[INRAD] TT ORION II

[Bill Tippett]

K7EG:

 >I recently acquired an Orion II with TT optional roofing filters installed:
2.4, 1.8, 500, & 250.  Can anyone describe what selectivity enhancements I
might expect changing out to Inrad filters:  i.e. 752, 762, 761?  I note
there is no Inrad 250 filter for Orion.

         Are you sure you don't mean Orion and
not Orion II?  There are currently no Inrad
filters that will work in Orion II.  It uses
a unique mechanical configuration (different
than for existing Inrad Orion/Omni filters).

         George W2VJN will tell you that shape
factor is non-critical for roofing filters
beyond about -30 dB down on the skirts, and
thus there is little advantage to sharper
filters than the 4-poles used in Ten-Tec's
Orion II filters.  The purpose of roofing
filters is IMD reduction, and not ultimate
rejection which is determined in the DSP
stage.  DSP filters are sharp for moderate
BWs, but the narrowest CW filters are
intentionally widened to minimize ringing.

         None of the following work in Orion II:

http://www.qth.com/inrad/tentec_menu.htm
http://www.qsl.net/tentec/ttfilter.htm

Ten-Tec offers the new 2000, 2001 and 2002
as options specifically for Orion II *only*.

"All-new suite of ORION II-specific roofing filters is arranged in 
one, single bank to allow user to select the absolute ideal roofing 
filter for mode, band conditions, and personal preference. The narrow 
(600 and 300 Hz) filters are now located in the same initial bank 
with all the rest. This new arrangement yields subtle improvement in 
dynamic range and the new filters have less passband ripple than any 
we've ever offered. ORION II comes standard with 20, 6, 2.4, and 1 
kHz installed. Optional filters are 1.8 kHz (model 2000), 600 Hz 
(model 2001), 300 Hz (model 2002). That's not all - the optional 
filters cost less than before! "

http://radio.tentec.com/Amateur/Transceivers/TT565

                                 73,  Bill  W4ZV

P.S.  I suspect Inrad will eventually offer
equivalents to the 2000/1/2 eventually.