Here is full description (from message #27395) of what is happening :?
"When the radio goes into TX, that cap has to charge up via R127 -- which takes a LONG time. ?During that time, Q12 is also powering up and C122 has been sitting at zero volts, so it starts charging as well. ?This is the response of the Microphone Amplifier to the rising edge of the TX signal -- and the net result is that the Balanced Mixer (T4/D15/D16) is knocked out of balance until the amplifier stabilizes. ?The result of that is a spurious RF transmission that looks like the one I have attached as a file. ?The RF rises almost immediately to about 5-8 watts, within 5 ms drops down to about 3 watts, builds back up to 5-8 watts in another 5 ms, then slowly decays over a period of 60 ms decays down to close to zero. ?(All of this observed with the PTT line held)."
The thread starts with message #27393.
Cheers
Michael VE3WMB?
