[Elecraft] Bandpass Filters for K2 & K3 IF for Softrock

[Jack Smith]

There's been speculation on whether an external bandpass filter between 
the Softrock receiver and a K2 or K3 is advisable to keep unwanted 
signals out of the Softrock.

I don't have a view on that other than to note that as Lyle commented, 
Larry, N8LP, has found it necessary or at least desirable to include 
such a filter with his planned LP-PAN unit.

I built a prototype Z10010-K3 bandpass filter today and posted 
performance data at 
http://www.cliftonlaboratories.com/k3_if_bandpass_filter.htm. Similar 
data on the K2 version of the filter Z10010-K2 is at 
http://www.cliftonlaboratories.com/K2_Filter.htm.

These filters are difficult to offer as a kit, as the inductors require 
careful trimming and the filter has four (interacting) trimmer caps that 
must be carefully adjusted to provide the desired shape and center 
frequency.

If there is sufficient interest, I will consider making both the K2 and 
K3 versions available in an assembled and aligned filter, with kits 
available only to those with sufficient test equipment and experience to 
successfully complete the kit.
Anyone interested in one of these bandpass filters should drop me an 
E-mail off-list. If there is sufficient interest, I'll consider a 
production run.

Jack K8ZOA