[Elecraft] Transceiver transmitted composite noise measurements

[donovanf at erols.com]

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