RCA combo unit

[old_coot88]

Originally Posted by TV Engineer

This is completely incorrect. The diameter of the idler is critical to correct rotational speed.

This is true only in the case of a compound idler, ie., two different-sized wheels affixed to a common shaft. The diameter of a non-compound (single wheel) idler does not affect rotational speed, since the rim of the wheel is only a motion-transfer agent between the driving and driven surfaces (analogous to a fan belt). The length of the belt does not affect the speed relationship between the driving and driven pulleys.