In a message dated 5/19/04 11:30:32 AM Eastern Daylight Time, ua9cdc@r66.ru
writes:
>>Very interesting presentation there. What I did not understand is why
Orion with 500hz roofing filter is worse then Orion with 1 khz roofing
at 2 kHz spaced dynamic range test? There is * on the second line of
the table but no explanation what it means. Can somebody clear it up
for me please.
73, Igor UA9CDC<<
Orion has last two filter positions of 500 and 250 Hz selectivity configured
with additional amplifier stage, aimed at compensating the loss of the
narrower filters. This is causing degradation of overload performance and
adding more
noise.
Better solution is to use original 1000Hz filter position and replace the
1000 filter with 600 Hz filter or disable the amps. W4ZV came up and collected
orders for special order of 600 Hz filter kits from INRAD. This provides
further
improvement in excellent Orion performance without degradation due to the
amps in the 500 and 250 designated positions.
It would have been better to not use amplifiers in those last positions and
if more gain needed, use the preamp.
Yuri, K3BU.us
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