[Elecraft] Re: second followup: k1 band board options

[Morrow, Michael A.]

David Toepfer wrote:

> Is there a reason why I caould not set up a 4-band module to
> run on 40m, 30m, 17m, and 15m (I have no use for 20m right now).

I'd say there would be **NO** problem doing what you seek.

The "official" position is that the only bands available on the
four-band filter board are 40, 30, and 20 meters, plus the choice
of either 17 or 15 meters.

But...the same inductances are used (T1 through T4) in the pre-mix
and RF band pass filters on all bands 40 through 17 meters.  The
only difference between the 20, 17, and 15 meter circuits is the
adjustment of the associated trimmer caps.  And, the fix-tuned low
pass filter is completely unchanged for operation on 20, 17, or 15
meters.

I suspect that you could get a KFL1-4 to work quite well on 17 and
15 meters, if you are willing to sacrifice 20m.  Just install a 17m
crystal in place of a 20m crystal for X2 on the filter board, and
align the trimmers that would normally be adjusted for 20m (C3, C4,
CC, and CD) to peak for 17m instead.   =20

> I know I may have to buy a 2-band module for the parts for the
> additional parts to accomplish this on a 4-band board.

Not at all!  The four-band filter board comes with both the 15m and
the 17m crystals needed.

> But is it just not possible for some other reason?

I think most, myself included, would have never even considered
sacrificing 20m for 17m coverage, so I've never seen this topic
raised before.  Yet, I see no technical difficulty as long as the
normally 20m trimmer caps can be adjusted to a low enough value to
resonate at 18 MHz vs. 14 MHz.  Since they have a 1 to 40 pf range,
I can't see that being a problem.

And if in the future you wished to restore 20m coverage, you would
only have to replace X2 with the 20m crystal provided with the kit,
and re-align the 20m filter circuit.

I guess Wayne could have the final say on this proposal.  May be
I'm missing something.

73,
Mike / KK5F