Re: New K1 on the way - Band Module Questions

Posted by Mike Morrow-3 on Jul 26, 2009; 3:19am
URL: http://elecraft.85.s1.nabble.com/New-K1-on-the-way-Band-Module-Questions-tp3323422p3327754.html

Sandy wrote, and the information supplied by Elecract seems to imply, that:

>The 4 band board can be only used on 40/30/20 and 17 OR 15 meters.

This board is actually more flexible.  It can be used on 40m, 30m, and ANY two
of the 20m, 17m, and 15m bands.  The assumption that Elecraft makes
was that nobody would ever choose not to use 20m.  If that is valid, then
likely very few would choose 17m over 15m either.

>That's the way it's designed and your only option is whether the topmost band
>will be 17 or 15 meters.

The real choice is which of the 20m, 17m, and 15m bands you will select to assign
to the *two* top bands.   The common elliptical filter for 40m can be used for 30m
since the highest frequency that will be passed is less than two times the lowest
frequency.  Similarly, the other elliptical filter on the four-band board can be used for
ANY combination of 20m, 17m, and 15m, because no frequency the filter will pass will
be greater than twice the lowest frequency that it will pass, for those bands.

It makes *no* technical sense to select a two-band board for two of the five bands
that the four-band board can support.  The four-band board has much better
filtering than does the two-band board.  The two-band board is inferior in performance
on any band that is available on the four-band version.  The only advantage of the
two-band board is that it is cheaper (for good reason) than the four-band board,
if the four-band board covers the two bands in which the builder is interested.  The *only*
technical advantage of the two-band board is that it can be built for the bands that
the four-band board doesn't cover.

I built my four-band board for 40/30/20/15m, and re-built an old two-band board for
80/17m.  That covers all six "official" bands supplied by Elecraft for the K1.

The four-band board offers the happy coincidence of double the band coverage,
with better RF performance on those bands, compared to the two-band board.
Elecraft should make note of that to customers who initially choose a two-band
board for bands that the four-band version covers.

Mike / KK5F
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