On 2020-03-02 12:13 PM, Jim Brown wrote:
Turned out it was his radio, a $1700 Yaesu FTDX3000.
Yaesu, in particular, "tune" the IF gain of their rigs
too "hot". W8JI has documented the issue as far back as
the FT-1000 and FT-1000MP. The "hot" IF causes the final
amplifiers to be driven into clipping which is hell on
IMD.
When a user cranks up the low frequency audio EQ on those
rigs and then uses high level of audio processing the
unfiltered (as in after the DSP/IF filter) PA chain
clipping runs wild.
73,
... Joe, W4TV
On 2020-03-02 12:13 PM, Jim Brown wrote:
On 3/2/2020 8:34 AM, Grant Youngman wrote:
I know this is a sensitive, if not plain explosive, topic in some
circles — but most AM users do manage their bandwidth with common
sense, and to be considerate of the rest of the community.
Not related to AM, but my P3/SVGA sees a LOT of very splattery SSB
signals generated by low cost JA transceivers. A few weeks ago during a
contest, I saw it on the signal of a local, fairly new ham, told him
about it, and volunteered to help him fix it by listening and watching
as he adjusted drive to his amp. Turned out it was his radio, a $1700
Yaesu FTDX3000. Splatter from these signals is often as wide on both
sides of the signal as the signal itself. I measured his splatter as
less than 20 dB down from his intentional signal.
There's a roundtable that hangs out just above the FT8 slot on 160; most
of the radios are clean, but there's usually one or two that splatters
down into FT8.
73, Jim K9YC
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