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

Joe nss at mwt.net
Thu Apr 1 19:09:50 EDT 2021


Hi Frank,
Looks like the e mail machine strips attachments.

Can you E-Mail this directly to me?

Thanks

Joe wb9sbd  nss at mwt.ne

On 4/1/2021 1:37 PM, donovanf at erols.com wrote:
>
> 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
>
>
>
>
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