[CQ-Contest] Transceiver transmitted composite noise at reduced output power

[donovanf at erols.com]

Rob Sherwood NC0B agreed to freely share his full transmitted 
composite noise measurements (dBc/Hz). Rob's measurements are 
limited to only transceivers he has access to. He'll be pleased to 
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 
want to keep them as friends -- or to other 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 on other bands but a bandpass filter can't reduce noise 
into a transceiver on the same band such as a CW and an SSB station 
on the same band during Field Day. 


Several hams asked about degraded transmitted noise power 
when the output power is reduced to drive a modern amplifier. 
Rob shared his data -- attached to this email -- for all of transceivers 
he has tested for transmitted composite noise at 30 watts output. 
Transmitted noise output from some transceivers -- such as the IC-7300 -- 
is much worse at reduced output power, most others are degraded 
from 3 to 6 dB. 


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. 


The top of the first page is Rob's transmitted composite noise 
measurements at 100 watts output power. 



The bottom of the first page is composite noise measurements 
at 30 watts output power. 


The second page is six meter tests on the the TS-890S 


73 
Frank 
W3LPL