On 2021-02-13 10:51 AM, Jim Thomson wrote:
## meanwhile, the Elecraft K3 is a lousy -29 db PEP (IMD3) at
100 watts pep out. The ANAN 7000 / 8000 is a lousy -30 db pep
(IMD3 ) with pure signal disconnected. On most of these SS
xcvrs , when power output is reduced, the IMD drops like a rock.
A TS-850 is -30 db PEP when run at max rated 100 watts pep
output..... which drops a whole bunch when run at just 85 watts
pep out..... which then drops through the floor when run at 50
watts pep out.
All of this is a result of using output devices rated for saturated
power output at 12 Volts. If one looks at the spec sheets for all
of the devices used in the mentioned transceivers, *IF* the spec
sheet shows parameters for IMD, it will be significantly better at
60 to 80 W PEP than at 100 W PEP.
Amateur transceiver manufacturers *MUST* get their design heads out
of where the sun don't shine and start using 24V devices for 100W
power levels and 48V devices for 200W power levels. Driving solid
state amplifiers well past the 1 dB compression point guarantees
IMD3 worse than -30 dB and it is time to stop accepting such garbage.
73,
... Joe, W4TV
On 2021-02-13 10:51 AM, Jim Thomson wrote:
## meanwhile, the Elecraft K3 is a lousy -29 db PEP (IMD3) at 100 watts
pep out. The ANAN 7000 / 8000 is a lousy -30 db pep ( IMD3 ) with pure
signal disconnected. On most of these SS xcvrs , when power output is
reduced,
the IMD drops like a rock. A TS-850 is -30 db PEP when run at max
rated 100 watts pep output..... which drops a whole bunch when run at
just 85 watts pep out..... which then drops through the floor when run at
50 watts pep out.
I see the same thing on my FT-1000D and also my FT-1000MP-MKV.
## IMO, I see nothing wrong with referencing IMD to pep output. S
meters are all peak reading devices, whether a panel meter or peak reading
leds. If Joe ham is say 30 db over S9 on ssb mode,
but only S9, when tuned off freq by XX khz, then Joe hams IMD is down 30
db...end of story. We dont say Joe hams splatter is 24 db down from one
tone of a 2 tone signal.
Jim VE7RF
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