>I experience the same issue and Elecraft indicated that the FSK mark/space >power fluctuations are caused by the transmit filter's passband ripple and >where the transmit signal falls within the filter's passband. I'm using the >standard 5 pole 2.7khz filter. They indicated the 8 pole filter should be >flatter.
I'm using a 2.8kHz 8-pole as the main transmit filter and at nominal 100W output I can see a perceptible "wobble" on the wattmeter as the signal shifts between mark and space. It's hard to believe the ripples in the filter would be so steep that a 170 Hz difference in frequency of the two tones would make much difference. If you use the standard 2125 Hz / 2295 Hz mark/space convention, this would make the signal appear fairly close to the filter's transition band, assuming there's no center frequency offset applied in the transmit path. This amplitude mismatch will introduce an unintentional AM at the baud rate, but it's probably not enough to appreciably broaden the transmitted signal. I don't have access to a spectrum analyzer or I would examine this further. Maybe someone with a well-instrumented bench can have a look and report back. 73... Randy, W8FN ______________________________________________________________ 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
