Topband: Receivers

[Bill Tippett]

W8JI wrote:

 >IMO, even a 2kHz test is pretty wide for normal CW
operation. When spacing moves closer in testing, rigs like
the Orion and Omni get much better than DSP-only based
radios.

         No kidding...when was the last time you heard stations
only 2 kHz apart in the CQ 160 CW?  The only data I am aware
of for 1 kHz spacings is in ARRL's Expanded Test Reports plus
a few measurements on Orion by Sherwood.  Most other rigs' IMD
is phase noise limited at 2 kHz and less (e.g. IC-7800 and K2),
but Orion's excellent close-in phase noise plus 1000 Hz roofing
filter yields decent results even at 1 kHz spacings.

IMD @ 1 kHz  84 dB (ARRL)
IMD @ 1 kHz  85 dB (Sherwood)

Orion can also be improved another ~10 dB at 1 kHz spacings by
using Inrad's #762 600 Hz roofing filter.

http://users.vnet.net/btippett/inrad_.htm

                                         73,  Bill  W4ZV