Transceiver transmitted composite noise measurements

[W3LPL]

Rob Sherwood NC0B agreed to freely share his
transmitted composite noise measurements (dBc/Hz).
Rob's measurements are limited to only those
transceivers he has access to. Bob has always
offered top measure the performance of any
transceiver, but of course he needs access for
testing.




Transmitted composite noise is only an issue
in your immediate local area -- such as
interference to other hams within several miles
if you'd like to retain their friendship --
or to co-located transceivers in your own station
for SO2R, multi-op or Field Day.


Transmitted noise can be controlled by transmitter
bandpass filters to reduce noise into transceivers
operating on other bands but a bandpass filter
can't reduce noise radiated into a transceiver
operating in the same band such as a CW and SSB
transceiver in the same band during Field Day.


Composite transmitted noise is significantly worse
for some transceivers when their output power is
reduced to drive a modern amplifier. Rob shared his
data -- see below -- for all of transceivers he
has tested for transmitted c omposite noise at
30 watts output. Transmitted noise from some
transceivers is much worse at reduced output
power than others, most notably the IC-7300.


K3S transmitted noise with 30 watts output power
is increased by 9 dB at 10 kHz from the transmitter
frequency, but noise power 100 kHz from the
transmitting frequency is degraded only 3 dB,
the minimum degradation one would ever expect.


Transmitting on 20 meters
All values in dBc/Hz
Transceivers set to 100 watts output power


offsets from suppressed carrier frequency
Transceiver 2 kHz 10 kHz 20 kHz 100 kHz


Flex 6700 -130* -143 n/a -148
K3S -141 n/a -143
FTdx-101D -133 -137 -138 -141
FTdx10 -126# -130 -131 -135
IC-7851 -129 n/a -138
IC-7610 -128 -130 -142
Flex 6400 -122 -127 -139
IC-705 ^ -120 -121 -122 -128
IC-7300 -121 -121 -124
FTdx-3000 -120 n/a -121
TS-890S -116 -119 -127 -139


* measured at 1 kHz offset
# measured at 2.5 kHz offset
^ IC-705 tested at 10 watts


Transmitting on 20 meters
All values in dBc/Hz
Transceivers set to 30 watts output power



offsets from suppressed carrier frequency
Transceiver 2 kHz 10 kHz 20 kHz 100 kHz


FTdx-101D -129 -134 -135 -137
K3S -132 n/a -140
IC-7851 -123 n/a -133
FTdx10 -120# -123 -124 -129
IC-7610 -122 -124 -127
Flex 6400 -120 -125 -137
IC-705 ^ -118 -120 -120 -126
FTdx-3000 -117 n/a -117
TS-890S -112 -115 -124 -135
IC-7300 -110 -109 -116


# measured at 2.5 kHz offset
^ IC-705 tested at 3 watts




73
Frank
W3LPL





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[ANDY DURBIN]

Some people see no problem in taking a good neighbor and turning it into a bad one.  I'm referring to the TS-590, which performs quite will in this regard, being degraded by adding a cheap TCXO.   I'm guilty of going the cheap TCXO route but I got rid of them when I saw the test data.

Mark's measurements, and a link to mine, can be found here - https://sites.google.com/site/markstcxomeasurements/

73,
Andy, k3wyc

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