[Elecraft] SV: Getting Ready For The 2nd RX

[Bill W4ZV]

Gary Hembree wrote:
> 
> On Wed, May 28, 2008 at 11:49 AM, Bill Tippett <btippett at alum.mit.edu>
> wrote:
> 
> Elecraft will eventually publish some instructions regarding 5-pole
> filters for
> diversity, but my understanding is that the peak variation between 500
> Hz filters is a maximum of 50 Hz.  My guess is that they'll simply
> tell us to split the difference on the 500s and not worry about it.
> If the 200 Hz has total variation of  50 Hz, then it might require
> more careful matching (since 50/210 is a significant percentage of
> total BW), but I've not seen any variation numbers on the 200 yet.
> 
> Bill,
> The variation in filter offsets must be larger than you think.  My
> KFL3A-500 has an offset of -0.75 kHz, which is 90-100 Hz higher than the
> values cited by Orin.  The offset of my KFL3A-200 is -0.95 kHz, which
> oddly enough matches the offset of my KFL3A-2.7K, not that it matters.
> Thanks for the heads up on filter matching for diversity receiving.
> 73, Gary, N7IR
> 

The 50 Hz total variation I quoted for 500 Hz filters came directly from
Wayne N6KR so I'm sure Elecraft will look at this more carefully before
giving us some guidance.  In some cases it may be necessary to return or
exchange filters, but in others (like Orin's) that will probably be
unnecessary.

Note that it's not as critical that both RX filters be matched between
bandwidths (e.g. a 2.7k and 500) as within bandwidths (e.g. one 500 to the
other 500).  Also remember if you aren't planning to use diversity, it makes
no difference at all as long as you don't assign both RXs to the same VFO
frequency.

73,  Bill
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