> Surely, for purity and on SSB, a Yaesu FT-1000MP Mk-V with
> th PA set
> to class 'A' would not insult too much?! Is the Rockwell
> even better?
Most amateur transceivers are in the -30dB PEP range for low
odd-order IM products. Even without ALC operation they
aren't very good. With ALC they can be worse, but the
duration of ALC "spits" is very short and so I disagree that
the ALC problems are as harmful overall as made out to be.
In order to cause bothersome QRM, the unwanted or spurious
signal has to take out a portion of the desired signal in a
combination of time and level and the time duration of an
ALC spit is generally very short compared to the time of the
desired info on voice. Unless it is very strong compared to
the desired signal, it will have no ill effect when from a
single source.
Most of the harmful stuff is the actual IM, so even if the
1000MP MKV suffers from slow leading edge ALC response it
would be a big improvement.
As for "phase noise" what someone else posted is true. The
noise of low level stages has been worse in the transmitters
I have measured than synthesizer noises, mostly shot noise
or diffusion noise in low level transistor stages. Most of
the broadband noise in my FT1000D comes from a single FET
that is used to control ALC. That FET is after the SSB
filters, so the full bandwidth of that noise makes it to the
antenna. The receiver is the same way, a single FET of the
same type in the last IF just beyond the filters sets the
receiver broadband noise floor.
I've looked into all of this carefully because I needed to
be able to receive noise floor signals (and I have a very
low background noise level here) while my transmitter is
running at full power.
73 Tom
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