Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>First, use a wire that isn't vulnerable to RF tracking.. I always use 200 degree C. double-insulated wire for all my windings and never use the single coat wire. If using a PVC pipe, sand it inside and outside prior to winding. Heat it up good with a heat lamp and then apply 2 coats to seal the tube --- interior and exterior --- prior to winding. Allow 24 hrs to dry and then wind the wire on with the sealant dry. Dolph's AC-43 is one of the best for coil work as it is especially formulated for high dielectric constant, excellent anti-tracking properties, and it holds the wires tightly together after it dries. You can rapidly apply the AC-43 to the turning coil with a small 4 inch paint roller. The paint roller will leave air bubbles, so go over it by holding a paint brush against it while it is rotating and this procedure removes all the air bubbles. The paint roller works especially good for rapid application to a large dia. coil, ie, 10 inches and above.
The varnish serves mainly to hold the wire securely in place. As the temp drops the coilform will contract slightly, and, especially in large dia. coilforms, the wire will loosen up a bit and may even overlap. I usually use four separate finish coats and allow each coat to dry a full 24 hrs.
Sealing the exterior also prevents any moisture or humidity from getting in to get behind or on the winding.
Dr. Resonance
Would someone kindly explain to me the process and purpose of varnishing the windings of the secondary? Specifically, it seems to me that when we are varnishing the coil form raw and letting that cure and then varnish again after we wind the wire then the back of the wire still remains vulnerable with just the enamel insulation of the wire. Of course this assumes close spaced winding. Or am I just not seeing the purpose of this exercise. If we were doing this for insulation purposes I would like to put a layer of varnish on the form mounted to the winding mechanism and while still wet wind the wire. What's up here?Russ, Monitoring Lightning at the Cape