On Tue, Nov 20, 2012 at 8:37 AM, Steven Catani <sjcat...@gmail.com> wrote:
> When I transmit, the signal as displayed in the panadapter shows broad > tails and what looks like lots of harmonics. It also has "blips" every sec > or so where it looks like an envelope over the entire signal shows up... > this is more apparent if average is turned off. I can reduce the harmonics > by narrowing the transmit filter but this seem kludgy to me. I have made > 30+ contacts but something feels wrong. > The "blips" every second or so are the sidebands from the frequency modulation when JT65 changes tones. Remember, every time you change amplitude, frequency, or phase, you get modulation sidebands. I am not sure what you mean by "tails". If you are seeing many spectral lines other than the carrier at time other than when JT65 is switching tones, you may be overdriving the TX audio section. Start by setting the TX meter in PSDR to read mic level. Make sure that the mic level (actually the audio input level) never exceeds 0dB. I normally set VAC TX gain to produce -1dB for MFSK modes like JT65, WSPR, Olivia, MFSK-16, etc. For PSK31 or other digital modes that have a significant amplitude component I use -2dB or -3dB to ensure I have headroom and won't clip the signal in the audio stages. -- Brian Lloyd, WB6RQN/J79BPL 3191 Western Dr. Cameron Park, CA 95682 br...@lloyd.com +1.767.617.1365 (Dominica) +1.916.877.5067 (USA) _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
