Hi Guys,
I have been watching this thread with some interest, although clicky
transceivers are not a problem in this part of the world, due to the low
population density.
One thing comes to mind, though. Why does the ARRL lab judge key click
performance by observing keyed waveforms in the time domain? It is very
difficult to draw any meaningful conclusions from time domain measurements
without performing an accurate FFT (fast Fourier transform). Direct
frequency domain measurements, using a mixer and filter would surely be
easier to analyse.
In the commercial FM market both the EIA/TIA in the US, and ETSI in Europe,
insist on frequency domain measurements of what is called transmitted ACP
(adjacent channel power). Although the measurement takes a little care to
perform, it is not too difficult, and I am sure that a similar technique
with reduced measurement bandwidths and offsets, would give a much better
comparison between various rigs.
Maybe someone in the US would like to pass this on to the ARRL?
On the subject of ALC, I'm afraid I don't use ALC in my homebrew rig. I
have a PIN attenuator in the drive chain, which is controlled from a pot on
the front panel. On each new band I adjust the power from the low end of
the pot either with a whistle on SSB, or key down on CW. The problem of ALC
overshoot, with the attendant key clicks, is thus completely eliminated.
Although there is a VERY small chance that the antenna may develop a fault
during an over, I have never had this happen in over 30 years of operating.
73, Greg ZL3IX
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|