Re: [Orion] from a new subscriber

[Bill Tippett <btippett@alum.mit.edu>]

Hi Jerry,

K8RA wrote:

>As he transmitted, I went about 2 khz from him on another weak signal 
(~S3 or
4) and compared all my radios.   The only radio that survived was the 
Orion.  I
could still tell he was there and there were some clicks going on from him but
I could continue to hear the intended signal.  Note that I had the BW tight 
and
I do have all the optional roofing filters in the radio.  The other radios, I
heard only white noise from the synthesizers as my neighbor transmitted.
Everyone praises the K2 but it too was destroyed.  I am a true believer.  The
Orion really is a good radio and I would rather have 3 of them in a rack than
an IC-7800.

        A couple of comments on this:

1.  What you were checking was Blocking Dynamic Range (BDR).  If you had
DSP BW tight, you were probably on your 250 Hz roofing filter.  This filter
position has some problems with IMD compared to filters in the 1000 slot.
I'm not sure of the 250's performance, but it is probably similar to the
500 Hz which has been measured at about 23 dB worse IMD performance than
the Inrad 762.  You can search Inrad 352 (old kit version) or 762 for more
info, but I would suspect your results might have been even better with a
762 in the 1000 slot (I've seen no BDR comparisons but that's my guess).

2.  At 2 kHz spacings, the K2 falls apart, despite it being one of the best
at 5 kHz spacings.  You can see where the K2 falls in Sherwood Engineering's
comparative IMD measurements at 2 kHz spacings here:

http://www.sherweng.com/Dayton_2004/Dynamic_Range_Data.pdf

Also note Orion's performance at 1 kHz with the 500 and 1000 filters.  The 762
is another ~10 dB better than the 1000 Hz at 1 kHz spacing according to 
Sherwood.
More info and some background here:

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

                                                        73,  Bill W4ZV






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