[Elecraft] K4 on AM

[Joe Subich, W4TV]

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