On 10/8/2020 10:43 PM, JR wrote:
K9YC published a paper purporting to document and quantify transmitter
noise figures - which belies the claim and ultimately validates what the
ARRL Lab told me - namely neither rig is a problem.
ARRL Lab engineers are not active in contesting, hence are unlikely to
see these problems. My "paper" you referenced is a re-plotting of ARRL
Lab data for all rigs on the same scale, and at scales large enough to
clearly see differences. It is THEIR DATA, not mine.
Not a problem? Yaesu rigs used to be pretty clean on SSB; current
vintage Yaesu rigs are VERY dirty on SSB, occupying three times the
bandwidth of a clean SSB signal. W4TV, a retired broadcast engineer,
traced the cause down to their method of doing ALC. I became aware of
this when trying to work next to one of these dirty stations on the
band; the P3SVGA display clearly showed the IMD-caused splatter on both
sides of the station's intended signal. The splatter extended more than
2 kHz below his USB suppressed carrier frequency, and almost than 5 kHz
above it. A clean SSB signal (not ESSB) signal is about 2.7 kHz wide.
After this first experience, I observed a lot of signals like this, and
asked some of them what rig they were using. It was nearly always a
Yaesu. Those that were not were splattering because they were
overdriving their amp.
This is NOT parochialism, it's solid engineering, which is my expertise.
What's yours?
73, Jim K9YC
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