At 11:00 AM 3/9/01 -0800, George Cutsogeorge wrote:
>
>Here are some keying test results done with real radios and an HP spectrum
>analyzer. The radios were set up at full output power and were keyed at 40
>WPM. The spectrum analyzer was setup with a narrow bandwidth and very slow
>sweep time. The dB levels given were measured at an offset of 1 kHz on each
>side of the carrier. (Total bandwidth = 2 kHz.)
>
>Radio dB down at +/- 1kHz
>
>Omni VI+ -50
>1000MP -46
>IC765 -44
>Test -51
>
>The Test was done with an HP8640B signal generator keyed on and off at 40
>WPM with a rise and fall time of 5 mS.
>
>This data shows that there really are sidebands out there which will be
>heard by adjacent channel receivers. This is a fact of life. For example:
>An Omni VI+ is sending 40 WPM and is S9 +30 dB on tune. One kHz away his
>sidebands (clicks) will be down 50 dB, or about S6 to S7 on a calibrated
>meter (not a typical S meter). Since the receiver filter also has a finite
>bandwidth even with the best filters, the transmitted signal will appear to
>be even wider. This assumes there is no blocking or IMD taking place in the
>rx or excessive phase noise in either tx or rx. If there is, he will appear
>wider yet.
>
>It's interesting to me to see how little difference there is between these
>radios. Thanks for the suggestion N0AX.
It'd be interesting to know how W8JI's modified FT-1000D would fare in the
same test.
73, Pete N4ZR
Contesting is!
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