Thanks Vic, I should take a look at the Idiom Press devices. Can't hurt to have one more keyer ;^D
On Fri, 17 Apr 2009 12:26 -0700, "Vic K2VCO" <v...@rakefet.com> wrote: > dw wrote: > > > Before rolling my own, I talked to one designer who provides updates for > > his keyer device. > > And he got all holier-than-thou on me when he understood that I wanted > > width control for all three elements. > > > > My last cw rig utilizes the Curtis weighting schema and the dits were > > too short and the dahs too long. > > So with this adjustment schema, it was just not possible to get a > > satisfactory product. > > In perfect CW, spaces and dits should be the same length. Dahs are > supposed to be 3 times > the length of a dit. > > A weight control varies the dit:sapce ratio. Since most keyers base the > length of dahs on > the dits, it also varies the dah:space ratio. > > It's not too hard to get a keyer to close a circuit with the proper > ratios. The > complexities crop up when you connect it to a transmitter. > > Some transmitters shorten all keyed elements by a fixed amount, say 3 ms. > If your keyer > produces perfect code, then you will have two problems: both the dits and > dahs will be a > bit short (insufficient weight) and the ratio between the dits and dahs > will not be 3:1, > because the shortening is a greater percentage of a dit than of a dah. > > The problem will get worse as speed increase because the shortening will > be a greater > percentage of both dits and dahs. > > If you only have a weight control, you can't fix this. If you adjust it > so that the dits > are right, the dahs will be a bit long. Say the dit was supposed to 50 ms > lon but the > transmitter shortened them to 47. Then you adjust the weight control for > 50 ms dits again. > That means the circuit is actually closed for 53 ms on a dit, and 159 ms > for a dah. When > the transmitter shortens the dahs by 3 ms., they come out 156 instead of > 150! > > You could solve this by having separate adjustments for dit:space ratio > (weight) and > dit:dah ratio. But this would only work for a single speed. > > The simplest solution is to implement keying compensation, where you can > have the keyer > add a fixed amount to each keyed element -- in this case 3 ms -- > regardless of speed. > > This is what the Idiom Press keyers do. In addition to a weight setting > there is a > compensation setting. You set the compensation to undo whatever your > transmitter does, and > then set the weight according to your personal preferences. > > -- > 73, > Vic, K2VCO > Fresno CA > http://www.qsl.net/k2vco -- bw...@fastmail.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
