Should one desire to "hear" a radio fall apart, feed a modulated carrier
at some level and measure the THD+n at the audio output at near rated
audio output.
Some of the best touted radios on the market really show poor results and
we wonder why listening long hours causes fatigue.
73
Bob, K4TAX
>
>
> Op 02/04/13, Rick - DJ0IP / NJ0IP <Rick@DJ0IP.de> schreef:
>> You guys are forgetting one very important point. Radios behave
>> different
>> in the real world, on the air, than they do in the lab with just two
>> signals
>> injected.
>>
> *snip*
>
>> What we saw in that demonstration was a single carrier
>>
> *snip*
>
>>
>> What I'm trying to say is, although our lab tests use two signals and
>> we
>> take a measurement, in the real world there can be tens of signals
>> which
>> affect how the radio behaves.
>>
> *more snip*
>
> Fully agree with all above.
> I do confirm that benchmark testing is not the same as the on the air
> result.
>
> I still not understand why everyone compares ***dead carriers***.
>
> Try modulating the signal source(es) for a change and look how completely
> different some DSPs repsond.
> I could dial in some extra 8dB on the attenuator for the K2 compared to
> the IC746Pro (=756Pro) before the signal could not be read anymore.
> Something I had noticed before on two different IC756PRoIII (one with
> Inrad roofer), while detecting weak signals on 50Mhz. This story started
> on SSB with tiny garble on the 756Pro3 vs Q4 copy on the K2. So it's not
> only CW where these difference in RX performance appear. Months of
> additional testing and comparing with several rigs confirmed this. Analog
> filtering (or analog filtershapes like the ORION) is key.
>
> See my hearing results:
> http://pa5mw.blogspot.nl/2009/12/upgrade-current-vhf-station-iv-mds.html
>
> And before that :
> http://pa5mw.blogspot.nl/2009/12/upgrade-current-vhf-station-iii-mds.html
>
> Today I use an ORION and an ORION II.
> Have tried a TS590 for several months. It is a very good TRX. But nowhere
> close to the TenTecs I use.
>
> Again, anyone trying/comparing the receiver performance of any rig;
> please use modulated signal(s) for a change.
>
> 73 Mark, PA5MW
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