The roller inductor is the beating heart of any fine grained antenna tuner. The Blue Ridge Amateur Radio roller inductor is an air-core based inductor that has a value range of 1.8uh to 20uh with a Q (quality factor) of 800+. Each inductor core is constructed using plexiglas endplates and internal webbing. Each end of the inductor rides on ball bearings for smooth operation. The RF contactor that connects the front RF connector to the spinning core is our own design. We utilize nickel-silver contact elements for both spring tension and superior electrical connectivity. The coil wire is pure copper, electro-plated with tin in order to eliminate copper oxidation, and to provide excellent solderability.
Belt drive tandem roller inductors.
Our symmetric antenna tuner uses a parallel pi-network for performance and minimum power loss. This is the best possible arrangement for both efficiency and performance. It's also the most expensive to produce, due to the need to have 2 roller inductors within the same tuner.
Mounted Roller Inductors
Our rollers are mounted on a fixture in order to reduce the amount of mounting hardware (bolt holes) that go through the mid-plate, and to help keep our rollers perfectly aligned, synchronized.
Roller inductor cores are made from 1/2 inch plexiglass plates (front and rear) and 1/4 inch plexiglass webbing. The webbing is slotted in order to add strength to the structure. Each web is indexed with a number of .025 inch slots, on the edges. These edges are used to form the coil and maintain the correct distance between each turn. The coil itself is made from pure copper wire, electro-plated with shiny tin to eliminate copper oxide formation and to promote solderability. The coil ends are soldered to a nickel-silver strap that is directly connected to the phosphor bronze contactor wheel. The aluminum disk visible in the pictures above is pressed onto the center axle and is used to hold the contactor to the plexiglass endplates.
Compare our roller inductor construction to other products that are available today and we think you will see that the Blue Ridge Amateur Radio roller inductor has the best construction and the best ability to handle QRO voltages.
Inductance: 1.7 - 20 uH
Power: Full legal limit
Q factor: 800