Hi Joe and all,
Strong interference from loud JT65 signal pushed me to check audio transmission.
With my sound card I have found two issues with the TX signal:
major one: tone transmission is started and stopped at sinus phase different
from 0 degrees (amplitude different from value 0).
minor one: there is short tone burst before the message transmission.
Both issues exist for whole message/interval transmission and for enable/halt
sequence in part of the interval transmission.
The major issue causes clicks and wide spectrum that occupies whole transmitter
bandwidth (or SSB bandwidth for classic transceiver), making interference to
receiving stations in the JT65/JT9 band.
I have put audio files and pictures showing the issues there:
https://cloud.mail.ru/public/E7XG/pwmYLStWC
Files were recorded and analyzed with Audacity software via VBcable driver.
There is some probability I have got bad sound card/driver, it would be great
to re-check it on your computer.
73 Igor UA3DJY
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