K5WK:
> I am looking for something somewhere that will help
me decide between the two.
Since you're a previous Orion II owner I assume
you know all of its filters are 4-pole. As W2VJN ofInrad and Rob
Sherwood have previously written, shape
factor has *very little* impact on performance as roofing
filters beyond about -30 dB on the skirts.
The following dats is from Elecraft:
http://www.zerobeat.net/mediawiki/index.php/K3_Roofing_Filters
1. 6 dB bandwidth and 6/60 dB shape factor:
Filter BW(-6dB) Shape Factor
2700 2910* 2.9
2800 2888 1.6
*The 2.7k may have wider BW than the 2.8k. This is
Elecraft's measurement and my 2.7k closely agrees with it.
2. IMD performance:
Filter 20kHz 10kHz 5kHz 2kHz
2.7 kHz, 5 pole 100+ 98 92 n/a
2.8 kHz, 8 pole 100+ 100 93 n/a
(You'll never notice 1-2 dB of IMD performance)
Price: 2.7k included, 2.8k $125. If you order
a 2.8k in place of the standard 2.7k in your
initial order, the incremental cost is $95.
If you are seriously interested in better
filtering for SSB, I would spend my $125 for a
1.8k (or possibly even the rumored 1.5k) in
addition to the basic 2.7k, rather than using
it for a 2.8k.
73, Bill W4ZV
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