|My single-lever PCB keyer KI6SN/NB6M-style|
K7QO, Chuck Adams, wrote "Using an Iambic Paddle" and compared the dual-lever paddle with the single-lever with respect to number of movements. If all 26 letters of the English alphabet and the numbers from 0 to 9 are sent, the single-lever paddle requires 73 strokes while a dual-lever and an iambic keyer requires 65. This is 11% less.
But when N1FN, Marshall G. Emm, wrote "Iambic Keying - Debunking the Myth" he analyzed the 7 letters that are faster to send with an iambic keyer - C, F, K, L, Y, Q, and R - and found that only one of them, the L, is among the 12 most frequent ones in English. He illustrated it this way:
So this doesn't explain the fact that many of the high speed champions do so well on single-lever paddles. My experience is based on learning to send Morse code at the age of 47. Somehow I feel that this was 20-30 years too late in order to master all the finer movements involved in iambic keying.
The issue must be tolerance to errors, not just efficiency. The high-speed champions value that and increasingly the producers of morse paddles are including single-lever paddles in their assortment.
A single-lever paddle is also easy to make yourself, much easier than a dual-lever paddle. I made one from printed circuit board based on the paddles of KI6SN. That design was a modified version of the miniature single-lever paddle of NB6M. I made it just to try the concept before I move on and eventually buy one. But the homemade one was surprisingly good to use, so I might stay with it for a while. The nice thing is that the single-lever couldn't care less if your keyer is set up for iambic A og B. Neither if the keyer does the ultimatic mode which I promoted recently (Is the ultimatic Morse keyer really that efficient?)
There should be freedom in choice of paddle, so everyone should find what suits best regardless of what is the current fashion or what it is that is considered to be 'best'. So whether you are a newcomer who struggle with learning to send properly with an iambic keyer, or an oldtimer who keep using the dual-lever as if it is a single-lever paddle, feel free to change to a single-lever paddle. I am sure you will notice a reduced error rate.
The question for me is what "real" single-lever key I should upgrade to, they all look attractive: Begali, Bencher, Bushwhacker, Hi-Mound, Kent, K8RA, N3ZN, Scheunemann, UR5CDX, Vibroplex, ...