this, I wound the coil around the 3mm part of a stepped diameter coil rod (see this page for details). This, like (many other coil winding tools) produces a slightly oversized inner Ø (by ~0.2mm), but for our purposes, this can be ignored.
To cut the correct coil leg length, use a coily measuring tool (see this page for description), or micrometer (the manufacturers recommend 5mm for both Arbiter Solo & Dead Rabbit V3). However, be prepared to trim further to visually obtain the correct height. In short, ensure there's sufficient space beneath the coil for airflow, but not so high as to risk contact with the main body when assembled.
Left & centre: trimming the coil legs to the manufacturer's specs with a "coily" tool or micrometer (5mm for Arbiter 2 and Dead Rabbit V3 RTA). These aren't essential and it can be done by sight with care.
Right: coil ready for installation, 5.5 turns with offset legs. Coil shown is anticlockwise, but for the Arbiter and DR V3, it can be either in single coil mode
As we have four terminals available, we'll mount the coil as shown in the pics, roughly central along & across the deck and horizontally level.
After securing with the grub screws, perform a red heat burn & strum out any hotspots, ideally with ceramic tweezers but a small flat blade screwdriver is also be OK.
Also, (if space permits) I suggest spacing out the coil windings a little, just enough to see daylight between them, which will reduce the risk of inter-winding electrical contact during the coil threading
How it should look on the Arbiter 2. Use a similar height above-deck on the Dead Rabbit V3 RTA
Offset coil legs will simplify fitting on ths deck. Use any two terminals that cross the curly peek insulator strip
Left: Initial red-heat dry burn showing significant hotpots.
Mid: Heating evenly from inside to out following strumming and a gentle separation of the windings.
Right: Cooled with windings separated just enough to see daylight between windings. So now ready for wicking.
Dual coil decks tend to have much larger juice well openings than their single coil counterparts, as they're designed to accommodate cotton from two coils.
A common cause of flooding/leaking/gurgling is insufficient cotton in the juice well openings. Therefore, when setting up a dual deck in single coil mode, its crucial to ensure there's sufficient cotton in them.
💡There needs to be enough cotton spread evenly in the well openings to prevent reservoir juice from bypassing the cotton and entering the inner chamber. Only wick-resident juice is allowed here
The Arbiter 2 juice well openings (left) are significantly larger than the Destiny's (right) because they're designed to take cotton from two wicks, not one.
There are a few ways to address this issues, the one we'll use here is to cut the cotton slightly longer and use the extra to bulk up in the extra free juice well space.