W0YG wrote:
>So, if this doesn't wrap, you can see that Rob's test give a 93dB dynamic
range with the 1 KHz filter at a close in spacing of 2 KHz, something the
ARRL test does not explore.
Charlie, ARRL does test close spacings (to 1 kHz) but you have to
interpolate the bottom left graph on page 20 of their Expanded Test Report
instead of reading from a table. There is very close agreement (1 dB)
between Sherwood's IMD and ARRL's IMD measurements, both Preamp Off and
using the 1000 Hz roofing filter:
Spacing Sherwood ARRL
1 kHz 85 dB 84 dB
2 kHz 93 dB 92 dB
My best guess for the Inrad #352 600 Hz Kit is that it will improve
the 1 kHz measurement to about 93 dB, and probably in the range of
85 dB for signal spacings of ~500 Hz. Nobody tests spacings this close
...except for many contests. ;-))
The very close agreement between the Sherwood and ARRL measurements
give me greater confidence in both.
73, Bill W4ZV
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